Term
| skeletal muscle action steps |
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Definition
1. a muscle shortens when it contracts
2. places tension on tendons connecting it to bone
3. moves the bone at a joint
4. that bone is attached at the muscle insertion
5. the muscle is attached to a bone that doesn't move at the muscle origin |
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Term
| flexor vs. extensor muscles |
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Definition
1. flexor muscles: decrease the angle btwn two bones at a joint
2. extensor muscles: increase the angle btwn two bones at a joint |
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Term
| skeletal muscle actions (8) |
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Definition
1. extensor
2. flexor
3. abductor
4. adductor
5. levator
6. depressor
7. rotator
8. sphincter |
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Term
| abductor vs. adductor muscles |
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Definition
1. abductor: moves limb away from midline of body
2. adductor: moves limb toward midline of body |
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Term
| levator vs. depressor muscles |
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Definition
1. levator: moves insertion upward
2. depressor: moves insertion downward |
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Term
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Definition
1. have plasma membranes called sarcolemma
2. are multinucleated
3. are striated |
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Term
| I bands vs. A bands (muscle fibers) |
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Definition
I bands: lIght bands
A bands: dArk bands |
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Term
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Definition
1. single motor neuron and all the muscle fibers it innervates
2. contraction strength comes from motor unit recruitment
3. muscle fibers contract at once |
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Term
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Definition
1. sarcomere: area from one Z line to the next
2. titin: protein that anchors in the thick filaments and allows elastic recoil |
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Term
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Definition
1. when muscle contracts, sarcomeres shorten
- A bands don't shorten
- I bands shorten, but thin filaments don't
- Thin filaments slide toward the H zone (center) |
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Term
| thick and thin myofilaments |
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Definition
thick: composed of protein MYOSIN
thin: composed of protein ACTIN
- have proteins called tropomyosin and troponin that prevent myosin binding at rest |
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Term
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Definition
1. sliding is produced by several cross bridges that form btwn myosin and actin
2. power stroke (myosin head yanks the actin)
3. ADP is released and a new ATP binds
4. myosin releases actin
5. ATP is split
6. myosin head straightens out and binds to actin further back |
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Term
| regulation of contraction |
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Definition
1. tropomyosin physically blocks cross bridges
2. troponin complex |
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Term
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Definition
troponin I - inhibits binding of myosin
troponin T - binds to tropomyosin
troponin C - binds to calcium |
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Term
| sarcoplasmic reticulum (SR) |
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Definition
1. modified endoplasmic reticulum that stores Ca2+ when muscle is at rest
2. Ca2+ diffuses out of calcium channels when muscle fiber is stimulated
3. Ca2+ is actively pumped back into the SR at the end of a contraction |
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Term
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Definition
| when a muscle quickly contracts and relaxes after a single shock or voltage |
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Term
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Definition
| when a second shock is applies immediately after the first, the second twitch partially piggybacks the first |
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Term
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Definition
1. increasing the frequency of electrical shocks decreases the relaxation time btwn twitches
2. complete tetanus: when NO relaxation at a specific frequency (plateau) |
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Term
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Definition
as the voltage is increased, the number of muscle fibers in vitro increases
(staircase effect) |
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Term
| isotonic vs. isometric contractions |
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Definition
Isotonic: muscle fibers shorten when the tension produced is JUST GREATER than the load.
Isometric: muscles can't shorten b/c the load is too great |
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Term
| concentric vs. eccentric contractions |
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Definition
Concentric: muscle fiber shortens when force is greater than the load
Eccentric: muscle may lengthen, despite contraction, if the load is too great (ripping, tearing, overextension of muscle) |
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Term
| muscle strength determined by (4) |
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Definition
1. number of fibers recruited to contract
2. frequency of stimulation
3. thickness of each muscle fiber
4. initial length of the fiber at rest |
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Term
| where do muscles get their energy? (3) |
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Definition
1. at rest/mild exercise: fatty acids
2. moderate exercise: gycogen stores
3. heavy exercise: blood glucose |
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Term
slow-twitch fibers
(type I) |
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Definition
1. type I
2. slower contraction speed
3. slow to fatigue
4. more mitochondria
5. also called SLOW OXIDATIVE FIBERS |
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Term
fast-twitch fibers
(type II) |
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Definition
1. faster contraction speed
2. fatigue fast
3. fewer mitochondria
4. also called WHITE FIBERS |
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Term
fast-twitch fibers
(type IIA) |
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Definition
1. fast-twitch, but with high oxidative capacity
2. also called FAST OXIDATIVE FIBERS |
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Term
| why does muscle fatique happen? (5) |
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Definition
1. lactic acid build up
2. increased PO4 concentration
3. lack of ATP
4. build up of ADP
5. fatigue of upper motor neurons |
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Term
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Definition
1. skeletal muscles have stem cells called satellite cells
- can fuse to damaged muscle cells and repair them or form new
- myostatin inhibits satellite cells |
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Term
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Definition
1. alpha: contracting
2. gamma: stretching
3. coactivation (stimulated by upper neurons too) |
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Term
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Definition
| 1. monitor tension on tendons |
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Term
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Definition
1. respond to muscle length
2. muscles requiring more control have more spindles
3. when muscles stretch, spindles stretch |
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Term
| cardiac and smooth muscle |
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Definition
1. involuntary
2. regulated by autonomic nervous system
3. contraction due to myosin/actin cross bridges stimulated by calcium, like skeletal muscles |
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Term
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Definition
1. striated
2. myosin and actin filaments from sarcomeres
3. contraction by sliding filaments
4. short, branched unlike skeletal muscles |
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Term
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Definition
1. in blood vessel walls, bronchioles, digestive organs, urinary and reproductive tracts
2. peristaltic waves
3. no sarcomeres
4. long actin filaments
5. some myosin filaments |
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