9 Regulation of Skeletal Muscle Contraction Flashcards Preview

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Flashcards in 9 Regulation of Skeletal Muscle Contraction Deck (26):
1

each muscle depends on innervation by a

motor nerve

2

motor unit

one motor neuron plus all of the muscle fibers it innervates

3

the transfer of a signal from nerve to muscle takes place at the

neuromuscular junction
motor end plate
myoneuronal junction

(same thing)

4

presynaptic portion of NMJ contains vesicles with

acetylcholine

5

postsynaptic portion of NMJ contains

nicotinic acetylcholine receptors (ligand-gated)

6

order of events during neuromuscular transmission

1. action potential at axon terminal
2. Ca2+ enters axon terminal
3. Acetylcholine released across synaptic cleft, binds to postsynaptic membrane
4. Na+ and K+ ion channels open
5. Postsynaptic membrane becomes depolarized
6. Muscle AP triggered
7. Ach hydrolyzed
8. Choline is taken up, vesicles are refilled with Ach

7

cardiac cells are interconnected by

gap junctions

8

force of contraction in cardiac cells is dependent on

extracellular Ca2+ conc

9

calcium enters cardiac cells via

voltage-dependent slow calcium channels
or
L-type calcium channels

10

cardiac mm calcium comes from 2 sources

1/ extracellular Ca2+
2/ Ca2+ in SR
"calcium-induced calcium release"

11

_____ transfers a phosphate group to ADP to make it ATP

creatine phosphate

12

____ has ATPase activity

myosin

13

glycolysis

anaerobic
2 ATP net

14

citric acid cycle/ox phos

aerobic
36 ATP net

15

oxygen debt

extra oxygen consumption that occurs after exercise; stores are taken from hemoglobin and myoglobin; lactic acid is the largest contributor

16

3 sources of ATP production during muscle contraction

1/ creatine phosphate
2/ anaerobic glycolysis
3/ oxidative phosphorylation

17

isometric contraction

a contraction that generates force with no muscle shortening

18

isotonic contraction

a contraction that results in a shortening against a constant force

19

twitch

contraction and relaxation of a skeletal mm to a single stimulus (single AP)

20

total tension in a muscle depends on 2 things

1/ # of mm fibers contracting within a mm (recruitment)
2/ tension of each fiber (frequency of APs)

21

____ of _____ can influence the tension developed by each mm fiber

frequency of stimulation

22

summation

the force provided by the second stimulus (AP) adds to the force provided by the first (mm is re-stimulated before relaxation is complete)

23

tetanus

maximal sustained contraction; mm is stimulated so rapidly it does not have a opportunity to relax between stimuli

24

___ is achieved by increasing the excitatory synaptic input to the motor neuron

recruitment

25

red muscle fibers

AEROBIC (lots of myoglobin)
mitochondria abundant
fast twitch/slow twitch

26

white muscle fibers

ANAEROBIC
fast twitch only, fatigue quickly
fewer mitochondria