Exam 3 Study Guide (Complete notes and filled out review questions)
Exam 3 Study Guide (Complete notes and filled out review questions) CBIO 2200
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This 44 page Study Guide was uploaded by Bailey Dickinson on Thursday October 6, 2016. The Study Guide belongs to CBIO 2200 at 1 MDSS-SGSLM-Langley AFB Advanced Education in General Dentistry 12 Months taught by in Fall 2016. Since its upload, it has received 104 views. For similar materials see Anatomy and Physiology I in Cellular biology at 1 MDSS-SGSLM-Langley AFB Advanced Education in General Dentistry 12 Months.
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Epidermal would healing- scrape- no blood. Repair of the skin: Inflammation, organization/proliferation, and regeneration/fibrosis/maturation Deep wound healing- blood clot forms, dilation of the blood vessels (so white blood cells and fibroblasts can migrate to clean up debris and fight off infection) Maturation- skin is regenerated. More collagen is produced- stronger tissue (scar tissue) no hair follicles or sweat glands Granulation tissue- preliminary tissue Keloid scar- when too much connective tissue is made Why doesn’t epidermal wound healing result in scar formation? No collagen fibers in epidermal tissue- no scar. Skin replaces itself and functions as normal What are the functions of skin? Barrier, regulates temperature, receptor, blood reservoir, vitamin D synthesis, excretion of wastes Bone function • Support • Protection • Movement • RBC production in red marrow • Fat storage in yellow marrow • Mineral homeostasis (calcium) Osteons run parallel to the long part of the bone (perpendicular direction) Osteocytes are found in the lacuna Osteons are individual pieces of spaghetti- contribute to the overall strength of the bone Marrow is found in the medullary cavity Periosteum- fibrous membrane around the bone -ost root: has to do with bone Bone Tissue Characteristics • Bone is connective tissue -Few cells, much matrix • Matrix is collagen fibers • Calcium salts deposited in matrix If you soak a bone in lemon juice, the calcium leaches out and the collagen is left- more flexible If you bake a bone, it becomes brittle- destroys the collagen Collagen (compact) layeràspongy layeràcollagen layer Osteon- functional unit in compact bone. Run in the long access of the long bone Arrangement of collagen fibers within the osteon provides exceptional strength in multiple directions Osteogenic cells differentiate into different cells Osteoclasts- come from immune system cells They break down bone tissue. Ruffled border Osteoblasts- lay down the matrix Osteocytes- trapped in the matrix- mature Osteoclasts- comes from WBC- immune system cells. Destroys bone. More nuclei- more effective The periosteum also plays a role in developing new bone You’re looking at a bone. You see lamellae, but no osteons. Is this sample from the epiphysis or diaphysis? Epiphysis- because osteons are only in the compact bone (diaphysis) Intramembranous ossification- beginning with a sheet of fibrous connective tissue. Left with spongy bone tissue in the center- and compact bone tissue on either side • Dermal ossification • An ossification center appears in a fibrous connective tissue membrane. Bone matrix is secreted within the fibrous membrane. This creates flat bones. • Osteoblasts differentiate in a layer of fibrous connective tissue (typically flat bones) • Bones formed this way include the flat bones of the skull, mandible, and clavicle • We need to be able to describe this in one or two sentences Fibrodysplasia Ossificans Progressiva - related to genetics or trauma. Inappropriate ossification Endochondral ossification- everything inferior to skull except clavicle • Bones formed this way result from a hyaline cartilage “template” becoming ossified. Requires breakdown of hyaline cartilage prior to ossification. Formation begins at the primary ossification center. • Bones inferior to the base of the skull are formed this way Responsible for the growth in length of most long bones The cartilage has to die (and be replaced by a calcified matrix) before it can be replaced with bony tissue Avascular- means no blood vessels There’s an infiltration of a blood vessel into the calcified matrix and brings osteoblasts, which use the matrix to lay down bony tissue (primary ossification center) Some fibroblasts will infiltrate into the area in which things are dying and blood supply is brought to the center. The osteoblasts begin to lay down bone tissue. Color of bony tissue comes from perichondrium. Intramembranous Endochondral Starting tissue Fibrous connective tissue Hyaline cartilage membrane Description Fibroblasts differentiate Cells in the template die; into osteoblasts; matrix is primary ossification laid down; spongy bone is center becomes formed; compact bone is vascularized; secondary formed from the cells in ossification center the periosteum becomes vascularized; cartilage remains in the epiphyseal plate (chondrocytes in the cartilage got bigger and died in the middle of the cartilage) Types of bones formed Flat bones in skull; All bones inferior to skull mandible, clavicle other than clavicle (everything else) Be able to identify the structure of boney tissue and describe the differences between spongy and compact bone Bone growth In length- at the epiphyseal plate (closes after puberty)- very similar to endochondral ossification In width- beneath the periosteum Bone growth in length • Very similar to endochondral ossification • Cartilage grows first, then is replaced by bony tissue “Bone chases cartilage” As the epiphyses is pushed further away, the bone gets longer The epiphyseal plate is not as dense as the bone so it shows up lighter on the x-ray Accessory Navicular Syndrome- disruption or change in the development of the navicular bone “Bone chases cartilage” describe and defend this statement • Cartilage grows first, dies, then is replaced by bony tissue Bone growth in width: similar to intramembranous ossification • Osteoblasts in the periosteum secrete matrix • Matrix builds up into new lamellae Bone remodeling • Bone deposit- building new bone or depositing new bone tissue in existing areas • Bone resorption- breakdown and removal of bone tissue Bone remodeling occurs • In response to hormonal changes • In response to mechanical stress • Bone turnover is constant! (Constant process throughout your life time) Hormonal Regulation of Bone Growth • Growth hormone • Thyroid hormone • Calcitriol • Sex hormones -Estrogen -Testosterone • Parathyroid Hormone • Calcitonin Parathyroid Hormone and Calcitonin • Regulate Ca2+ in the plasma • Opposite effects Bone remodeling • Bone deposit- building new bone or depositing new bone tissue in existing areas • Bone reabsorption- breakdown and removal of bone tissue Bone remodeling occurs • In response to hormonal changes • In response to mechanical stress • Bone turnover is constant! (Constant process throughout your life time) Hormonal Regulation of Bone Growth • Growth hormone • Thyroid hormone • Calcitriol • Sex hormones -Estrogen -Testosterone • Parathyroid Hormone • Calcitonin [Pituitary dwarfs and giants] [Acromegaly- excess growth occurs after the epithelial plates have closed. Square jaw] Parathyroid Hormone and Calcitonin • Regulate Ca2+ in the plasma • Opposite effects The skeleton is a bank of calcium and phosphorus Parathyroid hormone (negative feedback loop) • Released from parathyroid glands (distinct from the thyroid gland) • Released in response to LOW plasma Ca2+ levels • Stimulates osteoclasts and osteoblasts Calcitonin (negative feedback loop) • Released from the parafollicular cells of the thyroid gland • Released in response to HIGH plasma levels of Ca2+ • Inhibits osteoclasts Osteoporosis- loss of spongy bone and then more subjective to compressions What do joints (articulations) do? • Give the skeleton mobility • Hold the skeleton together Functional Classification of Joints (what do they do?) • Synarthroses (syn = together) -Immovable • Amphiarthroses (amphi = from both sides) -Slightly movable • Diarthroses (dia = through or apart) -Movable Structural Classification of Joints (what are they made of?) • Fibrous • Cartilaginous • Synovial Examples of fibrous joints (short fibers) • Sutures -Skull (increased surface area of connection because of zig-zag) -Nearly immovable • Syndesmoses -Connected by a ligament (distal end of tibia and fibula) • Gomphoses (gomphi = nail or bolt) -Tooth in bony socket Examples of cartilaginous joints • Synchondrosis -Rigid cartilage “bridge” between 2 bones -Epiphyseal plate • Symphyses -Articular cartilage -Public symphysis -Intervertebral joints What kinds of movements do you expect between the vertebrae? Rotation, flexion, extension, lateral flexion; amphiarthrotic/cartilaginous joints Synarthrotic and amphiarthrotic joints are in the axial skeleton Synovial joints • Joint is surrounded by a fibrous capsule (thickening of the periosteum) • Articulating bones are separated in a fluid-filled cavity No true epithelium, carries nutrients to the cartilage, removes waste, shock absorber; the cartilage is hyaline-like Features of synovial joints Synovial cavity- space that contains synovial fluid Articular cartilage- hyaline-like, thin, slick Synovial fluid- thick and lubricating, similar to interstitial fluid Articular capsule- 2 layers, continuous with the periosteum Other accessory structures Reinforcing ligaments -Intra and extra-capsular Cartilage menisci (meniscus-es?) Fat pads Bursae -Fibrous sacs of fluid Tendon sheaths -Elongated bursae What kinds of movements do you expect at synovial joints? Gliding- sliding Angular- changing the angle between two bones Rotation- rotating about the axis of the bones “Special” movements associated with particular joints The type of joint depends on the bones in the area Plane joint- sliding or gliding; two flat surfaces; carpels in the wrist Hinge joint- cylinder surface with a half cylinder that fits around it; elbow; flexion and extension Pivot joint- one cylinder and one structure that surrounds it completely; rotation about the long axis of the joint Condyloid joint- oval surface and an oval shaped cup; movement in two directions but not in circles Saddle joint- looks like a rider sitting on a saddle; same movement as condyloid joint; no rotation Ball and socket joint- shoulder and hip; one articulating surface that’s round, and one spherical sup shaped; most possible movement; can decrease angle in every direction and can rotate What movements are associated with hinge joints? Flexion and extension When you do jumping jacks, what movements are associated with the lower limbs? Abduction and adduction; for jumping? Do you use flexion and extension too? Chewing involves what movements? Elevation and depressed Pointing the toes? Plantar flexion Moving the palm so it faces anteriorly involves what movements? Supination Special movements; Seen only at specific articulations Your patient is a 26 year old gymnast who is complaining about muscle weakness in her face and arms. “My jaw gets tired when I’m eating” and it’s getting harder for me to “spot” my students in the gym. Electromyographic studies of the muscles in her arms reveal progressive weakness in decreased tension that develops during repeated muscle contraction You notice that her eyelids are droopy and have a sleepy appearance Three types of muscle Skeletal • Striated muscle, voluntary muscle • Muscles of movement Cardiac • Heart Smooth • Involuntary • Hollow organs, vessels, respiratory passages Skeletal muscle ^^ striated, multiple nuclei Each muscle fiber is as long as the muscle itself Cardiac muscle ^^ intercalated disc; the cells respond to electrical signals at the same time; can also be multi nucleated; fibers tend to be branched Smooth muscle^^ organized in sheets; contracts in a squeeze Back to the patient: What type of muscle tissue appears to be the source of the problem? Skeletal muscle Why do you think electrical studies of her muscle were conducted? Voluntary muscles; brain and muscles are connected; muscles are receiving signals- might be having an disuse with that; to see if the muscles are responding to the signals; skeletal muscle is electrically active tissue Functions of muscle tissue • Movement • Maintain posture/stabilize joints • Storage and movement of substances -Entrances and exits “guarded” by muscle sphincters • Generates heat • Support soft tissue Properties of muscle tissue • Excitability/Irritability -Responds to stimulus with an electrical signal that produces contraction • Contractility -Shortens forcibly • Extensibility -Can be stretched or extended • Elasticity -Returns to resting length Skeletal muscle > fascicle > muscle fiber > myofibrils Tendons: dense regular connective tissue You’re more likely to break the bone than to pull the tendon off of the bone Epimysium- covers the muscle Perimysium- covers the fascicle Endomysium- superficial to cell membrane- covers the muscle fiber Sarcoplasmic reticulum- stores calcium t-tubules- extensions of sarcolemma Thick filaments are surrounded by thin filaments Sarcomere: z-disc to z-disc A band is dArk I band is lIght Thick filament Thin filament- troponin (binding site for calcium) and tropomyacin regulate an active site on the active molecule Sliding Filament Theory • Thick filaments (myosin) form crossbridges with thin filaments • Thick filaments propel the thin filaments toward the center of the sarcomere • Thin filaments slide past the thick filaments, toward the M-line Contraction cycle • Events that occur in the myofibril/sarcomere • Interaction between thick and thin filaments For the active site to become active, Ca has to bind to troponin Why are the ends of the A bands the darkest region of the sarcomere when viewed under the light microscope? The ends of the A band have both thin and thick filaments. Myosin molecules have binding sites for what molecules? ATP and actin The ATP binding to myosin makes myosin’s affinity for actin less Myosin hydrolyzes ATP to ADP and Pi. We could call myosin a protein phosphatase What would happen if ATP were depleted in the muscle fiber? The cells die. The crossbridges form and don’t detach. Rigor mortis. Eventually the cross bridges detach because the proteins in the cells break down. Can use to help determine the time of death. What prevents the filaments from sliding back to their original position each time a myosin head releases? The myosin heads can release at staggered times and attach to other actin. What happens to the features of the sarcomere when skeletal muscles contract? M line is in the same spot. H zone, and I band are smaller in width. Z disks are closer together. The whole thing is darker. The A band doesn’t change size because the A band is the length of the thick filaments What tells the myofibril to shorten? • Electrical impulse from a neuron (a nerve cell in the central nervous system) • The neuron communicated with the muscle fiber chemically and the chemical signal is converted into an electrical signal • The signal in the muscle fiber causes Ca2+ release from the sarcoplasmic reticulum Action Potential • Electrical signal produced by ion movements • Nervous tissue and muscular tissue Sarcoplasmic reticulum is membrane bound and stores calcium Normally calcium is low in the cytoplasm. Need calcium to be increased in the cytosol so it can bind to troponin Sarcoplasmic reticulum and t-tubules = triad Calcium leaves the sarcoplasmic reticulum by facilitated diffusion because such a large amount of CA is on the inside as compared to the outside. Active transport pump puts the Calcium back in to the sarcoplasmic reticulum, or we wouldn’t be able to stop the contraction. As the length of the sarcomere decreases, tension increases (to a certain point) After that maximum tension point, as the length of the sarcomere is still decreasing, the tension decreases. Too much overlap of the myosin and actin; there’s nowhere left to go When the sarcomere is resting, it ahs more potential to develop tension (optimum length) When the sarcomere is too long, the myosin and actin cant attach because they aren’t overlapped Cardiac muscle is also striated so it has sarcomeres as well. We want this to happen in a forceful way so we can expel blood. Optimal length gives us a sufficient contraction. CBIO 2200 Review Questions- Lecture Exam 3 Bone Tissue/Joints/Muscle Tissue Chapter 6, “Bone Tissue and the Skeletal System.” We will be focusing on The Functions of the Skeletal System (pp. 216-220); Bone Structure (pp. 222-232); Bone Formation and Development (pp. 233-239); Calcium Homeostasis: Interactions of the Skeletal System and Other Organ Systems (pp. 247-248). Bone • Describe the features of osseous (bone) tissue o Hard, dense, connective tissue o Few cells, much matrix (collagen fibers) o Calcium salts are deposited in the matrix o Epiphysis- ends of long bones and covered in articular cartilage o Diaphysis- shaft of the bone (hollow region inside is called the medullary cavity and is filled with yellow marrow) o Softer, dense connective tissue is on the inside of bone (bone marrow) o Yellow marrow (adipose tissue), Red marrow fills spaces in spongy bone (blood cells) o The medullary cavity has a membranous lining called the endosteum (“inside the bone”) and the outer surface of the bone is called the periosteum (contains blood vessels, nerves, and lymphatic vessels) (covers the outer surface except where the epiphyses meet other bones to form joints) o Epiphyseal plate- a layer of articular cartilage in a growing bone • Compare and contrast compact bone with spongy bone. Give at least one other name for both types of bone Compact bone: [Dense] o Can withstand compressive forces o Found under the periosteum and in the diaphysis of long bones; the microscopic structural unit is called an osteon, or Haversian system o Each osteon is composed of concentric rings of calcified matrix called lamellae (singular: lamella) (light grey rings, not the grey blobs) o Running down the center of each osteon is the central canal, or Haversian canal, which contains blood vessels, nerves, and lymphatic vessels o These vessels and nerves branch off at right angles through a perforating canal, known as Volkmann’s canals, to extend the periosteum and endosteum o The osteocytes are located inside spaces called lacunae (singular: lacuna), found at the borders of adjacent lamellae (grey blobs in the circles) o Canaliculi connect with canaliculi of other lacunae and eventually with the central canal. This system allows nutrients to be transported to the osteocytes and wastes to be removed from them Spongy bone: [Cancellous] o Like compact bone, spongy bone contains osteocytes housed in lacunae, but the lacunae are not arranged in concentric circles o Greater surface area than compact bone o Prime target in diseases like osteoporosis; decreases in calcium to this bone can weaken it and cause it to break more easily o The lacunae and osteocytes are found in a lattice-like network of matrix spikes called trabeculae (singular- trabecular) o The trabecular aren’t random- arranged along lines of stress to provide strength to the bone o The spaces of the trabeculated network provide balance to the dense and heavy compact bone by making bones lighter so that muscles can move them more easily. o The spaces in some spongy bones contain red marrow, protected by the trabeculae, where hematopoiesis (the production of blood cells) occurs o Supports shifts in weight distribution • List and describe the 4 types of cells found in bone tissue o Osteoblasts: forms bone matrix; found in the growing parts of the bone, including the periosteum and the endosteum o Osteocytes: maintains bone tissue; maintain mineral concentration; entrapped in matrix; old osteoblasts; primary cell of mature bone; most common type of bone cell; in lacuna o Osteogenic: stem cell; develops into osteoblasts; deep layers of the periosteum and the marrow; undifferentiated with high mitotic activity; only bone cell that divides; creates osteoblasts which later turn into osteocytes o Osteoclasts: resorbs bone; bone surfaces and at sites of old, injured, or unneeded bone; originate from monocytes and macrophages (white blood cells), not osteogenic cells; break down old bone • Describe the composition of the matrix in bone tissue o The matrix is composed of collagen fibers and some cells that provide a surface for the inorganic salt crystals to adhere to. Calcium phosphate and calcium carbonate combine to create hydroxyapatite crystals, which give bones their hardness and strength; the collagen fibers give the bones flexibility. When you soak a bone in lemon juice, the Ca leaches out and the collagen remains- so it’s flexible. If you bake a bone, it destroys the collagen, so it becomes brittle • What are the functions of bone? (Give 3) o Supports the body o Facilitates movement o Protects internal organs o Produces blood cells o Stores and releases minerals and fat • How might damage to the thyroid gland affect calcium regulation in the body? o If the thyroid gland was damaged, it couldn’t release calcitonin which controls high calcium levels (stimulates calcium excretion), so there would be too much calcium absorbed and in the body and it wouldn’t be regulated. Blood calcium levels might become abnormally high. • What are two main hormones responsible for calcium homeostasis? Describe their actions. o Parathyroid hormone (PTH): Released from parathyroid glands (not thyroid gland); released in response to LOW plasma Ca 2+ levels; stimulates osteoclasts and osteoblasts Stimulates osteoclast proliferation and reabsorption of bone by osteoclasts; promotes reabsorption of calcium by kidney tubules; indirectly increases calcium absorption by small intestine Flow chart for Parathyroid hormone: Ca homeostasis is disruptedàCa is low in plasma (decreased)àStimulation of parathyroid cellsàParathyroid hormone is releasedàStimulates osteoclasts; increases # of osteoclasts; increases Ca reabsorption (kidney) and Ca absorption (gut) o Calcitonin: released from the parafollicular cells of the thyroid gland; released in response to HIGH plasma levels of Ca2+; inhibits osteoclasts; decreases Ca2+ reabsorption in the kidney; calcium can be released in urine Inhibits osteoclast activity and stimulates calcium uptake by bones Flow chart for Calcitonin: Ca homeostasis is disruptedàCa is HIGH in plasma (increased)àStimulation of parafollicular cells of the thyroidàCalcitonin is releasedàInhibits osteoclasts; decreases Ca2+ reabsorption in the kidney; calcium can be released in urineàincreased Ca deposit in boneàdecreased bone reabsorption These are both examples of negative feedback loops, even though one stimulates osteoclasts/osteoblasts and one inhibits osteoclasts • List two other hormones that play a role in bone growth and remodeling o Growth hormone- secreted by the pituitary gland; triggers chondrocyte proliferation in epiphyseal plates, resulting in the increasing length of long bones; increases calcium retention; enhances mineralization; stimulates osteoblast activity (improving density) o Thyroid hormone- secreted by the thyroid gland; promotes osteoblast activity (bone growth) and the synthesis of bone matrix o Sex hormones (Estrogen and Testosterone)- promote osteoblast activity; responsible for pubescent growth spurt; promote the conversion of the epiphyseal plate into the epiphyseal line, bringing an end to the longitudinal growth of bones o Calcitriol- active form of vitamin D; produced by the kidneys; stimulates the absorption of calcium and phosphate from the digestive tract • Describe the role of bone in calcium homeostasis o Calcium moves into bone as osteoblasts build new bone and out of bone as osteoclasts break down bone. The hormones parathyroid hormone (PTH) and calcitonin help regulate blood calcium levels. Calcitonin, secreted by the thyroid gland inhibits osteoclasts and stimulates osteoblasts, thus decreasing blood calcium levels. • Compare and contrast bone growth and bone remodeling o Bone growth: ossification; also uses osteoblasts to create bone; grows in length and width o Bone remodeling: process of bone renewal; keeps bones strong; osteoclasts are constantly breaking down bone; osteoblasts reform bone; overall, bone stays the same size • Give one characteristic of intramembranous ossification. List one way it differs from endochondral ossification o Intramembranous ossification: An ossification center appears in fibrous connective tissue (fibroblasts differentiate into osteoblasts) Bone matrix is secreted within the fibrous membrane. Spongy bone is formed. Compact bone is formed from the cells in the periosteum. This creates flat bones. (layer of compact, then spongy, then compact). Responsible for growth of WIDTH in most bones o Endochondral ossification: Bones formed this way require a hyaline cartilage “template” becoming ossified. Requires breakdown of template prior to ossification. The cartilage dies (because the chondrocytes got big and died) and then the primary ossification center is vascularized. The secondary ossification center is then vascularized. Osteoblasts are brought with the blood supply and create bone tissue. Formation begins at the primary ossification center. Bones inferior to the base of the skull (excluding clavicle) are formed this way. Responsible for growth in LENGTH of most bones. (On the diaphyseal side, the cartilage is ossified and the bone grows in length) Cartilage remains in the epiphyseal plate (until bone is done growing) Chapter 9, “Joints.” We will be focusing on Classification of Joints (pp. 358-360); Fibrous Joints (pp. 360- 363); Cartilaginous Joints (pp. 363-364); Synovial Joints (pp. 364-370); Types of Body Movements (pp. 373-378). Joints • Define “articulation” and give two functions o Articulation: where two bone surfaces come together; the surfaces tend to conform to one another (formed of fibrous connective tissue, or cartilage) o Functions: flexibility; permits movement at the joint (if a moveable joint); allows the two bones to perform a function together (either to move or to tightly connect the bones and prevent movement) • Describe the following movements: o Flexion: Decreasing the angle of a joint; bending the joint o Extension: Increasing the angle of a joint; straightening the joint o Hyperextension: o Abduction: Moving a limb away from the medial line of the body o Adduction: Moving a limb towards the medial line of the body o Circumduction: Conical movement of a limb extending form the joint at which the movement is controlled (360 degrees) o Elevation: Moving a body part in a superior direction o Depression: Moving a body part in an inferior direction o Protraction: Anterior movement (towards the front of the body) o Retraction: Posterior movement (towards the back of the body) o Pronation: Rotating the forearm so that the palm faces down if the forearm is flexed o Supination: Rotating the forearm so that the palm faces up if the forearm is flexed o Dorsiflexion: decreasing the angle of the ankle joint o Plantar flexion: increasing the angle of the ankle joint o Inversion: rotating the ankle so that the sole of the foot points towards the other food o Eversion: rotating the ankle so that the sole of the foot points away from the other food o Medial rotation: rotating a limb towards the medial line of the body o Lateral rotation: rotating a limb away from the medial line of the body • Define and give an example of each Synarthroses, amphiarthroses, and diarthrosis are based on function Fibrous, Cartilaginous, and Synovial are based on structure o Synarthroses: immovable or nearly immovable; strong union between articulating bones; important where bones provide protection for internal organs (sutures- fibrous joints between the bones of the skull that surround the brain) o Amphiarthroses: limited mobility; cartilaginous joint that unites the bodies of adjacent vertebrae; pubis symphysis o Diarthroses: freely movable; includes all synovial joints; most are found in the appendicular skeleton; uniaxial, biaxial, and multiaxial joints (movement in planes); shoulder, hip, elbow o Fibrous- contain fibrous connective tissue; immovable; sutures (skull); syndesmoses (connected by a ligament: radius and ulna); gomphoses (tooth in bony socket) o Cartilaginous- contain cartilage; very little movement; synchondrosis (rigid cartilage “bridge” between 2 bones; epiphyseal plate) symphyses (articular cartilage; pubic symphysis; intervertebral joints) o Synovial- have a space (synovial cavity filled with fluid) between the bones; allows for free movement; shoulder, hip, elbow • Structure of a synovial joint: articular cartilage (hyaline-like), articular capsule (2 layers), synovial membrane, synovial cavity (contains synovial fluid), synovial fluid (thick and lubricating) • Other structures: o Reinforcing ligaments: extrinsic (located outside of the articular capsule); intrinsic (fused to or incorporated into the wall of the articular capsule) o Intrinsic ligaments: can be intracapsular (inside the articular capsule) or extracapsular (fused to the wall of the articular cartilage) o Tendon: attaches muscle to bone “dynamic ligament” o Cartilage menisci: large and C shaped o Fat pads: cushion between bones o Articular disc: small and oval shaped; may unite the bones of the joint to each other; provides shock absorption; smooths movements between articulating bones o Bursae: thin connective tissue sac filled with lubricating liquid; reduces friction by separating the adjacent structures, preventing them from rubbing directly on each other. Submuscular bursa (between muscle and bone, or between adjacent muscles) Subtendinous bursa (between a tendon and a bone) • Describe the motion at each of the following. Give an example of a joint for each mechanical plan. o Plane joints: Gliding; allows movement between two plane surfaces (between carpals) o Hinge joints: One bone with a convex surface that fits into a concave depression on another bone; angular movement (elbow) o Pivot joints: One bone has a projection that fits into a ring-like ligament of another; rotational movement between two bones (head turning at neck) o Condyloid joints: A convex surface articulates with a concave surface; significant movement in two planes (knuckles) o Saddle joints: Two concave surfaces that articulate with one another; similar, but greater movement than a condyloid joint (between carpals and metacarpals) o Ball and socket joints: smooth hemispherical head fits within a cuplike depression; extensive movement, but less stable (dislocation) (shoulder) Chapter 10, “Muscle Tissue.” We will be focusing on Overview of Muscle Tissue (pp. 408-409); Skeletal Muscle (pp. 409-415); Muscle Fiber Contraction and Relaxation (pp. 415-423); Nervous System Control of Muscle Tension (pp. 424-429); Types of Muscle Fibers (p. 429). Muscle Tissue • Compare and contrast skeletal muscle, smooth muscle, and cardiac muscle with respect to structure, function, and special properties, and describe where each type of muscle is located o All three types of muscle have some properties in common: excitability (plasma membranes can change electrical states and send an electrical wave called an action potential along the entire length of the membrane), contractility; extensibility; elasticity o While the nervous system can influence the excitability of cardiac and smooth muscle to some degree, skeletal muscle completely depends on signaling from the nervous system to work properly o Both cardiac and smooth muscle can respond to other stimuli, such as hormones, and local stimuli o The muscles all begin the actual process of contracting when actin is pulled by myosin (this occurs in striated muscle [cardiac and skeletal] after specific binding sites on the actin have been exposed in response to the interaction between calcium and troponin o In smooth muscle, calcium activates enzymes which activate myosin heads o All muscles require ATP to continue the process of contracting, and they all relax when the Ca++ is removed and the actin binding sites are re-shielded o The actin and myosin proteins are arranged regularly in the cytoplasm of individual muscle cells (fibers) in skeletal and cardiac muscle, which creates striations o Skeletal muscles are multinucleated; cardiac muscle fibers have one to two nuclei and are physically and electrically connected to each other o In smooth muscle, the actin and myosin are not arranged in a regular fashion, it has a uniform, non-striated appearance Skeletal muscle: striated muscle; voluntary movement; muscles of movement; multiple nuclei; each muscle fiber is as long as the muscle itself; skeletal muscle>fascicle>muscle fiber>myofibril Smooth muscle: involuntary; hollow organs, vessels, respiratory passages; has less myosin and generates less tension than skeletal muscle Cardiac muscle: heart; involuntary; intercalated disc (allows the cells respond to electrical signals at the same time); fibers tend to be branched • Identify and describe the connective tissue coverings of muscle tissue o Fascia: dense sheet of irregular connective tissue that lines the body wall and limbs and supports and surrounds muscles and other organs; holds muscles with similar functions together; allows free movement of muscles; three layers of connective tissue extend from the fascia (epimysium, perimysium, endomysium) o Epimysium: dense, irregular connective tissue layer surrounding an entire muscle; separates the muscle from other tissues and organs in that area, allowing the muscle to move independently. o Perimysium- also a dense, irregular connective tissue, but surrounds groups of 10 to 100 or more muscle fibers, separating them into bundles called fascicles o Endomysium- penetrates the interior of each fascicle and separates individual muscle fibers from one another; mostly reticular fibers o Tendon: dense, irregular connective tissue that connects bone to muscle o Aponeurosis- broad, tendon-like sheet that connects a muscle with the parts is moves • Describe the microanatomy of skeletal muscle • Identify and describe the functions of the following o Muscle fiber: skeletal muscle cells; as long as the muscle itself; made up of myofibrils o Sarcolemma: plasma membrane of muscle fibers o Sarcoplasm: the cytoplasm of the muscle fiber o Sarcoplasmic reticulum: the specialized smooth endoplasmic reticulum that stores, releases, and retrieves calcium ions o t-tubules: deep invagination of the sarcolemma, which is the plasma membrane of skeletal muscle and cardiac muscle cells. These invaginations allow depolarization of the membrane to quickly penetrate to the interior of the cell o Myofibrils: cylindrical structures that extend along the complete length of each muscle cell; one of the slender threads of a muscle fiber; contains thick and thin filaments o Sarcomere: each packet of microfilaments and their regulatory proteins; from one Z disc to another in a myofibril o Thin and thick filaments: thick filaments are myosin and thin filaments are predominately actin, along with tropomyosin and troponin o Actin (thin filament) and myosin (thick filament): contractile microfilaments o Tropomyosin and troponin: regulatory proteins; troponin is associated with the thin filaments and can bind to the actin molecules; tropomyosin is a long, thin protein that extends between and binds to the troponin molecules o Triad: the arrangement of a t-tubule with the membranes of SR on either side. The triad surrounds the cylindrical structure called a myofibril, which contains actin and myosin • Identify the A band, the I band, the H zone, and the M line on a myofilament • Outline and describe the steps in the sliding filament theory o Overall: thin filaments are pulled and then slide past thick filaments within the fiber’s sarcomeres o The sliding can only occur when myosin-binding sites on the actin filaments are exposed by a series of steps that begins with Ca++ entry into the sarcoplasm o Tropomyosin is a protein that winds around the chains of the actin filament and covers the myosin-binding site to prevent actin from binding to myosin. o Tropomyosin binds to troponin to form a troponin-tropomyosin cmplex. This complex prevents the myosin “heads” from binding to the active sites on the actin microfilaments. o Troponin also has a binding site for Ca++ ions o To initiate muscle contraction, tropomyosin has to expose the myosin- binding site on an actin filament to allow cross-bridge formation between the actin and myosin microfilaments st o 1 step- Ca++ binds to troponin so that tropomyosin can move away from the binding sites on the actin strands (for the myosin heads) o The myosin heads then bind to the active sites and form cross bridges o The thin filaments are pulled by the myosin heads to slide past the thick filaments towards the center of the sarcomere. o Each head can only pull a very short distance before it has reached its limit and has to be “re-cocked” before it can pull again, a step that requires ATP o For thin filaments to continue to slide during muscle contraction, myosin heads must pull the actin at the binding sites, detach, re-cock, attach to more binding sites, pull, detach, etc. o This repeated movement is the cross-bridge cycle o The action of the myosin heads in the sarcomeres repetitively pulling on thin filaments also requires energy- ATP o Cross bridge formaton occurs when the myosin head attaches to the actin while ADP and Pi are still bound to myosin. Pi is the released, causing myosin to form a stronger attachment to the actin, after which the myosin head moves towards the M-line, pulling the actin with it. This is called the power-stroke (movement of the thin filament occurs) If no ATP, the myosin head will not detach from the actin. o One part of the myosin head attaches to the binding site on the actin, but the head has another binding site for ATP. o ATP binding causes the myosin head to detach from the actin. o After this occurs, ATP is converted to ADP and Pi by the ATPase activity of myosin. o The energy released during ATP hydrolysis changes the angle of the myosin head into a cocked position- ready for further movement o When the myosin head is cocked, it’s in a high-energy configuration. The energy is used as the myosin head moves through the power stroke. o At the end of the stroke, the head is in a low-energy position. ADP is released, but the cross bridge is still in place until another ATP attaches to myosin Muscle fibers contain contractile elements called myofibrils, which in turn are composed of functional units called sarcomeres. a. Describe the structure of a sarcomere. (Draw a picture, if you’d like….) Include in your description the orientation/ placement/ location of thick and thin filaments and identification / description of at least 2 other features. • Thick filaments: run the entire length of an A band • Thin filaments: run the length of the I band and partway into the A band • Z disc: coin-shaped sheet of proteins that anchors the thin filaments and connects myofibrils to one another • H zone: lighter mid region where filaments do not overlap • M line: line of protein myomesin that holds adjacent thick filaments together b. Describe the sliding filament mechanism of muscle contraction, beginning with a sarcomere at rest. You may want to break the mechanism into several stages but this is not necessary. Include the roles of ATP and calcium ion. Described in the answer to the previous question c. What would you expect to see if the sarcolemma suddenly became very permeable to Ca2+? What would happen to a resting skeletal muscle if the sarcolemma suddenly became very permeable to calcium ions? If the sarcolemma of a resting skeletal muscle suddenly became permeable to calcium ions, the cytosolic concentration of calcium ions would increase, and the muscle would contract. Also because of the amount of calcium ions in the cytosol must decrease for relaxation to occur, the increased permeability of the sarcolemma to calcium ions might prevent the muscle from relaxing completely. d. Compare and contrast the locations of the proteins in a sarcomere in contracted and relaxed sarcomeres. In contracted sarcomeres, the proteins are much more overlapped because the thick filaments have pulled the thin filaments more towards the M-line. The A band is the same size. The I band and H zone get smaller in width. Z discs are closer in contracted sarcomeres. We didn’t cover the below information. NOT ON TEST. An action potential is an electrical signal generated at excitable tissue, like muscle and nervous tissue. a. Describe a muscle cell membrane at rest. Include in your description the distribution of ions. b. Describe what happens during an action potential in a musc le cell. Include in your description the change in distribution of ions. c. Describe the events inside the muscle cell that lead to contraction. d. Describe the events inside the muscle cell that lead to relaxation. e. Distinguish between the organizati on of contractile elements in smooth muscle and skeletal muscle. How does contraction of smooth muscle differ from that in skeletal muscle? Botulinum toxin causes paralysis. It binds to the presynaptic sites at the neuromuscular junction and prevents the exocytotic release of acetylcholine from vesicles. a. Follow a molecule of ACh from the vesicle of a normal presynaptic terminal from the time of its release through its trigger of muscle contraction. b. What happens to ACh when muscle contraction is compl ete? c. Why do you think botulinum toxin producing paralysis? d. What might be expected to reverse the paralysis seen with botulinum toxin? On the following graph depicting the events of a muscle twitch, identify the three phases indicated. What events ar e occurring inside the muscle cell during each of these phases? What are isotonic contractions? Isometric contractions? Concentric and eccentric contractions? Give an example of each kind. What is a motor unit? What kinds of contractions do y ou see when motor units are large? When they are small? What are fast glycolytic fibers? Slow oxidative fibers? What are the characteristics of each? What pathways do each use to generate ATP?
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