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90 Cards in this Set
- Front
- Back
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Motion results from this........
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alternating contraction (shortening) and relaxation of muscles.
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What is myology?
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the scientific study of muscles.
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What are the 3 types of muscle tissue?
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Skeletal, Cardiac, and Smooth
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Skeletal Muscle
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(1) is voluntary (2) attaches to bone, skin or fascia (3) long, striated, cylindrical fibers (4) striated with light & dark bands (5) multinucleated.
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Cardiac Muscle
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(1) involuntary (2) intercalated disks connect fibers together (3) branched fibers are striated (4) autorhythmic (built in pace maker)
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Smooth Muscle
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(1) involuntary(2) attached to hair follicles in skin, walls of hollow organs, blood vessels & GI Tract (3) not striated, but spindle shaped in appearance
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Functions of Muscle Tissue
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(1) produce body movements (2) stabilize body positions (3) regulate organ volumes (4) move substances in the body (5) produce heat
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Smooth Muscle Tissue Functions
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(1) regulate organ volumes via the sphincters (2) move substances in the body.
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Sphincters
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smooth muscle located at entrances and exits of organs which open and close to let materials in and out.
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Smooth muscles involuntarily move these substances in the body.......
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blood, lymph, urine, air, food and fluids (sperm)
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Properties of Muscle Tissue
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(1) Excitability (2) Conductivity (3) Contractility (4) Extensibility (5) Elasticity
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Excitability
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ability to respond to chemicals released from nerve cells -causes them to contract.
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Conductivity
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ability to propagate electrical signals (nerve impulse) over membrane - starts contraction.
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Contractility
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ability to shorten and generate force.
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Extensibility
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ability to stretch.
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Elasticity
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ability to return to original shape after being stretched.
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Voluntary
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aware
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Involuntary
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unaware
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Skeletal Muscle
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Each one is a separate organ composed of cells, called fibers.
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Epimysium
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surrounds whole muscle.
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Perimysium
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surrounds bundles (fascicles) of 10-100 muscle cells.
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Endomysium
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separates individual muscle cells.
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All these (peri, endo, epi...mysium) connective tissue layers extend beyond the muscle belley to form what?
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the tendon that connects the muscle to a bone.
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These are extensions of connective tissue beyond muscle cells that attach muscle to bone or another muscle?
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Tendons and aponeuroses.
Singular: tendon/aponeurosis |
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Tendon
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a cord of dense connective tissu that attaches a muscle to the periosteum of a bone.
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Aponeurosis
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a tendon that extends as a broad, flat layer.
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Each Skeletal Muscle......
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is supplied by a motor neuron (nerve), artery,and two veins.
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Where do motor neurons communicate with muscle cells?
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Neuromuscular Junction
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Each Muscle Cell...........
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is supplied by one motor neuron terminal branch and is in contact with one or two capillaries.
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Where are nerve fibers and capillaries found?
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in the endomysium between individual cells.
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Myofibrils
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are the contracting elements of muscles. The threads of muscle fibers.
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Sarcolema
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covers groups of myofibrils; the muscle cell plasma membrane.
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Sarcoplasm
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is the muscle cell cytoplasm which contains a large amount of glycogen and myoglobin.
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Glycogen
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energy production, necessary for making ATP for energy. It is storage form of gluclose strung together. Found in sarcoplasm.
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Myoglobin
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oxygen storage. Found in sarcoplasm.
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Sarcoplasmic Reticulum
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system of tubular sacs similar to smooth ER in non muscle cells. Stores Ca+2 in relaxed muscle.
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What triggers a contraction?
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Release of Ca+2 from sarcoplasmic reticulum.
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T-tubules
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(Transverse) tubules are invaginations of the sarcolemma into the center of the cell.
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What is the T-tubule filled with and what is it's function?
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Extracellular fluid. Carry muscle action potentials down a cell.
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Mitochondria
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energy factories which lie in rows throughout the cell near the muscle proteins that use ATP during contraction.
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What two animals have a lot of mitochondria throughout their muscle cells?
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Hummingbirds/Rattlesnakes
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Sarco
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muscle prefix
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What 3 groups of protein make up Myofibrils ?
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Contractile proteins, regulatory proteins, structural proteins.
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Contractile proteins
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1/3 proteins in myofibrils which contain myosin and actin.
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Regulatory proteins
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1/3 proteins in myofibrils which contain troponin and tropomyosin that turn contraction on and off.
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Structural proteins
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1/3 proteins in myofibrils which contain titin, myomesin, nebulin, dystrophin which provide proper alignment, elasticity and extensibility.
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Sarcomeres
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myosin and actin filaments which overlap each other in a pattern that creates striations. The filaments are arranged in these compartments, separated by z discs.
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Myosin
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thick filament, contractile protein, each one resembles 2 golf clubs twisted together which extend toward the actin.
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Actin
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thin filament, contractile protein
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What are thin filaments made of?
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Actin, troponin & tropomyosin
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How does the muscle contract?
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Actin & myosin in sarcomere slide over each other, the troponin turns over and uncovers the sticky spots so myosin can grab and pull. Actin filaments slide inward. Z discs come toward each other and the muscle fiber shortens.
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What are the thin filaments held in place by?
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Z-lines
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Z-line to z-line =
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one sarcomere
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What are the functions of structural proteins?
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keep the thick and thin filaments in the proper alignment, give myofibril elasticity and extensibility, and link te myofibrils to the sarcolemma and extracellular matrix.
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What are structural proteins?
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titin, myomesin, nebulin, dystrophin
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What is the function of titin (structural protein)?
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anchors thick filament to the M line and the Z disc and helps muscle recover from being stretched.
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Nebulin
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inelastic protein that wraps around thin filaments to keep them aligned.
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Dystrophin
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links thin filaments to sarcolemma.
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The M- Line
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(myomesin) connects adjacent thick filaments to each other (middle)
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What are the 4 steps to contraction cycle?
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ATP hydroloysis releases energy that powers mysosin heads, myosin attaches to actin to form crossbridges, power stroke (myosin head pulls actin, myosin detaches from actin. Cycle keeps repeating as log as there is ATP available & there is a high Ca+2 level near the filaments - until sarcomere is completely contracted.
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What must be available for muscle contraction due to binding with troponin?
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Ca+2 (calcium)
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What must be available for muscle contraction (energy)? Why?
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ATP, because it energizes the myosin power stroke and powers the myosin to break away from the actin with the power stroke is finished.
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Neuromuscular Junction
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the end of an axon communicates with a muscle fiber at the muscle's motor end plate region, but they don't touch.
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Synaptic cleft
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gab at the end of an axon of muscle fiber
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How many ACh receptors are on the motor end plate membrane on muscle fiber?
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30 million
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What reaches the axon end bulb and causes a release of ACh from synaptic vesicles?
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Nerve impulse
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What binds to receptors on muscle motor end plate, which opens the gated ion channels so that Na+ can rush into the muscle cell?
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ACh
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What causes the relaxation of the muscle cell?
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AChE - acetylcholinesterase (enzyme) breaks down ACh within the synaptic cleft, muscle action potential ceases, Ca+2 channels close, active transport pumps Ca+2 back into storage in sarcoplasmic reticulum, tropomyosin-troponin complex recovers binding site on the actin, muscle fibril relaxes.
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Botulinum Toxins
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block the release of neurotransmitter at the NMJ so muscle contraction cannot occur. Death occurs from paralysis of diaphram.
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Curare
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plant poison used to poison arrow tips, causes muscle paralysis by blocking the ACh receptors. Used to relax muscles during surgery.
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Neostigmine
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blocks removal of ACh from receptors so it strengthens weak nerve-to-muscle impulses. Used as antidote for curare after surgery.
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What are three sources of ATP production within the muscle?
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creating phosphate, anaerobic cellular respiration, aerobic cellular respiration
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Anaerobic
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without oxygen
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aerobic
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with oxygen
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What makes ATP?
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mitochondria
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Muscles use this very quickly when active.
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ATP
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Cellular respiration
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a chemical process in which gluclose molecules from the food we ear are completely broken apart. Breaking the chemical bonds in the gluclose molecule releases energy.
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Anaerobic respiration
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if no O2 is present in muscle, cellular respiration stops at glycolysis. Pyruvic acid is converted into lactic acid which diffused into the blood (causes sore muscles). Only 2 ATP's are produced.
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Aerobic respiration
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If O2 is available in muscle, pyruvic acid is completely broken down through the reset of the steps cellular respiration and 36 ATP's are generated.
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Creatine Phosphate
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is unique to muscle fibers and with ATP can power maximal muscle contraction for about 15 seconds. Used for short bursts of energy (100m dash)
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Myogram
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a record of muscle contraction.
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Parts of a Twitch Contraction
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Latent Period Ca+2 is released from SR, Contraction Period actin is being pulled over myosin, Relaxation Period active transport of Ca+2 back into SR, Refractory Period muscle cannot respond and has lost its excitability.
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The Motor Unit
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one motor neuron and all the skeletal muscle cells it stimulates. Powerstrip
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Muscle Tone
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Involuntary contraction of a small number of motor units, necessary for maintaining posture.
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Muscles are classified into these 3 types
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Slow Oxidative (slow twitch) (red), endurance. Fast Oxidative (red), sprinting. Fast Twitch Glycolytic (white) bursts of energy, tire quickly.
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Name the 2 classifications of smooth muscle tissue.
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Visceral (single unit) in walls of hollow viscea and small blood vessels (digestive tract) Multiunit (one neuron activates one muscle fiber) found in large arteries, large airways, arrector pili muscles, iris & ciliary body.
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Smooth Muscle (Microscopic) Anatomy
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1) Spindle shaped cells taper at ends 2) single oval, centrally located nucleus 3) lack t-tubules and lave little SR for Ca+2 storage 4) sarcoplasm contains both thick and thin filaments which are not organized into sarcomeres 5)contain intermediate filaments which are attched to dense bodies. 6) no t-tubules, so Ca+2 must flow in from outside of cell. Regulator protein is calmodulin, not troponin.
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Smoot Muscle Contraction
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thick & thin myofilaments form "net" over cell. Drawstring affect.
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Regeneration of Muscle
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skeletal muscle fibers cannot divide after 1st year, Some repair can be done.
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Age at which skeletal muscle starts to deteriorate?
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30
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