10. 4 - 10.7 Flashcards

1
Q

resting membrane potential for skeletal muscle

A

NEGATIVE 85 mV (-85 mV)

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2
Q

excitable membranes

A

permit rapid communication between different parts of a cell

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3
Q

types of excitable membranes

A

depolarization
hyperpolarization
repolarization

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4
Q

depolarization

A

membrane potential becomes less negative due to influx of sodium ions

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5
Q

hyperpolarization

A

the membrane potential becomes more negative due to outflow of potassium ions

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6
Q

repolarization

A

return to the resting membrane potential after depolorization

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7
Q

neuromuscualar junction (NMJ)

A

the synapse between a motor neuron and a skeletal muscle fiber

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8
Q

axon (synaptic) terminal

A

expanded end of the axons of the motor neuron

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9
Q

motor end plate

A

folded membrane of the skeletal muscle fiber at the NMJ

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10
Q

synaptic cleft

A

narrow space between the axon terminal and the motor end plate

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11
Q

neurotransmitter

A

chemical released from the axon terminal into the synaptic cleft

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12
Q

neurotransmitter at the NMJ is

A

acetylcholine (ACh)

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13
Q

excitation-contraction coupling

A

link between the generation of an action potential in the sarcolemma and the start of muscle contraction

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14
Q

steps of excitation-contraction coupling (5)

A
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15
Q

contraction cycle

A

series of molecular events that enable muscle contraction

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16
Q

contraction cycles involved the formation of

A

cross bridges: myosin heads bind to the active sites on actin

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17
Q

power stroke

A

the myosin head uses energy from ATP to pivot and pull on active towards the M line

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18
Q

steps that initiate a muscle contraction

A

-ACh released
-action potential reaches T tubule
-sarcoplasmic reticulum releases stored calcium ions
-active sites exposed and cross bridges form
- contraction cycle begins

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19
Q

steps that end a muscle contraction

A

-ACh is broken down
- SR reabsorbs calcium ions
-active sites covered and cross bridge formation ends
- contraction ends
- muscle relaxation occurs

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20
Q

rigor mortis

A

muscle stiffens after death resulting from a muscles being locked in a contracted position

21
Q

tension

A

pull force generated by the muscle when it contracts

22
Q

length tension relationship

A

tension produced by a muscle fiber relates to the length of the sarcomeres

23
Q

twitch

A

a single stimulus contraction relaxation sequence

23
Q

myogram

A

graph showing tension development in muscle fibers

24
phases of a twitch
latent period contraction phase relaxation phase
25
latent period
the time it takes from the stimulation to move across the sarcolemma and for the SR to release calcium ions
26
contraction phase
tension increases as the muscle fiber is forming cross bridges and the myosin heads do power strokes
27
relaxation phase
tension decreases as cytosolic calcium ion levels decrease, myosin binding sites on actin are covered by tropomyosin, and cross bridges detach
28
treppe
an increase in peak tension caused by repeated stimulations which happen after the end of each relaxation phase
29
wave summation
increasing tension due to successive stimuli that arrive before the relaxation phase has been completed
30
tetanus
maximum tension
31
incomplete tetanus
the muscle produces near maximum tension due to rapid cycles of contraction and very brief incomplete relaxation
32
complete tetanus
the muscle is in continuous contraction due to high stimulation frequency which eliminates the relaxation phase
33
motor unit
a motor neuron and all the muscle fibers it controls
34
fasciculation
involuntary muscle twitch which is caused by the synchronous contraction of one motor unit
35
recruitment
increase in muscle tension due to the increase of active motor units
36
motor unit summation
"relay" approach in which some motor units are contracting, and some are resting and recovering
37
muscle tone
the resting tension of a skeletal muscle
38
types of muscle contractions
isotonic and isometric
39
isotonic contractions
causes the skeletal muscle to change length
40
isotonic concentric contraction
muscle tension exceeds the load (resistance) and the muscle shortens
41
isotonic eccentric contraction
peak muscle tension is less than the load and the muscle elongates due to gravity or the contraction of another muscle
42
isometric contractions
the skeletal muscle develops tension, but does not change length
43
how does atp transfer energy
atp transfers energy (in the form of a phosphate) to create creatine phosphate (CP) - catalyzed by the enzyme creatine kinase
44
atp is generated by
glycolysis and aerobic metabolism
45
glycolysis
anaerobic metabolism that breaks down glucose to pyruvate in the cytosol
46
aerobic metabolism
oxygen dependent process in which mitochondria use organic substrates (ex: pyruvate) to produce atp
47
recovery period
the time required for muscles to return to pre-exertion conditions
48
oxygen debt/excess postexercise oxygen consumption
the amount of oxygen required to restore normal pre-exertion conditions