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25 Cards in this Set
- Front
- Back
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functions of muscle contraction
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movement
stabilization movement of substances thru body generating heat to maintain body temp |
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function of synergistic muscles
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assist agonist by stabilizing the origin bone or positioning the insertion bone during mvmt
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bones and muscles as levers
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most lever systems of body act to increase required force of muscle contraction (more than mg to lift m) = because shorter lever arm decreases body bulk and increases range of motion
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muscle contraction steps
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1. tropomysoin covers active site on actin (myosin head can't bind)
2. Ca2+ and troponin - pulls tropomyosin back, myosin can bind to actin 3. myosin expels P and ADP into low E position, bend and drag action = contraction 4. ATP attaches to myosin head = release from active site; tropomyosin covers 5. ATP splits; head cocked into high E |
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sarcomere parts
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sarcomere=smallest unit; many end to end = myofibril
thick filament- myosin thin filamen - actin sarcoplasmic reticulum covers myofibrils = filled with Ca2+ ions multinucleate sarcolemma wraps myofibrils together |
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muscle contraction steps
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AP at neuromuscular jn
Ach into cleft activates ion channels in sarcolemma = AP AP moves in via t-tubules ** uniform contraction! - transferrred to sarcoplasmic reticulum - permeable to Ca2+ ions at end of contraction, Ca2+ pumped back into SR |
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motor unit
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neuron and muscle fibers it innervates (2 -2000 fibers)
units are independent of each other force of contraction depends on # and size units and frequency of AP typically smaller recruited first, larger as needed = smoothhhh |
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Type I muscle fibers
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- slow oxidative
- red (myoglobin) - lots mito - slow ATP split = slow to fatigue = slow contraction velocity postural muscles |
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type II muscle fibers
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- fast oxidative
- red (myoglobin) - split ATP fast = contract rapidly = med. fatigue (upper legs) |
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type III muscle fibers
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- fast glycotic
- white (no myoglobin) - contract rapidly - lots of glycogen upper arm |
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excercise changes...
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- increse muscle fiber diameter
- increase # sarcomeres - increase # mitochondria - increase length of sarcomeres all is HYPERTROPHY (not hyperplasia = mitosis; lost ability, v rare does split) |
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cardiac vs skeletal muscle
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- both striated (sarcomeres!)
- cardiac is mononucleated - gap junctions at intercalated discs (vs t tubules in skeletal) - larger and more mito in cardiac - supported by a "net"; pulls in on itself (instead of bone) - involuntary - both grow by hypertrophy |
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smooth muscle
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- involuntary
- innervated by autonomic NS - mononucleated - thick, thin and intermediate filaments, attached to dense bodies spread thru cell - pulled together during contraction (shrink lengthwise) 2 types: single and multi unit also contract or relax in presence of hormones, changes in pH, O2, CO2, temp, ion concentrations |
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types of smooth muscle
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single-unit:
- visceral - most common - connected by gap junctions - spread AP thru large group of cells - eg small arteries and veins, stomach, uterus, urinary bladder Multi-unit: attached directly to neuron - can contract independently of other muscle fibers in the same location - eg large arteries, bronchioles, pili muscles of hair follecs, iris |
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bone cell types
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-osteoprogenitor/osteogenic
-osteoblasts (secrete collagen and inorganic comps upon which bone is formed; eventually enveloped and diff into osteocytes) - osteocytes (exchange nutrients and waste w blood) - osteoclasts (resorb bone matrix) |
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spongy bone vs compact
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red marrow (RBC production) vs yellow marrow (adipose)
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flat bones
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provide large areas for muscle attachment and organ protection (skull, sternum, ribs...)
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bone and mineral homeostasis
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free [Ca2+] in blood important physiologically (most Ca is bound up by proteins and phosphates etc)
too much free Ca = hypo-excitable membranes; too little = cramps, convulsions most stored in bone matrix as HYDROXYAPATITE - lie along collagen fibers (tensile) to give compressive strength Calcium salts CaHPO4 buffer plasma levels |
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bone modelling process
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osteoclasts burrow into compact bone = Haversian central canals
osteoblasts follow laying down new matrix = lamellae trapped osteocytes exchange via canaliculi blood and lymph thru haversian canals and volkmanns canals (connectors) = HAVERSIAN SYSTEM/ OSTEON |
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Cartilage
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composed primarily of collagen = tensile strength
no blood vessels or nerves except outside membrane (perichondrium) hyaline most common - friction and shock decrease in joints |
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types of joints
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fibrous - little/no mvmt, held together w fibrous tissue (skull, teeth)
cartilaginous - little/no mvmt, held together with cartilage - ribs and sternum synovial - not bound, seperated by synovial fluid (lub and nutrients) |
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Functions of skin
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themoregulation (sweat, radiation, vasodilation, hair)
protection environ sensory input excretion (water and salts; diffusion independent of sweating) immunity blood reservoir (10% in dermis) vit D synthesis |
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integumentary system
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skin, hair, nails, glands, some nerve endings
hair = column keratinized cells + sebaceous oil gland + arrector pili muscles nails = keratinized as well sudoriferous sweat glands ceruminous glands (ear wax) |
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epidermis
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avascular
1. 90% keratinocytes (waterproof) 2. melanocytes = transfer pigment to kerts 3. langerhans - interact w helper t cells 4. merkel cells - attach to sensory neurons, touch 5 strata; deepest = Merkel and stem cells |
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dermis
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connective tissue derived from mesodermal cells
embedded w blood vessels, nerves, glands, hair follicles collagen, elastic fibers = strength, extensibility, elasticity below = subcutaneous layer = hypodermis - fat |
