ANFS140 Exam 1 Study Guide
ANFS140 Exam 1 Study Guide 140
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This 43 page Study Guide was uploaded by Rachel Schmuckler on Monday March 14, 2016. The Study Guide belongs to 140 at University of Delaware taught by Dr. Robert Dyer in Spring 2016. Since its upload, it has received 86 views. For similar materials see Functional Anatomy of Domestic Animals in General Science at University of Delaware.
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Date Created: 03/14/16
STUDY GUIDE EXAM 1 ANFS140 Organ Systems and Tissue Types Organ Systems Each system is anatomically distinguishable, but integrated together 11 major systems o Discrete Systems: we can see and feel it Skeletal Muscular Digestive Respiratory Urinary Reproductive Integumentary Skin Protect Secrete Thermoregulate Immunoregulate (“third arm of the immune system”) o Releases hormones from endocrine system that circulate causing inflammation) Special senses (ears, eyes, nose) o Integrative Systems: distributed across and impacting all discrete systems Nervous Controlled by hypothalamus Circulatory Endocrine Organ Size by Mass of Body 1 livre G I heatr nrv os u lung 0 .3 % allhtrs 2 % 2 % 2 % 1 % 1 % s nk 7 % Muslce blo o d 4 3 % 7 % s lto n 1 6 % Adipo s e 1 9 % Muscle fat bones Increasing age causes muscle to turn to fat Blood = 7% of body weight In lab, findings will show the integumentary system as the largest in the body because it can all be taken off, where muscle cannot fully be removed and weighed. In the dairy industry, the goal of producers is to overfeed the cattle when lactating to increase the percent fat, maximizing milk production Causes obesity related problems (Diabetes II, Cardiovascular Disease, Joint Diseases) because as the adipose tissue mass expands, the inflammatory response is triggered, causing damage and resistance General Chemical Composition of Body K N,,Cl,Mg N C a P 1 % 3 % 1 %1 % H 1 1 % C 1 7 % O 6 6 % Ca and P from skeletal system o Ca can be soluble (in every cell) or solid Oxygen and Hydrogen located everywhere because it is an integral part of amino acids, fats, and sugars 2 o O2 also in water, body is 70% water Carbon in amino acids, sugars, fats Nitrogen in amino acids (proteins) Water Composition 1kg=1L 10-12% water loss is fatal 70% water by body weight 450kg horse has about 300L of water. A horse usually rids 120L of water a day that must be replaced. Compartments of Body Water Extracellular water = 35%, intracellular water = 65% Water exchange in/out of cell at 1000times/second Dehydration occurs first in the extracellular environment, then the intracellular environment Four Tissue Types Epithelium: covers any surface (external, internal) Connective: adipose, bone, cartilage (hyaline, elastic, fibrocartilage), fibrous (loose, irregular dense, dense fibrous) o Single stem cell that populated the embryonic body o Stem cells divide to daughter cells to form connective tissue Muscle: skeletal, smooth, cardiac o Skeletal: moves the skeleton o Smooth: visceral, retains dynamic movement o Cardiac: only muscle tissue in the heart o Striated = cardiac and skeletal Nerve: composed of different types of tissue o Neurons are the functional units o Neurons hooked together to organize the system Every organ comprised of different types of tissue Cell sources for each type of tissue are very different from one another Epithelium Line surfaces Skin, forms all glands (regardless of type, even the mammary gland of the cow), lines ducts, organs, lines vascular system Protect Secretes hormones, immunities, coagulants (scabs) and anticoagulants (prevents blood clots) Synthesize Relates to synthetic and secretory functions 3 Classification: o Anatomic cell shape Squamous – flat Cuboidal – cube-like Columnar – column-like Can only be simple o Number of cell layers Simple – 1 layer Stratified – multiple layers Most common with squamous Pseudostratified – 1 layer appearing as multiple layers Transitional – transforms from stratified appearing to a simple cell layer From simple squamous to cuboidal that is piled up on itself In organ systems that need to expand and contract (i.e. bladder) o i.e. Simple Squamous Alveoli, vascular tree, kidney o i.e. Simple Cuboidal Rare Small bronchi, secretory ducts of lacrimal gland/pancreas/kidney/sweat glands/female reproductive tract o i.e. Simple Columnar Trachea, gut, kidney o i.e. Pseudo-stratified Airway, testes ducts 4 Anatomic Structures are changing all the time Stratified squamous o Can get thicker (i.e. callouses) o Skin – the number of layers in different areas changes o Bottom layer are stem cells that create daughter cells that move upward Transitional is just an appearance (not actually stratified) Pseudostratified is technically a layer with the nuclei located at different ends, causing different shapes o In the end, they are all somehow attached to the base layer Epithelial tissue turns over constantly 120 days for skin 5 days for gut ~160 days for stomach Epithelium covers surfaces and forms surface barriers Membrane lies attached to another acellular membrane called the basal lamina (basement membrane) All epithelia cells attach to the basal lamina regardless of location 5 Basement membrane separates epithelium from underlying tissue Left Photo: Bowel, lumen on top, columnar epithelium Right: integument system, bottom where they look curvy are the stem cells that are pushing daughter cells upward, stem cells firmly attached to acellular membrane Would repair dependent upon deposit of basement membrane o Stem cells sitting on the side of a wound speed up the rate of making daughter cells at the edge of a wound. Then, those daughter cells deposit more basement membrane along the wound before those stem cells can migrate across the wound and cover it up. o Varicose ulcers, diabetic wounds People cannot deposit the membrane so the wounds won’t heal 6 Cell Domains Important when studying disease processes Photos are a cross-section of a trachea, pseudostratified epithelium Apical: outer domain, points toward surface Lateral: side of the cell Basal: inner domain, attaches to basal lamina Apical Domain Microvilli o Fingerlike projections o Size, number, length, shape changes depending on cell function o Increase surface area of apical domain o Enhance absorptive function by keeping cells in contact with materials o Bowel, GI tract o Diseases/illnesses attack stem cells causing them not to function properly No daughter cells are made, top is recycled, surface has less epithelial cells, microbes get inside and cause a fatal event, remaining cells spread out in attempt to cover surface, microvilli shorten, no absorption o Form as the cells migrate towards the surface o As microvilli move upward, they increase in # and length 7 Steriocilia o Cells that line the ducts of the male gentical tract o Long in length o More like microvilli in structure and function o Absorption of water Tons of bulls/stallions – tons of semen, tons of water secreted, water needed to be absorbed to conserve water and concentrate ejaculate o Looks like a wet paintbrush Cilia o Hairlike projections that project into the lumen o Ear ducts, respiratory tract ducts o Wavelike fashion to move stuff from lower lung to pharynx to clean/maintain sterility of the lung o Move independently of our breath o Chief modal modifications of apical domain o Millions per apical zone o Beat in unidirectional fashion to move secretions o Coordinated motion o Tons of synthesis necessary to make new cilia 8 o Mucus sits on top of cilia, the cilia beat in coordinated fashion moving it from lower lung to high respiratory tract, causes us to swallow o Dirty air mixed with water and bacteria enter the lung with every breath Excessive bacteria in lower lung = pneumonia Surface of air-gas-exchange is sterile thanks to the mucus blanket and cilia activity that propels the mucus back up towards the pharyx Structure: Microvilli and Steriocilia Apical domain along the bottom of the photo Skeletal system o Cords of actin filaments packed into the wall to provide rigidity/structure o Myosin filaments act with actin to form a contractile unit Structure: Cilia 9 9 plus 2 microtubule arrangement = standard structure for modal agents (i.e. flagella, sperm cell, bacteria) o Cilia have tons of these in cross sections o Made of tubulin Red and blue tubules that assemble together and line the entire length of the cilia The tubules contract together Attached As one moves, it pulls the other in that direction Lateral Domain Modifications Zonula Occludens o Circumferential band of close cell to cell adhesion closest to apical surface o Creates impermeable, selectively permeable barrier between cells o Gut wall o Not an attachment mechanism o Multiple proteins Changing the structure of the proteins affects the strength capabilities of the attachments o Think Velcro! Zonula Adherens o Circumferential band of tight cell to cell adhesions o Attaches lateral domains of cells firmly together o Zone of adhesion – tightly attaches the epithelial cells The reason we can move our skin around o Easily modified with changes Desmosomes 10 o “spot weld” like cell to cell lateral domain attachments o Buttons between the walls of the cells that attach between cells o Tight adhesions o Randomly distributed around lateral domain Zonula Occluden o Calcium dependent, in equilibrium with the body o Proteins will change over time and after synthesized Strength constantly changing Inflammation and diets can change the composition of proteins Can increase/decrease permeability layer to affect which things (inflammatory inhibitors, etc) get into these cells Poison ivy: blisters from inflammatory response because we are allergic to the poison ivy plant o Actin filaments are the skeletal system of all cells Attached to the proteins that make up adhesion structures Basal Domain Modifications Hemidesmosomes o Scattered throughout basal domain o Similar structure to half a desmosome o Attach basal domain firmly to basement membrane o Reason we can pick up our skin and have it stay attached to the underlying connective tissue o Prevents epithelia of the bowel from being stripped every time ingesta moves through o Synthesize the rebar/cement of basement membrane 11 o Anchoring filaments – run fibrous tissue through the cement and wrap it around the fibrous tissue under epithelium to tie basement membrane down to deep collagen fibrous tissue o Loop through basement membrane and around collagen fibers of underlying fibrous tissue o Function to tie basement membrane to fibrous tissues o Attaches basal domain to basement membrane Glands Epithelial tissue Tubular – tube-like o Simple: sweat gland, female uterus to nourish fetus (early part of estrus cycle) o Simple coiled: longer simple tubular gland that lengthens as demand increases Coiling in uterus driven by estrogen (later part of estrus cycle) o Simple branched: more complex than coiled (latest part of estrus cycle) o Estrus cycle changes gland shape every 21 days as the cycle goes on Acinar/Alveolar – balloon or grape-like o Compound tubuloacinar: multiple simple branched acinar with aduct system Salivary galnds, mammary glands, lacrimal glands, pancreas o Compound: mixed structures to deal with the crazy functions in these organ systems (i.e. pancreas) 12 Fibrous Connective Tissue Connective Tissue Adipose Blood Bone Cartilage o Hyaline o Elastic o Fibrocartilage Fibrous Tissue o Loose o Irregular Dense o Dense Fibrous Mesenchymal Cell Undifferentiated cell that gives rise to all other cell types in connective tissue Common ancestral cell Adipose = adipocyte, pre-adipocyte or lipoblast Blood = myeloid and erythroid series Bone = osteoprogenitor and osteoclasts Cartilage = chondrocyte o Hyaline o Elastic o Fibrocartilage Fibrous tissue = fibroblast o Loose o Irregular dense o Dense fibrous Two Components of Fibrous Connective Tissue 13 Cellular Component o Changes with different types of connective tissue cells o Fibroblasts Permanent Endemic cell type Makes the matrix and fibrous component of fibrous connective tissue o Mesenchymal Stem Cells – give rise to fibroblasts o Immune Cells Wander in and out of fibrous tissue continuously Immune Surveillance: exit the vascular tree, migrate through fibrous connective tissue, and back into the vascular tree to recirculate elsewhere Monitor for infectious agents/tumors/damaged matrix Located in lymph nodes, bone marrow Extracellular Component o Matrix Very slippery Hyaluronin – long sugars, oil-like, secreted by joints Proteoglycans – proteins with sugars attached o Fibrous component – collagen fibers, like cable or rope o Matrix and fibrous components are generated by the cellular component and maintained by constant reabsorption/re- synthesis by cell components Constantly regenerating because they are always damaged with movement/metabolism/bacterial viruses Loose Fibrous Connective Tissue Fibroblasts High content of extracellular matrix – tons of hyaluronin and proteoglycans Low content of collagen fibers Spiders in a spider web o Spiders = fibroblasts, making the fibers o Spider web = collagen fibers o If honey dumped into the spider web, the honey is the hyaluronin and proteoglycans o Ants = immune cells climb along the web/honey looking for errors Attaches skin to underlying tissue 14 Irregular Dense Fibrous Connective Tissue Fibroblasts Moderate content of extracellular matrix Moderate content of collagen fibers Matrix (oil) decreases as collagen fibers (rope) increase Tangled mess Dermis Gives the skin some strength Dense Regular Fibrous Connective Tissue Fibroblasts Tendons and ligaments Packed full of collagen fibers 15 Enormous strength High numbers of collagen fibers, little matrix Rigidly arranged collagen fibers Collagen Similar to thread 24 different molecular types (numbered 1 to 24) o Numbered based on when they were founded The types of collagen that are made change depending on the needs of the body, highly variable Tropocollagen Subunit Molecule synthesized by the fibroblast to create the collagen fibers Strength of collagen fibers comes from the staggered arrangement of subunits (about 30% crossover between fibers) Triple helix structure o 3 polypeptide chains (amino acid sequences) 16 o Synthesized by fibroblast, wrapped together in this structure to make tropocollagen subunits o Scurvy Skin falls apart, loss of elasticity Hemorrhage, ulcers Loss of the tropocollagen subunit structure Vitamin C deficiency, causes issues with the amino acids that make the polypeptide chains curved Substance that gives the matrix an oily feel Hyaluronin – green, long polymer of sugar, very slippery Fibroblasts synthesize proteoglycan o Glycosoaminoglycan (red, sugar) + protein core (yellow) Composition of glycosoaminoglycans shifts, causing a shift in the composition of the matrix (oil-matrix to wax-hyaline cartilage) Adds structure to any connective tissue Types of Glycosoaminoglycans Attached to Protein Core Hyaluronan – synovial fluid Chondroitin 4 sulfate – cartilage, bone Chondroitin 6 sulfate – cartilage and bone Dermatin – skin and blood vessel wall Keratin sulfate – bone cartilage Heparin sulfate – basement membrane o Also made by epithelial cells 17 Extracellular water is electrostatically attached to the matrix of fibrous connective tissue Glycosoaminoglycans are heavily negatively charged Water comes out of the cell and the positive end of the polar molecule attaches to the negative charge of the glycosoaminoglycans Amount of water attached to the glycosoaminoglycans depends on the type of sugars attached Cells produce tons of hormones/growth factors/proteins which are also charged. As they are synthesized, the factors are also attached to the matrix Matrix acts as a reservoir of water, growth factors, proteins, and nutrients that is held together electrostatically Constant equilibrium/interchange between extracellular and intracellular environment of the cells (fibroblasts or immune cells) 18 No matter what kind of connective tissue, the main cell type is a fibroblast Above photo is a typical structure for a fibroblast o Specific structure to attach to collagen fibers and glycosoaminoglycans o Manufactures all the parts of the matrix o Makes collage Collagen fiber attached to the fibroblast as well Intra and extracellular components shown above Elastic Tissue Very similar to fibrous connective tissue i.e. inside the aorta Fibroblast, matrix, elastin o Fibroblast makes elastic fibers as well as collagen fibers Varying amounts of elastic tissue present in all types of fibrous connective tissue Brown = elastic fiber Extracellular Component of an Elastic Fiber 1 molecular type o Multiple elastin subunits are cross linked together to form fibers o Unique amino acid structure desmosine that gives elastin its elastic quality Desmosine (and isodesmosine): covalently bonds elastic fibers together, amino acid Copper deficiency – copper is a cofactor that makes isodesmosine, copper deficient animal doesn’t have isodesmosine synthesis in elastin monomers, fibers aren’t linked together very well 19 Aneurysm – elastic tissue ruptures (i.e. uterine wall) and bleed out Structure Unstretched Each pink string is a fiber Stretched Copper deficiency causes tearing when stretched Wall of aorta If the aorta can’t stretch, the pressure inside will increase rapidly causing hypertension Looks like regular dense fibrous connective tissue Dark pink = fibroblasts (making hyuronin, elastic fiber, glycosoaminoglycans) o If the fibroblasts start making collagen fibers instead of elastin, the tissue won’t stretch EXAM QUESTION!! 20 Cartilage Connective Tissue Two components (same as fibrous connective tissue_ Cellular component o Chondroblast Early chondrocyte – endemic cell type (progenitor cell) Slow process Permanent Lie outside of cartilage body, divide under fibrous layer of perichondrium to generate chondrocytes Cell stage between mesenchymal and chondrocyte, divide and daughter cells become chondrocytes Synthesize little matrix o Chondrocytes Mature cell in series that synthesizes and deposits extracellular component of cartilage Form lacunae by synthesizing tons of matrix to bury themselves in cartilage “Maintain the integrity of cartilage” by sitting in the lacunae Extracellular component o Matrix Hyaluronin, proteoglucans o Fibrous component Collagen fibers: low to moderate depending on the type of cartilage Elastic fibers: only in elastic cartilage (ear, epiglottis) 3 Types – all made of chondrocytes (stem from mesenchymal cells) Hyaline cartilage o Most common type of cartilage in the body o Joint surfaces, trachea, bronci and layrynx, nasal septum 21 o Sharks, embryos o High content of matrix, low content of collagen fibers = waxy substance o Cartilage ossified into bone, hyaline cartilage left over Each dark circle = chondrocyte Cells live in lacunae (lighter line around the chondrocytes) Collagen fibers, hyaluronin, proteoglycans being synthesized Dark pink line at the top = epithelia Light pink = irregular dense fibrous connective tissue Dark purple area = hyaline cartilage Blown up photo in the circle Cell inside lacunae inside matrix Chondrocytes synthesizing a different glycosaminoglycan than if it were a fibroblast synthesizing in fibrous connective tissue = reason it is wax-like Elastic cartilage o Moderate content of extracellular matrix (=hyaline) o Moderate content of elastic fibers, no collagen fibers o Relatively rare in body – epiglottis, aorta, pinnae of the ear 22 Fibrocartilage o Between the vertebral disks of the spine, between the bones of the skull, menisci of the knee o Moderate content of extracellular matrix (=hyaline) o Moderate content of collagen fibers (>hyaline) o Still some matrix o Bones knitted together by fibrocartilage to the point where they can’t articulate anymore – located between the sutures of bones (i.e. skull) 23 (Proteoglycan arrow is wrong!) Cartilage Structure 24 Little collagen, tons of matrix Lacunae with two cells inside are an insogenous group (perfectly identical, daughter cells of one cell) Lacunae with one cell is a chondrocyte Chondroblasts sit on the outer edge of the cartilage Perichondrium: membrane that sits around the cartilage o Structure is different with different types of cartilage o Does not cover articular surfaces Interstitial collagenous growth o Maintains integrity of cartilage o Replace old cartilage with new (versus appositional collagenous growth) Cartilage is never vascularized – vascularization of any cartilage causes it to ossify into bone Nutrition of cartilage through diffusion of nutrients in/out of the extracellular matrix More diffusion = more extracellular matrix synthesized and secreted by a chondrocyte = thickening of cartilage Matrix is a hydrostatic force (similar to the analogy of the sponge of blue dye in water) o Sponge full of blue due o Sponge into water 25 o Squeeze sponge o Blue dye out into water o Release sponge o Water back into sponge o Squeeze and release, etc. Put force on your leg, matrix contracts, step off of your leg, matrix expands o When the matrix is released, water and nutrients rush back into the matrix (comes from the synovial fluid) Joint capsule secretes hyaluronin, sugars, fats, water, salts, amino acid Width of cartilage changes in response to mechanical forces Build cartilage – exercise o Too much exercise will damage the cartilage Matrix wears out, collagen fibers can’t take the force, matrix fractures Lose cartilage – cast + non-weightbearing Bone Connective Tissue 4 types of cells Mesenchymal Cell Osteoprogenitor cell Osteoblast o Cell division o Synthesize and secrete bone o Deposit matrix to form lacunae Osteocyte o Buried in bone matrix o Intercannaliculi: arms projecting off of osteocyte that travels through the matrix to attach to another osteocyte in a different lacuna Osteoclast o Derived by fusion of monocytes (white blood cells) = multinucleated syncytium o Resorbs extracellular components of bone Hyaluronin, proteoglycans, water, collagen, calcium (hydroxyapatite), HCl 26 27 Nutrients enter the bone in arteries that pass through the dense bone – nutrient foramens Can enter in the epiphysis, diaphysis, or metaphysis Artery splits into branches once inside the bone that run proximally and distally along the length of the bone Eventually penetrate back into the bone that later branch and run up and down the length of the dense bone (distribute nutrients, remove waste) Blood supply is centrifugal (blood flow in, but the rest of the flow is from the center outwards) Pass through periosteum through dense bone via nutrient foramen through endosteum to enter cancellous bone area up and down marrow cavity pass back into endosteum and dense via the Volksman’s Canal up and down the length of the dense bone via the Haversian’s Canal meet osteocytes in lacunae to deliver nutrients 28 Underneath the endosteal membrane, there are circumferential lamellae (layers of bone) o Mesenchymal stem cells osteoprogenitor cells osteoblasts o Outer layer of irregular dense fibrous connective tissue that has fibroblasts and mesenchymal stem cells (that differentiate into osteoprogenitor cells and then to osteoblasts) o Inner layer of osteoblasts Sit on the outer layer of circumferential lamellae Synthesize and secrete bone matrix Inside the dense bone, there are multiple osteons/Haversian system o Circumferential rings of bone that sit around the Haversian Canal o Long axis of the column = long axis of bone Versus Volksman Canal which runs perpendicular o Lacunae with osteocytes inside osteon Nutrients out of Haversian canal, into osteon, into canaliculi, into lacunae Underneath the periosteal membrane, there are more circumferential lamellae o Outer layer of irregular dense fibrous connective tissue that has fibroblasts and mesenchymal stem cells (that differentiate into osteoprogenitor cells and then to osteoblasts) o Inner layer of osteoblasts Sit on the outer layer of circumferential lamellae Synthesize and secrete bone matrix 29 Blood flow in dense bone Haversian Systems/Osteon Oriented parallel to the long axis of the bone Central haversian canal with concentric lamella of bone centered around it Osteocytes sit in lacunae within the rings of bone and are oriented around haversian canal o Attached to collagen fibers that are inside the lacunae o Long arms that travel down canaliculi to attach to/communicate with other cells Dense Bone Structure Appositional bone deposition by osteoblasts of periosteum creates circunfrential lamella (3-4 layers of bone) Thousands of osteons packed together o Oriented around a Haversian Canal and parallel to long axis of bone o Single osteon consists of concentric lamella of bone all oriented around a central haversian canal o Haversian systems are constantly turning over Osteoclasts synthesize and secrete HCl and enzymes to break down extracellular matrix and resorb bone Cells attached to collagen fibers are oriented parallel with the force of the bone (i.e. femur = up and down) Causes osteoclasts to digest bone in that orientation Appositional (Interstitial) Bone Growth Growth in width 30 Arranged in layers around the entire circumference of the diaphysis Expands outer circumference of bone Eventually remodeled into osteon by cutting and closing cones of remodeling functions Deposit bone/circumferential lamellae under periosteum (osteoprogenitors, osteoblasts), resorb bone under endosteum (osteoclasts) Generating lots of circumferential lamellae around bone Osteoblasts and osteoclasts have coordinated activity Circumferential lamellae remodeled into osteons overtime Appositional bone deposition = interstitial bone growth Periosteum = fibrous connective tissue Constant turnover of bone Calcium used by all cells in the body to signal Eclampsia: calcium levels drop, no contraction in muscles, results in death Endochondral Ossification Growth in length Hyaline cartilage of epiphyseal plate = metaphysis Pushes epiphysis away from diaphysis o Chondrocyte replication and production of cartilage components (hyaluronin, proteoglycans, collagen fibers) Chondrocytes hypertrophy (enlarge and die) Cartilage becomes vascularized o Blood cells into tissue to deliver inflammatory cells that clean out dead tissue o Blood vessels deliver mesenchymal stem cells to cartilage matrix that turns into osteoprogenitor cells osteoblasts o Osteoblasts synthesize new bone components to replace cartilage components 31 Articular cartilage not on picture (above epiphyseal plate) Zones of cartilage: o Reserve zone of chondrocytes o Chondrocytes proliferate (isogenous groups) Cartilage matrix formed, lacunae present Nutrients delivered through compression/release of cartilage (sponge analogy) o Chondrocytes hypertrophy The more the matrix, the harder it is for the nutrients to diffuse to cells Cell death o Calcification Blood vessels grow into dying cartilage in attempt to repair it Vascularized cartilage turns to bone Bone vessels contain mesenchymal stem cells Androgens = testosterone, slow the process down Trabeculae: dying cartilage that has bone being deposited around it Osteoprogenitor Cells Mitotic cell Generates progency cells From mesenchymal stem cell Found throughout bone periosteum, endosteum, Volksman and Haversian canals Osteoblasts Early progeny of osteoprogenitor cell Synthesizees and deposits extrcellular components of bone (hyaluronin, collagen, proteoglycans, hydroxyapatite crystals) 32 o Hydroxyapatite crystals = calcium and phosphorous (CaPO4) Found in periosteum, endosteum, and closing cone of remodeling structures Osteocytes Mature osteoblast – develops from osteoblasts that encase themselves in extracellular bone components Exists in lacuna Connected to other osteoprogenitor cell series by long cytoplasmic arms that adhere to arms of other osteocytes/osteoblasts o Cytoplasmic arms exist in canaliculi channels extending from lacuna to lacuna Endogenous cell of bone – found throughout dense and cancellous bone Retains ability to synthesize as well as re-absorb extracellular bone components o Involved in calcium homeostasis and maintaining bone integrity Osteoclasts One cell type from myeloid (white blood cell) lineage Osteoclast is multinucleated cell formed by fusion of several cells together Osteoclast o Monocytic series of myeloid lineage (white blood cells) Location = endosteum and cutting cone of remodeling structures Function = re-absorption of extracellular bone components Enzymatic digestion of collagen fibers, hyaluronan, proteoglycans Synthesize and secrete proteases to digest components Acidic solubilization of hydroxyapitate crystals + Osteoclast synthesize and secrete H 33 Osteocalcin, Osteoectin o Calcium-binding proteins o Synthesized by osteocyte or osteoblast o Unique to bone extracellular matrix o Forms nucleus of which hydroxyapatite crystals precipitate out onto Bone Remodeling Location = anywhere in dense and cancellous bone Process: o Osteoclasts absorb bone matrix 34 Osteoclasts penetrate the bone (hot marble in butter) and align themselves along the force of the bone (most commonly a vertical force) Enzymatic digestion of organic components and acidic solubilization of hydroxyapitate crystals o New vascularization of hole from cutting cone Mesenchymal stem cells dragged in with new blood vessel that sits inside new Haversian canal Osteoprogenitor cells and osteoblasts formed o New bone formation Osteoblasts deposit bone matrix inside Haversian canal New concentric lamellae of bone formed around central canal of Haversian system In the closing cone End result = new Haversian system Anthrology: Joints Tissues of Joint Capsules 2 layers o Outer layer: irregular dense fibrous CT o Synovial membrane: basement membrane with single cell layer of cuboidal epithelium Synthesizes/secretes hyaluronan, amino acids, sugars, minerals, vitamins into joint space for chondrocyte metabolism Collateral ligaments o Localized “strip” of dense fibrous CT buried within irregular dense fibrous CT of joint capsule Extends across two bones articulating with one another Usually anatomic arrangement is one medial and one lateral collateral ligament Fibrocartilage meniscus o A disc shaped plate of fibrocartilage o Both surfaces are usually a convex shape o Positioned in the articular space and articulates with the articular cartilage of two bones that make a joint o Purpose is to make two non-congruent articular surfaces extremely congruent and stabilize joint movement into one plane o Examples: menesci of the femoral-tibial joint or the intervertebral meniscus located between the articular surfaces of two vertebral bodies Cruciate ligaments o Usually two ligaments positioned within the joint space and extending from the articular surface of one bone to the articular 35 surface of the second bone-prevent cranial-caudal sliding of one articular surface with another articular surface 36 Muscle Tissues Muscle belly: grossly visible muscle, consists of billions of myofibers Muscle fascicle: grossly visible thread of muscle belly Myofiber: = individual muscle cell, = muscle fiber, bag that holds a clump of angel hair pasta, multinucleated, nuclei located immediately underneath the cell membrane, extends from the origin to the insertion 37 Myofibril: contractile substance that fills the myofiber, looks like a clump of angel hair pasta, extends from the origin to the insertion Myofilament: protein structure that makes up the contractile element of a muscle cell, one strand of angel hair pasta 2 types – myosin and actin Myofilaments (myosin and actin) makes a myofibril. Myofibrils form a myofiber. Myofibers forms a muscle fascicle. Muscle fascicles form the muscle belly 3 Types of Muscle Cardiac (striated) Smooth Skeletal (striated) Fibrous Connective Tissue of Muscle Epimysium: outer layer, rind of a grapefruit, loose and irregular dense CT Perimysium: surrounds fascicles (divide muscle into pieces), spokes of CT that poke into fascicles, irregular dense CT Endomysium: subunit of perimysium, collagen fibers attach to myofiber plasma membrane All collagen fibers distributed thoughout these three layers are collected at the end of the muscle to form a tendon Motor Unit 38 Neuron attaches to every myofiber If the attachment is destroyed, there is a loss of innervation to those myofibers and they die (loss of muscle mass) Motor units = one efferent somatic motor neuron and all the muscle fibers innervated by the neuron. o Can have 1 neuron per 2-3 myofibers – fine muscle control like that needed in the iris o Can have 1 neuron per 1000 myofibers – course muscle control like that needed in quadriceps to counteract gravity Sarcolemma: plasma membrane of a myofiber Sarcoplasm: cytoplasm of a myofiber Sarcomere: functional contractile unit of a muscle fiber SKELETAL MUSCLE!! 39 Sarcomere = contractile unit, arranged side by side down a myofibril o During contraction, sarcomeres shorten by drawing the two ends towards the middle Myofibril Arrangement (1 sarcomere depicted) 40 Myosin o Pink o Heavy chains o Appearance of a golf club at the molecular level with the heads at the ends and the handles tied together in the middle o Heads can flex and are energy dependent o Heads bind to sites on the actin filaments Actin o Green o Protein that has a globular structure o Interdigitating the myosin heavy chains o Alpha-actinin Holds actin together within their chains Anchors actin at the end of the sarcomere 41 Also joins sarcomeres together by attaching the ends of actins together Ends are “welded” together down the length of the myofibril o Tropomyosin: protein wrapped around actin filaments Troponin C: protein attached to tropomyosin Rigid arrangement of myofilaments within the myofibril o Gives the myofibril the pattern of cross-striations Z-band: end of a sarcomere, where actin filaments from two sarcomeres are welded together end-to-end A-band: fill length of myosin heavy chains (golf club head to golf club head) M- band: where myosin is covalently linked together H-band: two free ends of actin filament across myosin filament A-band: length of myosin I-band: end of one myosin filament to the end of the end of another myosin filament (includes Z band) Contraction Actin moves inward Z-bands brought closer together thanks to the actin H and I band shortens M and A band not affected Steps o 0 In the resting state, the tropomyosin is positioned on the actin filament to cover all the binding sites of the myosin heads Myosin cannot yet bind to actin o 1 Calcium levels rise in the cell o 2 Calcium binds to troponin C o 3 Structure of troponin C changes so drastically that the tropomyosin changes its location just slightly along the actin filament o 4 Myosin binding sites on the actin filament are exposed o 5 Myosin attaches to the actin chain o 6 Myosin heads flex, ratcheting the actin down the myosin towards the M-band o 7 Once energy is released, the myosin heads relax, let go of the actin filaments, and everything returns to its resting state 42 Plasmalemma T-tubules – channels through the myofiber Sarcolemma Myofiber Myofilaments Smooth muscle in ring shapes 43
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