Learning Objectives of Anatomy Exam II- (OCTOBER 25th) These are the learning objectives for Anatomy Exam II. Each objective will require you to go back to your chapter PowerPoints, with respective chapter section readings, class notes and any additional resources for elaboration, context, and details. For best study results, study with the goal of relating information to previous knowledge and seek true understanding, rather than “rote memorizing ”. Histology- Chapter 3 (ALL) 1. Be familiar with the major tissue types and their characteristics. THERE ARE 4 MAJOR TYPES OF TISSUES 1) Epithelial tissue 2) Connective tissue 3) Muscle tissue 4) Nervous tissue EPITHELIAL TISSUE Epithelia: sheets of cells that cover every exposed body surface and line any internal cavities and passageways. Epithelial tissue includes epithelia and glands. IMPORTANT CHARACTERISTICS OF EPITHELIAL TISSUE: Cellularity : composed almost entirely of cells bound tightly by specialized junctions. Polarity: An epithelium generally has both an exposed apical surface (apical aspect) that faces the exterior of the body or an internal space and an attached basal surface (basal aspect). Because of the differing functions of the apical, basal, and lateral surfaces, the organelles and other cytoplasmic structures within epithelial cells are distributed unevenly between the exposed and attached surfaces, a property known as polarity. Attachment: The basal surface of a typical epithelium is bound to a thin basement membrane Avascularity: Epithelia do not contain blood vessels and are therefore avascular Sheets or layers: All epithelial tissue is composed of a sheet of cells one or more layers thick. Regeneration: Stem cells located within the epithelium divide to continually replace surface epithelial cells that are damaged or lost. FUNCTIONS OF EPITHELIAL TISSUE: Protect surfaces : internal and external from abrasion, dehydration, destruction (by chemical or
biological agents) Control permeability: any substance that enters or leaves the body must cross an epithelium Provide sensation: sensory nerves innervate most epithelia. Specialized epithelial cells can detect changes in the environment and convey information about such changes to the nervous system. (NEUROEPITHELIA : specialized sensory epithelia found in special sense organs that provide our sensations of smell, taste, sight, balance, and hearing) Produce specialized secretions: through gland cells (epithelial cells that produce secretions), unicellular glands (individual gland cells scattered among other cell types in an epithelium) and glandular epithelia (most or all the epithelial cells produce secretions.) MOST OFTEN epithelial cells have MICROVILLI - increase surface area and promote absorption LESS OFTEN epithelia can also have CILIA or STEREOCILIA : microtubule structures that move together to propel substances over an epithelial surface STEREOCILIA - are very long microvilli, but unlike cilia they CANNOT MOVE. ( DON’T FORGET: ciliated epithelium lining the respiratory tract moves mucus from the lungs toward the throat. The mucus traps particles and pathogens and carries them away from the lungs.) CLASSIFICATION OF EPITHELIA: Epithelial tissue is classified by its layers and its shape 2 TYPES OF LAYERS SIMPLE- Only one layer of cells covering its basement membrane Single layer of epithelia cannot provide much protection, so simple epithelia are thin and fragile. Nuclei is approximately at the same level within each cell STRATIFIED- Two or more layers of cells Their multiple layers of cells make stratified epithelia thicker and stronger than simple epithelia. 3 TYPES OF EPITHELIAL CELL SHAPES SQUAMOUS- Cells are thin, flat, and irregular in shape, like puzzle pieces. From the surface, the cells look like fried eggs laid side by side. Squished nucleus CUBOIDAL- Look like little hexagonal boxes and appear square in typical sectional views. Each nucleus is centrally located. Centered/round nucleus COLUMNAR- also hexagonal in cross section. However, unlike cuboidal cells, their height is much greater than their width Nucleus near the base
SIMPLE SQUAMOUS EPITIHELIUM- the most delicate epithelium in the body. found in protected regions where diffusion or other forms of transport take place or where a slick, slippery surface reduces friction Lines the pleural, pericardial, and peritoneal cavities. Lines heart and blood vessels. Lines portions of the kidney tubules. Inner lining of cornea. Alveoli of lungs. (Gas exchange surfaces of the lungs) STRATIFIED SQUAMOUS EPITHELIUM- cells form a series of layers . It occurs where mechanical stresses are severe. Found on surface of the skin, lining of oral cavity, throat, esophagus, rectum, anus and vagina On surfaces where mechanical stress and dehydration are potential problems the apical layers of epithelial cells are packed with filaments of the protein keratin. May be keratinized or nonkeratinized.
Keratinized stratified squamous epithelium are tough and water resistant. (Found in hair shafts and palmar skin) Nonkeratinized , or mucosal , stratified squamous epithelium also resists abrasion but must be kept moist, or it will dry out and deteriorate. (Occur in oral cavity, pharynx, esophagus, rectum, anus, vagina) SIMPLE CUBOIDAL EPITHELIAL- provide limited protection and are found in regions where secretion or absorption takes place. Found in glands, ducts, portion of kidney tubules, thyroid gland STRATIFIED CUBOIDAL EPITHELIAL- ARE RARE Found lining the ducts of sweat glands and mammary glands SIMPLE COLUMNAR EPITHELIUM- is found in areas where absorption or secretion occurs. Columnar epithelia provide slightly more protection than simple cuboidal epithelia . Found in lining of stomach, intestine, gallbladder, uterine tubes, collecting ducts of kidneys STRATIFIED COLUMNAR EPITHELIUM- ARE RARE May have two or more layers. If it has more than two layers, only the superficial cells are columnar in shape. Found in small areas of the pharynx, epiglottis, anus, mammary glands, salivary ducts and urethra. Two specialized epithelia line the respiratory system and the hollow conducting organs of the urinary system. PSUEDOSTRATIFIED CILATED COLUMNAR EPITHELIUM - a specialized columnar epithelium that includes a mixture of cell types. Functions include protection and secretion Found in lining of nasal cavity, trachea, bronchi & in portions of male reproductive TRANSITIONAL EPITHELIUM- is a stratified epithelium that can stretch without damaging the epithelial cells. Permits expansion and recoil after stretching Found in urinary bladder, renal pelvis, and ureters Nucleus appears to be scattered
CONNECTIVE TISSUE CONNECTIVE TISSUES HAVE 3 BASIC COMPONENTS 1. Specialized cells 2. Extracellular protein fibers 3. *MATRIX*- A fluid known as ground substance ** CONNECTIVE TISSUE CONSISTS MAINLY OF EXTRACELLULAR MATRIX** MATRIX- extracellular fibers and ground substance form the matrix that surrounds the cells. FUNCTIONS OF CONNECTIVE TISSUE: - Establish a structural framework for the body - Transport fluids and dissolved materials from one region of the body to another - Protect delicate organs - Support, surround, and connecting other tissue types - Store energy , especially in the form of lipids (adipose tissue/fat) - Defend the body from invasion by microorganisms 3 MAIN CATEGORIES OF CONNECTIVE TISSUE
1.CONNECTIVE TISSUE PROPER- HAS A MATRIX OF FIBERS (LOOSE FIBERS AND DENSE FIBERS) contains extracellular fibers and a viscous (syrupy) ground substance. It has two classes of cells , fixed cells and wandering cells. FIXED CELLS- are stationary and are involved with local maintenance, repair, and energy storage . WANDERING CELLS- help defend and repair damaged tissues. CONNECTIVE TISSUE PROPER HAS 3 TYPES OF FIBERS: COLLAGEN FIBERS - The strongest and most common fibers in connective tissue proper, collagen fibers are long, straight, and unbranched . - Collagen fiber is flexible but very strong when pulled from either end . - Tendons and ligaments consist almost entirely of collagen fibers ; alignment of collagen fibers in tendons and ligaments allows them to withstand tremendous forces. RETICULAR FIBERS- Provide a supporting framework. - Reticular fibers are thinner than collagen fibers , and they form a branching, interwoven framework that is tough but flexible . - Reticular fibers resist forces applied from many different directions and stabilize the organ’s cells, blood vessels, and nerves despite the pull of gravity.
- Found in organs such as the spleen and liver, kidney, lymph nodes, bone marrow. ELASTIC FIBERS- Contain the protein ‘Elastin’ ; are branching and wavy. - After stretching up to 150 percent of their resting length, they recoil to their original dimensions. GROUND SUBSTANSE OF CONNECTIVE TISSUE -Surrounds the cellular and fibrous components of connective tissue proper. -Is clear, colorless, and similar in consistency to maple syrup. -It contains hyaluronan and a mixture of other proteoglycans and glycoproteins that interact to determine its consistency. LOOSE CONNECTIVE TISSUES - “packing material” of the body - fill spaces between organs, provide cushioning, and support epithelia - surround and support blood vessels and nerves - store lipids - provide a route for the diffusion of materials THERE IS 3 TYPES OF LOOSE CONNECTIVE TISSUE:
AREOLAR, ADIPOSE & RETICULAR TISSUE AREOLAR TISSUE- least specialized connective tissue in the adult body. -Connects skin to muscle - ground substance cushions shocks, and because the fibers within the ground substance are loosely organized, areolar tissue can be distorted(stretched) without damage - tissue returns to its original shape after external pressure is relieved - a layer of areolar tissue separates the skin from deeper structures - Provides MINIMAL support but permits independent movement. -Tissue has an extensive circulatory supply, so drugs injected into areolar tissue are quickly absorbed into the bloodstream. -HIGHLY VASCULARIZED ADIPOSE TISSUE - Loose connective tissue dominated by adipocytes. - most of the tissue volume consists of adipocytes FUNCTION: CUSHION AND INSULATION AND ENERGY STORAGE THERE ARE 2 TYPES OF ADIPOSE TISSUE: WHITE & BROWN FAT WHITE FAT - more common in adults , has a pale, yellow-white color. It contains a single large lipid droplet and is therefore called unilocular adipose cells. White adipose tissue cushions shocks, insulates the body to slow heat loss through the skin, and serves as padding or filler around structures . Found under the skin of the groin, sides, buttocks, and breasts . It also surrounds the kidneys and fills the bony sockets behind the eyes and areas of loose connective tissue in the pericardial and abdominal cavities. BROWN FAT - more abundant in infants and children than in adults. Fat is stored in numerous cytoplasmic vacuoles in brown adipose cells (multilocular adipose cells). This tissue is highly vascularized , and the individual cells contain numerous mitochondria, giving the tissue a deep, rich color. Found between the shoulder blades, around the neck, and possibly elsewhere in the upper body of newborn children , is biochemically active and is important in temperature regulation of newborns and young children . At birth, an infant’s temperature -regulating mechanisms are not fully functional, and brown fat provides a mechanism for raising body temperature rapidly. With increasing age and size, body temperature becomes more stable, so the importance of brown fat declines. RETICULAR TISSUE - Connective tissue consisting of reticular fibers, macrophages, fibroblasts, and fibrocytes. Forms the supporting connective tissue of the liver, spleen, lymph nodes, and bone marrow. PROVIDE SUPPORTING FRAMEWORK . DENSE CONNECTIVE TISSUE Consists of fibers. Also called collagenous tissues because collagen fibers are the dominant fiber
type. There are 2 types of dense connective tissues: dense regular and dense irregular. DENSE REGULAR CONNECTIVE TISSUE - the collagen fibers are packed tightly and aligned parallel to applied forces. EX: found in tendons, aponeuroses, elastic tissue, and ligaments. FUNCTION : Provides firm attachment -conducts pull of muscles -reduces friction between muscles - stabilizes relative positions of bones (stabilizes the vertebrae) DENSE IRREGULAR CONNECTIVE TISSUE - fibers form an interwoven meshwork and do not show any consistent pattern Found in nerve and muscle sheath FUNCTION : Provides strength to resist forces applied from many directions -Helps prevent overexpansion of organs such as the bladder.
2.FLUID CONNECTIVE TISSUE Two types of fluid connective tissue: blood and lymph , consist of cells within a liquid matrix. BLOOD - contains red blood cells, white blood cells, and platelets RBC (erythrocytes)- transport O2 and CO2 in the blood WBC (leukocytes)- include neutrophils, eosinophils, basophils, lymphocytes, and monocytes. FIGHT INFECTION PLATELETS (thrombocytes)- tiny membrane-enclosed packets of cytoplasm, contain enzymes and special proteins. Platelets function in the clotting response that seals breaks in blood vessel walls. LOCATED: CIRCULATORY SYSTEM LYMPH - Fluid contents of lymphatic vessels, similar in composition to interstitial fluid. FUNCTION : INVOLVED W THE IMMUNE SYSTEM FOUND IN : LYMPHATIC SYSTEM 3.SUPPORTING CONNECTIVE TISSUE Cartilage and bone are supporting connective tissues that provide a strong framework to support the rest of the body . Matrix contains numerous fibers and, in some cases, deposits of insoluble calcium salts. CARTILAGE- The matrix of cartilage is a firm gel made of chondroitin sulfates. -Cartilage cells (chondrocytes) , are the only cells within the cartilage matrix -Chondrocytes live in small chambers known as lacunae - Collagen fibers provide cartilage with its tensile strength, and extracellular fibers and ground substance give cartilage its flexibility and resilience - Cartilage is avascular - Perichondrium (outer covering) usually separates cartilage from the surrounding tissues & contains two distinct layers: an outer fibrous layer of dense irregular connective tissue and an inner cellular layer. Fibrous(outer) layer provides mechanical support and protection and attaches the cartilage to other structures . Cellular (inner) layer is important for the growth and maintenance of the cartilage. CARTILAGE GROWS IN 2 WAYS: APPOSITIONAL GROWTH - enlargement by the addition of cartilage or bony matrix to the outers surface (GROWTH AT THE SURFACE) INTERSTITIAL GROWTH – form of cartilage growth through the growth, mitosis, and secretion of
chondrocytes inside the matrix (GROWTH FROM WITHIN) Neither appositional nor interstitial growth occur in adult cartilage. Most cartilage cannot repair itself after a severe injury. BONE Bone is a supporting connective tissue with a hardened matrix. It has a solid matrix made of calcium phosphate Bone is made of osteons Vascular The outer covering is called periosteum Periosteum has 2 layers: outer fibrous layer, and an inner cellular layer Outer layer- helps attach bones to surrounding tissue and to tendons and ligaments Inner layer(endosteum)-functions in bone growth and in repairs after an injury 2 TYPES OF BONE: COMPACT BONE & SPONGY BONE COMPACT BONE- Dense bone containing parallel osteons. Contains blood vessels trapped within the matrix. SPONGY BONE- Bone that consists of an open network of struts and plates that resemble a 3D garden lattice. Does not contain blood vessels trapped within the matrix. MUSCLE TISSUE A tissue characterized by the presence of cells capable of powerful contractions ; includes skeletal, cardiac, and smooth muscle tissue. Produce force Contract and expand The cytoplasm of a muscle cell is called sarcoplasm Plasma membrane is called a sarcolemma SKELETAL MUSCLE TISSUE- Contractile tissue dominated by skeletal muscle fibers; characterized as striated, voluntary muscle. -muscle fibers are very long and slender
-each cell is multinucleate (containing hundreds of nuclei) -muscle fibers cannot divide but new fibers can be produced through myosatellite cells (satellite cells) - muscle tissue can partially repair itself after an injury. - Skeletal muscle fibers will not contract unless stimulated by nerves, nervous system provides voluntary control over their activities. Thus, skeletal muscle is called striated voluntary muscle . CARDIAC MUSCLE TISSUE - found only in the heart , is striated involuntary muscle. - smaller than a skeletal muscle fiber and has one centrally placed nucleus (UNINUCLEATE) - cardiac muscle cells form extensive connections with one another at specialized regions called intercalated discs (allow for FAST TRANSMISSION) - intercalated discs help channel the forces of contraction , and gap junctions within the intercalated discs help coordinate the activities of individual cardiac muscle cells - cardiac muscle cells cannot divide, and because this tissue lacks myosatellite cells , damaged cardiac muscle tissue cannot regenerate - Cardiac muscle cells do not rely on the nervous system to start a contraction - specialized cardiac muscle cells called pacemaker cells establish a regular rate of contraction. SMOOTH MUSCLE TISSUE- found in the walls of blood vessels and various organs, lining the urinary bladder, within respiratory, circulatory, digestive and reproductive tracts. Is nonstriated involuntary muscle. - smooth muscle cell is small, with tapering ends, and contains a single, centrally located oval nucleus - smooth muscle cells can divide so smooth muscle can regenerate after an injury - it is the only nonstriated muscle tissue - smooth muscle cells contract on their own, through the action of pacemaker cells, while others contract when stimulated by the nervous system
NERVOUS TISSUE Most of the nervous tissue in the body is concentrated in the brain and spinal cord. SPECIALIZED TO CONDUCT ELECTRICAL SIGNALS THROUGH THE BODY NERVOUS TISSUE CONTAINS 2 TYPES OF CELLS: NEURONS & NEUROGLIA NEURONS (NERVE CELLS)- transmit electrical impulses along their plasma membrane - longest cells in the body - neurons are incapable of dividing under normal circumstances , and they have a very limited ability to repair themselves after injury (REMEMBER IF CELL BODY IS DESTROYED, THE WHOLE CELL IS DESTROYED, BUT IF ITS ONLY THE AXON, IT MIGHT BE ABLE TO REGENERATE) - has a cell body, or soma , that contains a large, prominent nucleus - cell body is attached to several branching processes, called dendrites and a single axon - Dendrites receive incoming messages; axons conduct outgoing messages -axons are also called nerve fibers because they are very slender NEUROGLIA- supporting cells of neural tissue; these cells protect the neurons -have various functions, such as supporting nervous tissue, regulating the composition of the interstitial fluid, and providing nutrients to neurons 2. Know the various types of cells found in each type of tissues. This is all the simple , squmous, cuboidal, etc. 3. Know where in the body the different types of tissues are typically found. EPITHELIAL TISSUE SIMPLE SQUAMOUS EPITHELIA: Lines the pleural, pericardial, and peritoneal cavities. Lines heart and blood vessels. Lines portions of the kidney tubules. Inner lining of cornea. Alveoli of lungs. (Gas exchange surfaces of the lungs)
STRATIFIED SQUAMOUS EPITHELIUM: Found on surface of the skin, lining of oral cavity, throat, esophagus, rectum, anus and vagina SIMPLE CUBOIDAL EPITHELIUM: Glands, ducts, portion of kidney tubules, thyroid gland STRATIFIED CUBOIDAL EPITHELIUM: Lining of some ducts (BUT IS RARE) SIMPLE COLUMNAR EPITHELIUM: Lining of stomach, intestine, gallbladder, uterine tubes, collecting ducts of kidneys STRATIFIED COLUMNAR EPITHELIUM : Small areas of the pharynx, epiglottis, anus, mammary glands, salivary gland ducts and urethra. PSEUDOSTRATIFIED CILATED COLUMNAR EPITHELIUM: Lining of nasal cavity, trachea and bronchi, portions of male reproductive. TRANSATIONAL EPITHELIUM: Urinary bladder, renal pelvis, ureters CONNECTIVE TISSUE AREOLAR TISSUE : Deep to the dermis of the skin and covered by epithelial lining of the digestive, respiratory, and urinary tracts; between muscles; around blood vessels , nerves and joints. ADIPOSE TISSUE: Deep to the skin, especially at sides, buttocks and breasts; padding around eyes and kidneys. RETICULAR TISSUE: Liver, kidney, spleen, lymph nodes and bone marrow. DEEP REGULAR CONNECTIVE TISSUE: Between skeletal muscles and skeleton; tendons; between bones; ligaments ; covering skeletal muscles; deep fascia. ELASTIC TISSUE: Between vertebrae of the spinal column ; ligaments supporting penis; in blood vessel walls. DENSE IRREGULAR CONNECTIVE TISSUE: Capsules of visceral organs; periostea and perichondria; nerve and muscle sheaths; dermis. MUSCLE TISSUE SKELETAL MUSCLE TISSUE: Found in skeletal muscles CARDIAC MUSCLE TISSUE: Heart SMOOTH MUSCLE TISSUE: Found in the walls of blood vessels and in digestive, respiratory, urinary and reproductive organs. NERVOUS TISSUE Found in the brain and spinal cord
4. How does epithelial tissue differ from connective tissue? • Although epithelial tissue consists almost entirely of cells , connective tissue consists mostly of extracellular matrix. • Unlike epithelial tissues, c onnective tissues are never exposed to the environment outside the body. • Epithelia becomes thinner as we age, and connective tissue becomes fragile 5. What is mesenchyme? Function? What is a fibroblast? Function? MESENCHYME: The first connective tissue to appear in the developing embryo FUNCTION: This connective tissue gives rise to all other connective tissues, including fluid connective tissues, cartilage, and bone. MESENCHYME BECOMES CONNECTIVE TISSUE FIBROBLAST: One of the two most abundant fixed cells in connective tissue proper and are the only cells always present . They are slender, star-shaped cells FUNCTION: responsible for the production of all connective tissue fibers. Manufactures and secretes proteins subunits that interact to form large extracellular fibers. Secretes hyaluronan , which makes the ground substance vicious 6. Know how the three types of cartilages differ with respect to matrix, fibers, appearance and use in the body (use the text for accurate info) CARTILAGE IS A SUPPORTING CONNECTIVE TISSUE WITH A FIRM, GELATINOUS MATRIX. 3 TYPES OF CARTILAGE 1.HYALINE CARTILAGE – MOST COMMON TYPE & WEAKEST. “GLASS - LIKE”/GLOSSY APPEAREANCE MATRIX : matrix contains c losely packed collagen fibers LOCATION: - connections between the ribs and the sternum
- supporting cartilages along the conducting passageways of the respiratory tract - articular cartilages covering opposing bone surfaces within synovial joints, such as the shoulder -supporting larynx (voice box) -trachea and bronchi; forming part of the nasal septum FUNCTION: provides stiff but somewhat flexible support. & Reduces friction between bony surfaces 2.ELASTIC CARTILAGE: MATRIX: contains numerous elastic fibers that make it extremely flexible LOCATION: -auricle of external ear -epiglottis -auditory canal -cuneiform cartilages of larynx FUNCTION: Provides support but tolerates distortion (stretch) without damage and returns to original shape. Flexible support 3.FIBROUS CARTILAGE (ALSO CALLED FIBROCARTILAGE ) MATRIX: has little ground substance and may lack a perichondrium, and the matrix is dominated by collagen fibers LOCATION: *IN AREAS OF HIGH STRESS * -pads within the knee joint -between pubic bones of pelvis -intervertebral discs FUNCTION: Resists compression ; absorbs shock ; prevents damaging bone-to-bone contact; limits relative movement
7. What are exocrine glands? Exocrine glands : glands that release their secretions onto an epithelial surface through epithelial ducts. 3 TYPES OF EXOCRINE GLANDS: 1. Serous glands: Secrete a watery solution rich in enzymes , such as the salivary amylase in saliva 2. Mucous glands: secrete glycoproteins called mucins that absorb water to form a slippery mucus , such as the mucus in saliva. 3. Mixed endocrine glands: contain more than one type of gland cell and may produce both serous and mucous secretions 8. What are endocrine glands? Endocrine glands: ductless glands that release their secretions by exocytosis directly into the interstitial fluid surrounding the cell that diffuses into the blood. Release hormones . ( Hormones: regulate or coordinate activities of other tissues, organs, and organ systems.) REMEMBER: EXOCRINE GLANDS HAVE DUCTS & ENDOCRINE GLANDS DO NOT! 9. From which type of tissue are the Exo and endo glands derived? Exocrine and endocrine glands are derived from epithelial tissues 10. Be familiar with the types of endocrine glands and the various methods by which they organized. 11. What are the methods of glandular secretion? A GLANDULAR EPITHELIAL CELL MAY USE ONE OF THREE METHODS TO RELEASE ITS SECRETIONS 1. Eccrine secretion (Merocrine) : sensory product is packaged into secretory vesicles , released through exocytosis onto the surface of the cell. CELL REMAINS INTACT -Most common mode of secretion -Found in salivary glands
2. Apocrine secretion: secretory product is released during the shedding of the apical portion of the cell’s cytoplasm, which has become packed with secretory vesicles. gland cells then undergo regrowth and produce additional secretory vesicles. PART OF THE CELL PINCHES OFF -Found in mammary glands 3. Holocrine secretion: destroys the gland cell . During holocrine secretion the entire cell becomes packed with secretory products and then bursts apart. Secretion is released and the cell dies. Further secretion depends on gland cells being replaced by stem cells found deeper within the epithelium. WHOLE CELL DIES/BURSTS -Found in sebaceous glands 12. What are the characteristics of the four types of membranes? Where are they found and what do they produce? Be able to describe each of them. (Ex. Synovial, Cutaneous, Serous, Mucous) 1.MUCOUS MEMBRANE (MUCOSA)- Mucous membranes are moist and line passageways that open to the exterior of the body. Form a barrier that resists the entry of pathogens. Found in- digestive/respiratory tracts, oral cavity, and portions of the urinary and reproductive tract. 2. SEROUS MEMBRANE- Serous membranes line body cavities that lack openings to the exterior ; they minimize friction between opposing surfaces. Consists of mesothelium. There are 3 types. - Serous membranes are very thin and attach firmly to the body wall and the organs they cover THREE TYPES OF SEROUS MEMBRANES 1. PLEURA- lines the pleural cavities and covers the lungs 2. PERITONEUM- lines the peritoneal cavity and covers the surfaces of the enclosed organs 3. PERICARDIUM- lines the pericardial cavity and covers the heart. LINES THE PERITONEAL, PLUERAL AND PERICARDIAL BODY CAVITIES 3.CUTANEOUS MEMBRANE (SKIN)- covers the surface of the body. The cutaneous membrane is t hick, relatively waterproof, and usually dry . The skin is the first line of defense against environmental pathogens Found in- literally the whole-body LOL 4.SYNOVIAL MEMBRANES- Synovial membranes line and lubricate joint cavities. **SYNOVIAL MEMBRANE PRODUCES SYNOVIAL FLUID ** Although called an epithelial tissue, the synovial membrane lining a joint cavity develops within connective tissue. Synovial membrane differs from other epithelial tissues in three respects:
• It has no basement membrane. • Its cellular layer is incomplete, with gaps between adjacent cells. • Its “epithelial cells” derive from macrophages and fibroblasts of the adjacent connective tissue. 13. Be able to distinguish mesothelium and endothelium. MESOTHELIUM- simple epithelium that lines the body cavities (pleural, peritoneal, and pericardial cavities)
ENDOTHELIUM- simple epithelium that lines the heart and blood vessels 14. What is fascia? What are the different types of fasciae and where are they found? FASCIA- a layer or sheet of connective tissue that you can see on gross dissection. THREE TYPES OF FASCIAS: SUPERFICIAL FASCIA (also known as subcutaneous layer/hypodermis)- This layer of loose connective tissue separates the skin from underlying tissues and organs . It provides insulation and padding and lets the skin and underlying structures move independently . DEEP FASCIA- Consists of dense regular connective tissue. All of the connective tissue fibers in a layer run in the same direction, but the orientation of the fibers changes from one layer to another. Helps the deep fascia resist forces from many different directions. SUBSEROUS FASCIA- Layer of loose connective tissue that lies between the deep fascia and the serous membranes that line body cavities . separates the serous membranes from the deep fascia, preventing the movements of muscles and muscular organs from severely distorting the delicate lining.
SUPERFICIAL FASCIA- OUTERMOST LAYER DEEP FASCIA- MIDDLE LAYER SUBSEROUS FASCIA- INNERMOST LAYER Integumentary -Chapter 4 1 What are the layers of the epidermis? EPIDERMIS HAS 4 TYPES OF CELLS KERATINOCYTES-MOST ABUNDANT MELANOCYTES-SKIN PIGMENT MERKEL-SENSATION LANGERHANS-IMMUNE RESPONSE EPIDERMIS : The epithelium covering the surface of the skin.
The layers of the epidermis are: Stratum corneum – superficial layer Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale – deepest layer STRATUM BASALE : the deepest epidermal layer. - firmly attached to the basal lamina , which separates the epidermis from the loose connective tissue of the adjacent dermis - basal cells(large stem cells), dominate the stratum basale - Melanocytes (responsible for the production of melanin) are scattered among the basal cells of the stratum basale -Merkel cells are found among the cells of the stratum basale and are most abundant in skin where sensory perception is most acute, such as fingertips and lips. Merkel cells are sensitive to touch and, when compressed, release chemicals that stimulate sensory nerve endings, providing information about objects touching the skin. STRATUM SPINOSUM: -above the stratum basale - histologists called this stratum the “spiny layer.” -Contains bundles of proteins called tonofibrils (act as cross braces, strenghtening and supporting the cell junctions) -Melanocytes are common in this layer -Langerhans Cells are also present in this layer: cells play an important role in triggering an immune response against epidermal cancer cells and pathogens that have penetrated the superficial layers of the epidermis STRATUM GRANULOSUM: -Superficial to the stratum spinosum. - most superficial layer of the epidermis in which all the cells still possess a nucleus - consists of keratinocytes that have moved out of the stratum spinosum - manufacture large quantities of the proteins keratohyalin and keratin (tough fibrous preotein component of nails, hair, calluses) STRATUM LUCIDUM (CLEAR LAYER): -Superficial to the stratum granulosum - found in thick skin ONLY of the palms of the hands and soles of the feet - cells in this layer lack organelles and nuclei , are flattened and densely packed, and are filled with keratin filaments STRATUM CORNEUM: -the most superficial layer of both thick and thin skin - consists of numerous layers of flattened, dead cells that have a thickened plasma membrane - dehydrated cells lack organelles and a nucleus, but still contain many keratin filaments. - is water resistant, but it is not waterproof - Water from the interstitial fluids slowly penetrates the surface and evaporates into the surrounding air. Process is called insensible perspiration & accounts for a loss of roughly 500 ml (about 1 pint) of water per day.
Takes 15 – 30 days for a cell to move from the innermost layer, Stratum Basale to the most superificial layer, Stratum Corneum. 2 What type of tissue comprises epidermis? The epidermis of the skin consists of a stratified squamous epithelium. 3 What is the integumentary system proper? What are the accessory organs? Integumentary system proper is the SKIN (EPIDERMIS & DERMIS) Accessory organs are your nails, hair follicles and exocrine glands. 4 What is meant by cutaneous membrane? Cutaneous membrane is the SKIN (epidermis and the dermis) 5 Know the types of cells are found in each layer? Also know the general characteristics of each layer and how that layer is important to the epidermis Stratum corneum -dead cells Stratum lucidum -dehydrated cells Stratum granulosum -keratinocytes Stratum spinosum -keratinocytes, Langerhans, melanocytes Stratum basale -basal (stem cells), melanocytes, merkel cells REMEMBER TO REMEMBER THESE! KERATINOCYTES-MOST ABUNDANT MELANOCYTES-SKIN PIGMENT MERKEL-SENSATION LANGERHANS-IMMUNE RESPONSE 6 Know the layers of the dermis? There is 2 layers in the dermis PAPILLARY LAYER - nourishes and supports the epidermis RETICULAR LAYER – restricts spread of pathogens Stores lipids Attaches skin to deeper tissues Sensory receptors Blood vessels assist in thermoregulation
7 Know the types of connective tissues found in the dermis? Loose connective tissue found in the papillary layer of the dermis Dense irregular connective tissue is found in the reticular layer of the dermis 8 What kind of receptor cells are found in the derma[is. Tactile corpuscles - (light touch receptors) Ruffini corpuscles (stretch receptors) Lamellated corpuscles (deep pressure and vibration receptors) 9 Where do we find papillary and reticular layers? Papillary and reticular layers are found in the dermis Papillary -SUPERFICIAL DERMIS Loose connective tissue Dermal papillae Capillaries Nerve axons Reticular -DEEP DERMIS Dense irregular connective tissue Hair follicles Sweat glands Sebaceous glands 10 Know how fingerprints are formed. Dermal ridges form fingerprints, which are a unique identifier of an individual. Dermal ridges are formed in the stratum basale that extend into the dermis Dermal ridges are little folds of the outer layer of the skin
GENETIC RIDGES INTERLOCK WITH DERMAL PAPILLAE Dermal ridges: improve gripping ability and increase skin sensitivity POWERPOINT Stratum basale forms epidermal ridges Ridges extend into the dermis Creates ridges we call fingerprints 11 What is the function of the hypodermis? -*Important in stabilizing the position of the skin in relation to underlying tissues such as skeletal muscles or other organs , while still permitting movement. -Consists of loose connective tissue with adipocytes (important for kids for thermoregulation) -Subcutaneous fat also serves as an energy reserve, shock absorber. -subcutaneous layer is quite elastic -only the superficial region contains large arteries and veins, the rest is limited and has no vital organs which makes subcutaneous injection and useful method for administering drugs. 12 How do thick skin and thin skin differ? Thin skin - contains 4 layers . (DOES NOT HAVE STRATUM LUCIDUM) Most of the body is covered in thin skin Thick skin - covers the surface of the palms and soles CONTAINS ALL 5 LAYERS. Six times thicker than thin skin 13 What are the human skin pigments? Two pigments determine skin color : carotene & melanin Carotene: an orange yellow pigment Accumulates in the subcutaneous fat and in keratinocytes( especially evident in dehydrated cells of the stratum corneum) - can be converted to vitamin A which is required for epithelial maintenance and the synthesis of photoreceptor pigments in the eye. Melanin: is produced and stored in melanocytes of thin skin -amount produced is genetically determined -black, yellow-brown or brown melanin forms in intracellular vesicles called melanosomes - Little or no melanin is produced in the thick skin of the palms of the hands and soles of the feet. (that’s why these areas are usually white) - melanin pigments help protect the dermis also prevent skin damage by absorbing UV radiation in sunlight. - Melanocytes respond to UV exposure by synthesizing and transferring more melanin = skin tan -repeated if exposure will result in damage to the epidermis and dermis.
Damage to epidermis = can lead to skin cancer Damage to the dermis= premature wrinkling FYI: DERMAL BLOOD SUPPLY CAN ALSO DETERMINE SKIN COLOR. Blood contains red blood cells that carry hemoglobin. When hemoglobin binds to oxygen = RESULTS IN BRIGHT RED COLOR that is seen mostly in fair skinned people. When circulation is temporarily blocked , the skin becomes pale. “White “ During sustained reduction in oxygen, hemoglobin becomes a darker red that shows up as a bluish coloration in the skin called cyanosis . 14 Be familiar with the types of glands associated with the skin. For ex. Eccrine, Apocrine Mammary. Sebaceous glands: -OIL GLANDS -secrete sebum to lubricate the skin -Found all over the body except for the palms and soles -Released through Holocrine secretions (whole cell dies) Sweat Glands: -Apocrine Axilla , groin , nipples Produces a viscious secretion Strongly influenced by hormoes Further divides to mammary glands & ceruminous glands Mammary: produces milk Ceruminous : found only in ear canal and produces cerumen - eccrine (found in high concentrations on the palm and soles) --produce sweat for cooling purposes -thermoregulation and excretion -produce mostly thin secretions, mostly water -protection -both contain myoepithelial cells -secretions may contain pheromes (which are secretions that babies smell in order to detect and feel safe with mom) -autonomic 15 Know the accessory structures associated with skin and their components. The accessory structures of the skin include the hair follicles, sebaceous glands
, sweat glands and nails Hair FUNCTIONS: -Form in hair follicles -hairs on the head protect the scalp from UV light and bumps to the head and insulate the skull -hairs guard the entrances to our nostrils and external auditory canals help block foreign particles and insects -eyelashes perform similar functions Pathology : What are the characteristics of skin cancer? ABCD test ASSYMETRY, BORDER, COLOR, DIAMETER Be familiar with which skin cancer is the most dangerous and which is the least dangerous . • Basal cell carcinoma- least dangerous • Squamous epithelial- benign, can metastasize or become cancerous • Melanoma-most dangerous, very cancerous. Metastasizes quickly 16 What is the anatomy of a hair follicle? How does hair grow? Hairs - project beyond the surface of the skin almost everywhere except sides & soles of the feet, palms of the hands, sides of fingers & toes, lips, portions of external genitalia. a) Hair Follicles - nonliving structures that form in organs; extend deep into the dermis, projecting into underling subcutaneous layer b) Hair Papilla - peg of connective tissue containing capillaries & nerves c) Hair Bulb - consists of epithelial cells that surround the papilla d) Hair Matrix - epithelial layer involved in hair production e) Most hair has an inner medulla and outer cortex f) Medulla - contains soft & flexible soft keratin g) Cortex - matrix cells closer to the edge of the developing hair; contain hard keratin h) Hard Keratin - gives hair its stiffness i) Single layer of dead, keratinized cells at the outer surface of the hair overlap & form the CUTICLE that coats the hair j) Cuticle - layer of dead keratinized cells surrounding the shaft of hair k) Hair Root - anchors the hair into the skin l) Hair Shaft - extends from this halfway point to the skin surface, where we see the exposed hair tip m) FOLLICLE STRUCTURE : beginning at the hair cuticle & moving outward, the cells of the follicle walls are organized into the ff: i. Internal Root Sheath - produced by cells at the periphery of the hair matrix Ii. External Root Sheath - layer includes all the cell layers found in the superficial epidermis Iii. Glassy Membrane - layer is a thickened, specialized basal lamina
17 What is an erector pili muscle? Contraction of the arrector pili muscles result in goosebumps -when stimulated , the arrector pilli muscle pulls on the follicle and raises the hair . Contraction may be due to an emotional state, such as fear or rage, or to cold temperatures that produce characteristic “goose bumps”. 18 What are the 3 different types of hair that grow on a person throughout his/her life? What happens to hair as we age? Lanugo (BABY HAIR) - extremely fine and unpigmented. Most lanugo hairs shed before birth. Vellus hair (adult hair)- peach fuzz found over much of the body surface Terminal hair (adult hair)- heavy and more deeply pigmented, sometimes curly. Example: head, eyebrows, eyelashes Muscles I (Chapters 9 and 10) Chapter 9
What are the functions (give all) of muscle? Skeletal muscles have the following 5 functions: • produce skeletal movement muscle contractions pull on tendons and move the bones of the skeleton. • maintain posture and body position : skeletal muscle contraction maintains body posture. Without constant muscular contraction we could not set up rate without collapsing or sent without falling over. • Support soft tissues : the domino wall and the floor of the pelvic cavity contains layers of skeletal muscle. These muscles support the visceral organs and protect internal tissues from injury. • Regulate the entry and exit of materials- Skeletal muscles encircle the openings, orifices, of the digestive and urinary tract. These muscles provide voluntary control over swallowing, defecation, and urination. • Maintain body temperature- muscle contractions require energy and some of that energy is converted to heat. This heat released by contracting muscles helps maintain the body’s normal temperature. WHAT IS A MUSCLE FIBER? Muscle fibers make up fascicles- → >, main functional unit of a protein cell =sarcomere found in myofibrils Muscle fibers develop through the fusion of embryonic cells called myoblast . Each muscle fiber has many nuclei (MYONUCLEI) as well as mitochondria and other organelles . Fibers contain myofibrils which contain myofilaments . (thick/thin filaments) What are the three types of muscle fibers ( slow oxidative ( Red) , Intermediate glycolytic (pink) and Fast glycolytic ( white)? How are they different? Why? Be familiar with locations in the body of each type. • Dark colored (red) due to myoglobin • fatigue resistant • Aerobic metabolism • Small diameter • Run all day • Abundant myoglobin • Large number of capillaries • fatigue slowly because their mitochondria continue producing ATP throughout the contraction process • Take three times as long to contract after stimulation • Continue contracting for extended periods of time long after a fast muscle fatigues. • slow fibers contain a larger number of mitochondria than fast muscles and slow muscle fibers can break down carbohydrate’s lipids or even proteins therefore slow muscles can continue to contract for extended periods • example: leg muscles of marathon runners are determined by slow muscle fibers • example: back, calf muscles. Muscles contract continuously to maintain an upright position
• Properties between fast and slow • Low Myoglobin • high glycolytic enzyme concentration • contract using anaerobic metabolism • Example contract faster than slow fibers but slower than fast fibers • primarily carbohydrates • Fast resistant • One large diameter • Anaerobic metabolism • densely packed myofibrils • Rely on their large glycogen reserves During peak levels of activity • relatively few mitochondria • fatigue easily • produce powerful contractions • used large amount of ATP and mitochondria are unable to meet demand • as a result, their contractions are supported by anaerobic metabolism (GLYCOLOSIS) • fast fibers fatigue rapidly because their glycogen reserves are limited • can contract in 0.01 seconds or less after stimulation How are muscle fibers unique? Why do you think this is so? The characteristics of muscle fibers change with physical conditioning repeated workouts promote the enlargement of fast muscle fibers and muscular hypertrophy What do the prefixes “myo” and “sarco” mean and when do we use them? • Myo=muscle= used in anatomy (myoglobin) • Sarco =flesh = sarcolemma = plasma membrane of muscle cell- often used in biology Know what it means when we say a muscle is “excitable” Ability to respond to stimulation. • For example: skeletal muscles respond to stimulation by the nervous system and some smooth muscles respond to circulating hormones. • Produces forth and cause motion. Contractibility-shorten and exert a pull or tension- ” CONTRACTION Extensibility-the ability to continue to contract over a range of resting lengths . Elasticity-the ability to rebound towards its original length
A muscle cell and a nerve cell differ greatly. How are they alike? Differences: muscle cells are responsible for contraction and relaxation • And nerve cells are responsible for the coordination of the functions of the body through the transmission of nerve impulses. Similarities: • there two types of specialized cells • They both form tissues • Both contain mitochondria and ER. • Work together to coordinate functions of the body • They are both excitable What is the structure of skeletal muscle? Be sure you know the connective tissue membranes that surround each muscle fiber, fascicle, and muscle. EPIMYSIUM: • dense irregular connective tissue surrounding the entire skeletal muscle • separates the muscle from surrounding tissues and organs and is connected to the deep fascia PERIMYSIUM: • Divide the muscle into internal compartments. • Each compartment contains a bundle of muscle fibers called fascicle. • the perimysium contains collagen and elastic fibers and numerous blood vessels and nerve supply each fascicle ENDOMYSIUM: • Surrounds each skeletal muscle fiber • binds each muscle fiber to its neighbor • supports the capillaries that supply the individual fiber • Scatter myosatellite cell lie between the endomysium and the muscle fibers are stem cells that repair damaged muscle tissue • Found in: Epimysium- surround skeletal muscle Perimysium- surrounds each fascicle Endomysium- surrounds muscle fibers within each fascicle
How are muscles named? Be able to give examples. BASED ON SHAPE, SIZE, ORIENTATION OF FIBERS, ACTION, # OF ATTACHMENTS, POINT OF ORIGIN. (the first part of the name indicates the origin and the second part of the insertion for example genioglossus originates at the chin (GENION)and inserts in the tongue (GLOSSA). =” origins” BICEPS:2 HEADS, TRICEPS:3 HEADS, QUADRICEPS 4 HEADS. ACTION: flexor extensor and adductor indicate the primary function of the muscle. For example, the extensor carpi radialis longus is a long muscle found along the radio lateral border of the forearm. When it contracts its primary function is extension at the wrist. BUCCINATOR: TRUMPETER, RISORIOUS (GRIMMACE), SARTORIOUS (LIKE A TAILOR) (allows to cross the legs) SHAPE: • RECTUS ABDOMINIS =ON THE ABDOMEN • RECTUS FEMORIS=THIGH • TRANSVERSUS AND OBLIQUE MUSCLES WHOS FIBERS RUN ACROSS OR AT AN OBLIQUE ANGLE TO THE LONGITUDINAL AXIS OF THE BODY. OTHER FEATURES:
• LONG MUSCLES=LONGUS/LONGISSIMUS • TERES MUSCLES=ARE BOTH ROUND AND LONG • SHORT MUSCLES=BREVIS • LARGE MUSCLES=MAGNUS OR MAJOR OR MAXIMUS • SMALL ONES=MINOR • EXTERNUS=SUPERFICIAL(OUTSIDE) • INTERNUS=PROFUNDES (INTERNAL) What are the muscle types based on the orientation of fiber Parallel muscles Most of the skeletal muscles are parallel muscles! • run entire length have the muscle example biceps brachii of the arm • parallel muscle with tendinous bands (rectus abdominis) • Other parallel muscles have a twisted or spiral arrangement line example: the supinator of the forearm= muscle wraps around the proximal portion of the radius allowing supination of the hand when this muscle contracts it shortens, and body increases its diameter.
convergent muscles • Spread out like a fan or broad triangle with a tendon at the tip • cover a broad area but all fibers come together had a common attachment site (tendon) • they may pull a tendon or slender band of collagen fibers known as RAPHE. • prominent pectoralis muscles of the chest have this shape. Pennate muscles • fibers are arranged like a feather • the muscle fibers sit at an angle and attached to a tendon that runs the length of the muscle • fascicles pull at an angle • produces more tension than a parallel muscle of the same size o Unipennate-when all the muscle cells are arranged on the same side of the tendon. enlarge muscle that extends the fingers, the extensor digitorum. o bipennate muscle-the muscle fibers are on both sides of the tendon example the rectus femoris thigh muscle that helps extend the knee. o Multipennate muscle-play turn down the branches within the muscle triangular deltoid that covers the superior surface of the shoulder joint it's an example. Circular muscles • guards’ entrance and exits of long internal passageways such as digestive and urinary tracts. • when the muscle contracts that diameter of the opening decreases example: orbicularis oris of the mouth. What are the functional groups of muscle by action? When a skeletal muscle contracts to produce a movement, it plays one of four roles: agonist, antagonist, synergist, or fixator. These roles can and do change as the movement changes. • Agonist or prime mover : it's a muscle whose contraction it's mostly responsible for producing a particular movement such as flexion at the elbow. • Antagonist: it's a muscle whose action opposes that of The Agonist. PREVENTS OVERSHOOT, creates resistance o Example: if The Agonist produces flexion the antagonist produces extension. o example #2: when an agonist contracts to produce a particular movement the antagonist stretches but usually doesn't relax completely. Instead, it's tension is adjusted to control the speed and smoothness of movement. For ex: The biceps brachii acts and agonist when it contracts, flexing the elbow. The triceps brachii on the opposite side of the humerus is the antagonist and acts to stabilize the flexion movement and to produce the opposing action extension of the elbow. • Synergist: contracts to assist the Agonist in performing that action. o Provide additional pool near the insertion or stabilize the origin o ASSIST the prime mover In performing an action
• Fixator : when agonist and antagonist contract simultaneously they're acting as fixators. Stabilizing a joint and creating an immovable base. • Example: flexors and extensors of the wrist contract simultaneously to stabilize the wrist when muscles of the hand contracted firmly grasp objects with fingers. Describe the microstructure of muscle. What is a sarcomere? Be able to describe it. The dark bands are called A bands and the light bands are called I bands the thick filaments are at the center of each sarcomere and the A band. The A band contains the M line H band and zone of overlap. The M line is the center of the A band the amp stands for middle. Emmeline connect the central portion of each filament to the neighboring thick filaments. Airlines stabilized the positions of thick filaments. The edge band is a lighter region on each side of the M line that each bank contains thick filaments but not thin filaments. The zone of overlap is a dark region where thin filaments are found between the thick filaments here three thick filaments surround each thin filament and six thin filaments around each thin filament
Sarcomere makes the muscle contract. • myofibrils are organized in repeating units. • Smallest Main Functional unit of a protein cell/muscle. • smallest units of muscle fibers • differences in size density and distribution of thin and thick filaments give the sarcomere a banded appearance • What are thick filaments? What are thin filaments? Thick filaments are organized bundles of myosin, while thin filaments are made of actin along with the two other regulatory proteins-troponin and tropomyosin. Z-lines define the boundaries of each sarcomere. THICK FILLAMENTS • Thick filament is composed of a bundle of myosin molecules. • Has a double headed structure • heads position opposite ends of the molecule • during muscle contraction the heads of the myosin filaments attached to oppositely oriented thin filaments actin and pull them past one another • When the myosin heads interact with thin filaments during the contraction they're known as cross bridges ❖ When the sarcomere stretches the titin strands maintained in normal alignment of the thick and thin filaments. ❖ When the tension is removed the titin fibrous help return the sarcomere to its thermal resting length THIN FILLAMENTS • Single thin filament contains 4 proteins: • f-actin(microfilament) -composed of G-actin (subunit of actin molecule)- active site • nebulin -holds the F actin strand together • tropomyosin -my form a long chain that covers the active sites on the actin preventing actin myosin interaction. -covers binding site when muscles are relaxed • troponin- holds the tropomyosin strand in place, calcium binds to troponin , troponin drops. Tropomyosin drops, opens myosin goes in, pulls, and contracts. • Z-line- z disc makes up a sarcomere=connection point ❖ Acetylcholine- only transmitter released into synapse in the muscle ❖ released from Axon terminal to the muscle sarcolemma ❖ stimulates action potential to release calcium ions and bind to troponin
What is a motor unit? >>>fibers that innervate → >> muscle contraction • A motor unit is a single motor neuron and all the muscle fibers it controls. • The smaller the size of the motor unit the finer the control of movement will be More precise and muscular contractions. • Some motor neurons control a single fiber but most control hundreds is skeletal muscle contracts when its motor units are stimulated. What is the motor end plate? “END PLATE POTENTIAL” =axon terminal The motor end plate is a specialist area where the action of a motor neuron establishes synaptic contact with the skeletal fiber. Releasing acetylcholine, causing depolarization. Calcium rushes In. Where are calcium ions stored in muscle cells? What role do calcium ions play in muscle contraction? Sarcoplasmic reticulum-storage and release site of calcium ions in place an essential role in controlling individual myofibril contraction What is the sliding-filament theory with respect to muscle contraction? How can we observe this by looking at a slide of the sarcomere? Explains the physical changes occurring between thick and thick filaments during contraction.
❖ H bond and I bond gets smaller ❖ the zone of overlap gets larger ❖ the Z lines move closer together ❖ however with of A band remains constant throughout the contraction What is a cross bridge? What is the role of ATP? Acetylcholine? What are the T-tubules associated with the SR? Function? ❖ Cross bridge - when myosin heads interact with thin filaments during a contraction they're known as cross bridges. ❖ Acetylcholine - only transmitter released into synapse in the muscle ❖ T -tubules- (excitation-contraction coupling) permit rapid transmission of the action potential into the cell and play an important role in regulating cellular calcium concentration. – ❖ SR function- is to store calcium ions NEURAL CONTROL OF MUSCLE FIBER CONTRACTION 1. At the neuromuscular junction ACh released by the axon terminal binds to receptors on the sarcolemma.
2. The resulting change in the membrane potential of the muscle fiber leads to the production of an action potential that spreads across its entire surface and along the T tubules. 3. The sarcoplasmic reticulum (SR) releases stored calcium ions, increasing the calcium concentration in the sarcoplasm and around the sarcomeres. 4. Calcium ions bind to troponin, producing a change in the orientation of the troponin-tropomyosin complex that exposes active sites on the thin (actin) filaments. Myosin cross-bridges form when myosin heads bind to active sites. 5. Repeated cycles of cross-bridge binding, pivoting, and detachment occur, powered by the hydrolysis of ATP. These events produce filament sliding, and the muscle fiber shortens. 6. This process continues for a brief period, until: 7. Action potential generation stops as ACh diffuses out of the synapse or is broken down by AChE. 8. The sarcoplasmic reticulum (SR) reabsorbs calcium ions, and the concentration of calcium ions in the sarcoplasm decreases. 9. When calcium ion concentrations near normal resting levels, the troponin-tropomyosin complex returns to its normal position. This change covers the active sites and prevents further cross-bridge interaction. 10. Without cross-bridge interactions, further sliding does not take place, and the contraction ends. 11. Muscle relaxation occurs, and the muscle fiber returns passively to resting length. What happens at the neuromuscular junction that induces muscle contraction? • Neuron communicates with muscle • neuron stimulates muscle fiber to generate action potential so that they can contract through release of ACH. • (motor units) nerves- innervate the muscle by penetrating the epimysium How do muscles enlarge through exercise? What happens during muscle hypertrophy? • Exercise increases the activity of muscle spindles and may enhance muscle tone. • As a result of repeated exhaustive stimulation muscle fibers develop a greater number of myofibrils and mitochondria a higher concentration of glycolytic enzymes and larger glycogen reserves. the net effect is enlargement or hypertrophy of the stimulated muscle. • Hypertrophy occurs in muscles that have been repeatedly stimulated to produce near maximal tension the intracellular changes that occur increase the amount of tension, the intracellular changes that occur increase the amount of tension produced when these muscles contract example: weightlifter bodybuilder. How do muscle behave as levers? Know the parts of a lever and the examples of the first-, second- and third-class lever system muscles given in class. Lever is a rigid structure that moves on a fixed point called the fulcrum. In the body each bone is a lever and each joint a fulcrum. Components: • Lever=bone
• Fulcrum=joint-fixed point • Applied Force=muscular force • Load=weight or resistance, trying to move or lift. FIRST CLASS LEVER Fulcrum in the middle • Applied force and load are on opposite sides of the fulcrum • This lever changes the amount of force transmitted to the load and alters the direction and speed of movement. • Very few 1 st class levers in the body • Ex: head and neck (Applied Force-muscles in the back of the neck, load-weight in the head, moving head backwards. ) Second-class lever • The load is between the applied force the fulcrum. • This arrangement increases force at the expense of distance and speed, the direction of movement remains unchanged • load in the middle-applied effort and fulcrum either side of the load • example: foot or leg • very few 2 nd class levers in the body Third-class lever • MOST COMMON LEVER IN THE BODY • the applied force is between the load and the fulcrum • this arrangement increases speed and distance moved but requires a larger applied force. • Ex: biceps What is so special about cardiac muscle? What are intercalated disks? What do they contain? Why? • Found only in the heart, striated involuntary muscle. • BOTH: smooth and skeletal fibers • Parasympathetic/sympathetic control • Single nucleus • Cardiac muscle cells cannot divide • Doesn’t rely on nervous system to start a contraction • • Intercalated disc: gap/cell junctions (holding cardiac muscles together using fascia adherents and desmosomes) -fast transmission between cardiac cells
Compare and contrast the origin, insertion, and action of a muscle. What is the belly of a muscle? Origin: • point of muscle attachment that remains stationary • Insertion points of muscle attachment that is movable Actions: • Agonist-prime mover • Antagonist-opposes action of agonist • Synergist -agonist assistant • Fixator-creating immovable base • Belly of the muscle: body of the muscle • the widest part of a muscle. the origin and insertion deal with the tendon attachments. With respect to origin and insertion, what happens to them when a muscle contracts? • When a muscle contracts insertion moves towards the origin. Why is it appropriate to think of muscles in opposite pairs? • Muscles work in pair, when one muscle shortens the opposite muscle lengthens • Good working between pairs of muscles allows for smooth controlled movement. • Ex: the biceps shorten to bend the elbow at the time its opposite muscle the triceps, lengthens to allow the movement to occur. CHAPTER 13 Sections covered from Martini: 13-1 Through 13-4. 1 How is the Nervous System organized starting with receptors ending with effectors?
The nervous system is subdivided into the: central nervous system (CNS) and peripheral nervous system (PNS). The CNS is composed of the brain and spinal cord. The PNS has afferent and efferent divisions. The afferent division consists of somatic and visceral sensory nerves. The efferent division consists of the somatic and autonomic nervous systems ; the autonomic nervous system consists of the parasympathetic and sympathetic divisions. 2.What does the CNS consist of? The PNS? CNS- Central Nervous System CNS consists of the brain and spinal cord. CNS processes and coordinates sensory input and motor output It is also the location of higher functions, including intelligence, memory, learning, and emotion. PNS- Peripheral Nervous System PNS consists of- all the peripheral nerves and nervous tissue outside the CNS
PNS provides sensory information to the CNS and carries motor commands from the CNS to peripheral tissues and systems PNS HAS 2 DIVISIONS: Afferent & Efferent – Remember SAME (Sensory[afferent], Motor[efferent]) AFFERENT- Carries sensory information to the CNS (Afferent division begins at receptors that monitor specific characteristics of the environment) Receptor: may be a sensory process, specialized cell/cluster of cells, or complex sense organ (such as the eye) EFFERENT- Carries motor commands from the CNS to muscles and glands (Efferent division begins inside the CNS and ends at an effector ) (your end point/your target) Effector: muscle, gland cell or another cell specialized to perform specific functions
3.What does the term Somatic mean? What is a somatic sensory receptor? Does information flow in the afferent or efferent direction here? How does this relate to motor vs. sensory neuron? Somatic - pertaining to the control of skeletal muscle activity (somatic motor) or sensory information from skeletal muscles, tendons, and joints (somatic sensory) Somatic sensory receptors - monitor skeletal muscles, joints. Information flows in the afferent direction here- its SENSORY information from the muscles, joints, etc. going to the brain. Information from a somatic sensory receptor alters the level of activity in a sensory neuron.
4.Where do we find visceral sensory receptors? Be familiar with visceral receptors in a reflex. What does Autonomic have to do with “visceral”? Visceral sensory receptors are found on internal structures such as smooth muscle, cardiac muscle, glands, and respiratory/digestive organs. AUTONOMIC NERVOUS SYSTEM The autonomic nervous system controls visceral functions . Automatically controls breathing, digestion, HR, excretion. Autonomic system is divided into PARASYMPATHETIC & SYMPATHETIC
5.What is an effector? Be familiar with both somatic and autonomic effectors. Effector- A muscle gland or other specialized cell or organ that responds to neural stimulation by altering its activity and producing a specific effect. Somatic effectors- are skeletal muscles Autonomic effectors- are smooth muscle, cardiac muscle, glands, and adipose tissue
6.Be able to label a neuron with the following parts: cell body, axon, dendrites, dendritic spines, axon terminal and buttons, axon hillock, myelin sheath, nodes of Ranvier – internodes, Niessl bodies, telodendrion. Nissl bodies are subcellular structures found in nerve cell bodies and dendrites. They consist of granular endoplasmic reticulum and ribosomes. Telodendrion- the terminal branches of an axon
7.Compare and contrast the three types of neurons and be familiar with the examples of where each is found in the human body.
Neurons are classified functionally into 3 categories: 1) SENSORY NEURONS 2) MOTOR NEURONS 3) INTERNEURONS SENSORY NEURONS -From the afferent division of the PNS -Deliver information about the external or internal environment to the CNS -Axons of sensory neurons are called afferent fibers & they extend between a sensory receptor and the spinal cord or brain. Somatic sensory neurons - transmit info about the outside world and our position within it. Visceral sensory neurons - transmit info about internal conditions and the status of other organ systems. Receptors are either the processes of specialized sensory neurons or cells monitored by sensory neurons. There are 3 categories of receptors: 1) INTEROCEPTORS- (inside) monitor digestive, respiratory, cardiovascular, urinary and reproductive systems. - Provide sensations of deep pressure, pain, taste.
2) EXTEROCEPTORS- (outside) provide information about the external environment in the form of touch, temperature, and pressure sensations and the more complex special senses of sight, smell and hearing. 3) PROPRIOCEPTORS- (one's own) monitor the position and movement of skeletal muscles and joints. Somatic sensory neurons carry information from exteroceptors and proprioceptors. Visceral sensory neurons carry information from interoceptors. MOTOR NEURONS -Form the efferent division of the NS - Stimulate or modify the activity of a peripheral tissue, organ, or organ system - Axons traveling away from the CNS are efferent fibers 2 EFFERENT DIVISIONS OF THE PNS Somatic nervous system - has somatic motor neurons that innervate skeletal muscles. Most activities of the SNS are consciously controlled. Cell bodies of motor neurons lie inside the CNS and their axons extend to the neuromuscular junctions that control skeletal muscles. Autonomic nervous system - has visceral motor neurons that innervate peripheral effectors other than skeletal muscles There are 2 groups of visceral motor neurons
1 group has cell bodies inside the CNS The other has cell bodies in peripheral ganglia NEURONS IN CNS CONTROL NEURONS IN THE PERIPHERAL GANGLIA Preganglionic fibers - Axons extending from the CNS to a ganglion Postganglionic fibers - Axons connecting the ganglion cells with peripheral effectors WE HAVE LITTLE CONSCIOUS CONTROL OVER THE ACTIVITIES OF THE ANS. THEY ARE AUTOMATIC INTERNEURONS -Located between the sensory and motor neurons within the brain and spinal cord -Analyze sensory input and coordinate motor output -More complex the response to a stimulus=greater number of interneurons involved INTERNEURONS CAN BE EXCITATORY OR INHIBITORY BASED ON THEIR EFFECTS ON THE POSTSYNAPTIC MEMBRANES OF OTHER NEURONS 8.What is a synapse? Know they different types. Synapse - site of intercellular communication between a neuron and another cell. Synapses can be CHEMICAL or ELECTRICAL.
CHEMICAL SYNAPSE (aka vesicular synapse) These are the most abundant type of synapse , and they involve the passage of neurotransmitters between cells. Neurotransmitters released at the presynaptic membrane of an axon bind to receptor proteins on the postsynaptic membrane. Neurotransmitter triggers a temporary change in the membrane potential of the postsynaptic cell that may or may not cause an action potential depending on how strong it is Only the presynaptic cell releases neurotransmitter= ONE WAY COMMUNICATION EX: Neuromuscular junctions are considered CHEMICAL SYNAPSES because they release (ACh) ELECETRICAL SYNAPSES (aka non vesicular synapse) These types of synapses are relatively RARE. Found between neurons in both CNS & PNS Transmit electrical signals (IONS) Pre and postsynaptic membranes are bound tightly together – they form GAP JUNCTIONS that permit the passage of ions between two cells Because cells are composed this way they function as if they share a common membrane, and the nerve impulse crosses from one neuron to the next without delay CAN CONVEY NERVE IMPULSES IN EITHER DIRECTION- BIDIRECTIONAL
9.What is an interneuron? Where do we find it? Function? ALREADY ANSWERED THIS ABOVE ^^ 10.The Neuroglia: Know all of these for CNS and PNS. What is the blood brain barrier and which glia are involved in its composition? Neuroglia - cells of the central nervous system and peripheral nervous system that support and protect neurons ; also called glial cells. There are 4 different types of neuroglia in the CNS There are 2 different types of neuroglia in the PNS NEUROGLIA IN THE CNS 1) Astrocytes 2) Oligodendrocytes 3) Microglia 4) Ependymal cells ASTROCYTES- largest and more numerous FUNCTIONS - control interstitial environment : they have pedicels (feet) that increase their surface area, help promote uptake of ions, neurotransmitters, metabolic by-products - maintain the blood brain barrier: chemicals secreted by astrocytes maintain the BBB that isolates the CNS from the general circulation
-form 3D framework for the CNS - packed with microfilaments that extend across the cell, provide mechanical strength and form a structural framework to suppose neurons of the brain and spinal cord -repair damaged nervous tissue - make structural repairs, stabilize the tissue and prevent further injury by producing scar tissue at the injury site -guide neuron development - involved in directing the growth and interconnection of developing neurons through secretion of chemicals OLIGODENDROCYTES Have smaller cell bodies and fewer cytoplasmic processes Processes contact the axons/cell bodies of neurons and tie clusters of axons together FUNCTION: cooperate in forming the myelin sheath within the CNS , large areas wrapped in myelin are called internodes. MICROGLIA Smallest neuroglia possesses slender cytoplasmic processes w many fine branches Microglia are phagocytic cells of the CNS- they engulf cellular debris and wastes. They also phagocytose VIRUSES, MICROORGANISMS, AND TUMOR CELLS - to protect the CNS. CNS only contains about 5% of neuroglia but percentage increases dramatically when the CNS is infected or injured. EPENDYMAL CELLS Are cuboidal to columnar in shape. Have slender processes that branch out and make contact with neuroglia in the surrounding nervous tissue May act as receptors monitoring the composition of the CSF (cerebrospinal fluid)
In adults, cilia and microvilli are found on the apical surface of ependymal cells. Cilia helps the CSF circulate and the microvilli are involved in the absorption of CSF NEUROGLIA IN THE PNS 1) SATELLITE CELLS 2) SCHWANN CELLS SATELLITE CELLS Surround neuron cell bodies in ganglia Regulate the exchange of nutrients and waste products between the neuronal cell body and extracellular fluid Regulate O2 and CO2 nutrient and neurotransmitter levels Isolate the neuron from stimuli not intended to pass from neuron to neuron SCHWANN CELLS (aka neurolemmocytes) Surround all axons in the PNS Myelinate peripheral axons – (myelin sheath) Participate in repair after injury
BLOOD BRAIN BARRIER (BBB) The blood brain barrier is formed by capillary endothelial cells that are interconnected by tight junctions . These junctions prevent materials from diffusing between cells (CREATE A BARRIER) ONLY lipid soluble compounds diffuse across the endothelial cell membranes and into the interstitial fluid of the brain and spinal cord. Have few pinocytotic vesicles - limits movement of large molecular weight compounds into the CNS. (UREA) ASTROCYTES ARE INVOLVED IN MAINTENANCE OF BBB. CHEMICALS SECRETED BY ASTROCYTES MAINTAIN THE BBB.
11.Compare and contrast white and gray matter. WHITE MATTER Consists of columns of nerves called FUNICULI - posterior white column -located between the post. White horns and the post. Median sulcus - anterior white column -located between the anterior horns and the anterior median fissure - lateral white column -located between the anterior and posterior columns Each column is organized into TRACTS Tracts are composed of axons that share functional and structural characteristics A tract carries either sensory or motor commands
Axons within a tract have the same diameter, myelination, and conduction speed . They relay information in the SAME DIRECTION Small commissural tracts - carry sensory/motor signals between segments of the spinal cord Large tracts -connect the spinal cord with the brain GRAY MATTER Cell bodies of neurons within the gray matter of the spinal cord are organized into groups called nuclei that have specific functions. Sensory nuclei - receive and relay sensory info from peripheral receptors, such as touch receptors in the skin Motor nuclei - send motor commands to peripheral effectors, such as skeletal muscle
They contain posterior (dorsal) horns and anterior (ventral) horns Posterior (dorsal) horns - contain somatic and visceral sensory nuclei Anterior (ventral) horns - contain somatic motor neurons Lateral horns (FOUND ONLY BETWEEN SEGMENTS T1 & L2) – contain visceral motor neurons Gray Commissure - consists of axons crossing from one side to the other (DECUSSATING) 12. Know the distinguishing terminology for PNS and CNS: Tract Vs. Nerve, ganglion vs. nucleus, PERIPHERAL NERVOUS SYSTEM (PNS) Neuron cell bodies in gray matter are called GANGLIA Axons are bundled together in white matter are called NERVES
CENTRAL NERVOUS SYSTEM (CNS) Neuron cell bodies in gray matter are called NUCLEI Axons bundled together in white matter are called TRACTS Chapter 14
What is the gross anatomy of the spinal cord? The spinal cord extends inferiorly from the base of the brain along the vertebral canal. BEGINS AT FORAMEN MAGNUM AND ENDS AT THE CONUS MEDULLARIS (BY L1-L2) https://youtu.be/SoSFjaZ-lMs Where does it originate? • Foramen magnum(brainstem) of the skull to the inferior border of the first lumbar vertebrae L1 and L2. How many segments? What are the segments? • 31 segments • A letter and a number designation identify each segment. For example: c3 is the third cervical segment • 8 cervical , 12 thoracic , 5 lumbar, 5 sacral amd 1 coccygeal spinal nerve. 7 CERVICAL BUT THERE IS 8 SPINAL NERVES BC IT STARTS ON TOP OF C1. L1- STARTS UNDERNEATH
Where does the cord end? What do we call this?
• The spinal cord tapers and forms a cone-shaped tip called the conus medullaris, which is located at or inferior to the level of the first lumbar vertebra (L1) • Extending within the vertebral canal from the inferior tip of the conus medullaris is the filum terminale (“terminal thread”) HORSE TAIL . The filum Terminale extends from to the dorsum of the coccyx, where it connects the spinal cord to the first coccygeal vertebra How does it go on? (Conus medullaris, filum Terminale, cauda equina?? The filum Terminale and the long ventral and dorsal roots are called the cauda equina because this structure reminded early anatomists of a horse’s tail (becomes part of the coccygeal ligament. . The enlargements-where and why?
• From cervical enlargement -which supplies nerves to the pectoral girdle and upper limbs • Lumbosacral enlargement – which supplies nerves to the pelvis and lower limbs • Caudal to the lumbosacral enlargement, the spinal cord tapers and forms a cone shaped tip called the conus medullaris which is located at or inferior to the level of the first lumbar vertebra(L1) • Extending within the vertebral canal from the inferior tip of the conus medullaris is the filum Terminale . The filum Terminale extends from L1 to the dorsum of the coccyx, where it connects the spinal cord to the first coccygeal vertebra. • Cauda equina: bundle of spinal nerve roots arising from the lumbosacral enlargement and medullary cone of the adult spinal cord: they extend caudally inside the vertebral canal end route to lumbar and sacral segments. How many spinal nerves are, where in the vertebrae do they form? How are they organized? Look at image above for all spinal nerves • 8 cervical (C1-C8) nerves emerge from the cervical spine (neck) • 12 thoracic (T1-T12) nerves emerge from the thoracic spine (mid back) • 5 lumbar (L1-L5) nerves emerge from the lumbar spine (lower back) • 5 sacral (S1-S5) nerves emerge from the sacrum (the triangular bone at the base of the spine) • 1 coccygeal nerve emerges from the coccyx (the tailbone) • Each spinal nerve associated with a pair of dorsal root ganglia.( containing sensory and neuron cell bodies. Compare and contrast dorsal root with ventral root? Dorsal -sensory Motor sensory or visceral sensory – goes to the brain/spinal cord. Dorsal root ganglion: every spinal segment is associated with a pair of dorsal root ganglia that contains cell bodies of sensory neurons (only exceptions are: c1 and the 1 st coccygeal vertebra, where some people lack dorsal roots and the associated dorsal root ganglia.)
• Innervate the back • On both sides of the spinal cord – contain afferent axons of the sensory neurons in the dorsal root ganglion • Thicker than ventral roots Ventral root • Innervate the front • Leaves the spinal cord • Contains the efferent axons of somatic motor neurons and at some levels efferent visceral motor neurons that control peripheral effectors.
What is a ramus? From where does one form? all spinal nerves have two branches : dorsal and ventral ramus The spinal cord gross anatomy of a cross section: know the anterior from the posterior. (watch video on youtube) DORSAL IS SENSORY , VENTRAL IS MOTOR. The posterior dorsal horns contain somatic and visceral sensory nuclei, and the anterior vertebral horns contain somatic motor neurons. Anterior horns are largest in cervical and lumbar regions of the spinal cord. White matter: peripheral white matter Contains myelinated axons organized into tracts and columns The amount of white matter decreases as you move caudally within the spinal cord. Grey matter: H shaped/BUTTERFLY SHAPED , called horns – project towards the outer surface of the spinal cord • nerve cell bodies, glial cells. And unmyelinated axons. • Surrounds the central canal • Sensory nuclei receive and send information from peripheral receptors • Motor nuclei send motor commands to Peripheral effectors. Be able to label the anterior medium fissure, (12) the posterior medium sulcus (8).
The anterior medium fissure and the posterior median sulcus divide the spinal cord into left and right halves. Sample from the book! How do cervical, thoracic, lumbar, and sacral sections compare with respect to gray matter? Why? What the thell is she asking???? Idk dude Grey matter increases as you move down the spinal cord . White matter decreases as you move down the spinal cord.
How are spinal meninges organized? 3 MENINGEAL LAYERS dura matter (TOUGH MOTHER) = is a tough fibrous layer that forms the outermost covering of the spinal cord and brain. STABILIZES THE SPINAL CORD Arachnoid matter: the arachnoid matter, middle meningeal layer is composed of a simple squamous epithelium. The arachnoid matter lines the inner surface of the dura matter. HAS TO WITH CSF. Pia matter:The surface of the CNS is covered with a connective tissue membrane, the pia matter. The pia matter closely follows the contours of the spinal cord. HAVE BLOOD VESSELS. Pia matter, subarachnoid space (CSF FLOWS THROUGH HERE), arachnoid matter, dura matter, epidural space. • The spinal meninges cover and protect the spinal cord and spinal nerve roots. Distal to each dorsal root ganglion, the sensory and motor fibers form a spinal nerve that exits the intervertebral foramina.
What are some differences seen here between spinal and cerebral meninges? Spinal meninges: • line the vertebral canal • provide protection • stabilization, • nutrition • And shock absorption to the spinal cord. Cerebral/cranial meninges: ( have 3 layers, dura, arachnoid and pia. )
• Responds to stimuli with greater adaptability • Act as shock absorbers preventing contact with the skull bones • Brain floats in CSF reducing effects of forces. What is the epidural space? what are the denticulate ligaments? Supporting fibers that extend laterally from the surface of the spinal cord tying the pia mater to the dura mater and providing lateral support for the spinal cord. Denticulate ligaments- help anchor the spinal cord in position.
What are the 2 functions of the Spinal cord? • Electrical communication to and from the brain • Locomotion • Integrates and processes information • Can function with the brain or independently
What are the parts of a reflex arc ? 1. Step 1: Stimulation and activation of receptor . There are many types of sensory receptors Each receptor has a characteristic range of sensitivity; some receptors, such as pain receptors, respond to almost any stimulus. These receptors, which are the dendrites of sensory neurons, are stimulated by pressure, temperature extremes, physical damage, or exposure to abnormal chemicals. Other receptors, such as visual, auditory, or taste receptors, are specialized cells that respond to only a limited range of stimuli. 2. Step 2: Activation of a sensory neuron . Information is carried in the form of an action potential along an afferent fiber. In this case, the axon conducts the action potential into the spinal cord through one of the dorsal roots. 3. Step 3: Information processing in CNS . Information processing begins when the neurotransmitter released by the axon terminals of a sensory neuron reaches the postsynaptic membrane of a motor neuron or interneuron. In the simplest reflexes, this processing is performed by the motor neuron controlling the peripheral effectors. In more complex reflexes, one or more interneurons are located between the sensory and motor neurons, and both serial and parallel processing occur. This type of information processing selects the appropriate motor response through the activation of specific motor neurons. 4. Step 4: Activation of a motor neuron . When a motor neuron is stimulated to threshold, it conducts an action potential through the ventral root of a spinal nerve to the peripheral effector organ. 5. Step 5: Response by effector . Activation of the motor neuron causes a response by a peripheral effector, such as a skeletal muscle or gland. Reflexes play an important role in opposing potentially harmful changes in the internal or external environment.
What are plexuses? From where do they originate? Give the major nerve they innervate and the function of each. - groups nerves based on their functionality: • Cervical Plexus – the cervical plexus represents the continuation of the upper cervical spinal nerves that innervates the muscles of the neck and diaphragm. • Brachial Plexus – the brachial plexus innervates the muscles of the pectoral girdles and upper limb. • Lumbar Plexus – the lumbar plexus represents the continuation of lumbar spinal nerves that give innervation to the lower extremities • Sacral Plexus – the sacral plexus gives innervation to the back of the thigh, leg, bottom of the foot, as well as the pelvis