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Block 5 ellen > Muscle physiology L13 > Flashcards

Muscle physiology L13 Flashcards

(73 cards)

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1
Q

What are muscle stem cells called

A

satellite cells

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2
Q

When do satellite cells become activated

A

growth and muscle repair

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3
Q

Outer layer of muscle fascia

A

epimysium

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4
Q

What does the perimysium surround

A

the muscle fascicle

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5
Q

what surrounds the muscle fiber

A

endomysium

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6
Q

What are individual muscle fibres called

A

myofibrils

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7
Q

What surrounds myofibrils

A

sarcolemma membrane

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8
Q

A sacromere is between

A

2 Z lines

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9
Q

Difference between cardiac and skeletal muscle

A

cardiac= branched

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10
Q

What causes striations

A

overlap of actin and myosin

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11
Q

thick filament=

A

myosin

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12
Q

thin filament=

A

actin

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13
Q

2 proteins associated with actin

A

tropomyosin

troponin complex

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14
Q

troponin complex is made of

A

TnT
TnC
Tnl

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15
Q

What decreases during muscle contraction

A

distance between the Z lines

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16
Q

Calcium binds to

A

troponin C

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17
Q

What moves out of the myosin binding site

A

TnI

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18
Q

What does the myosin head act as

A

ATPase (hydrolysing ATP)

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19
Q

What is optimal resting length for a muscle

A

full overlap between thick and thin filaments

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20
Q

Decreased muscle length

A

Actin poking through M line; myosin bumping into Z disc

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21
Q

increased muscle length

A

decreased overlap

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22
Q

No overlap of myosin and actin?

A

Muscles are not naturally stretched to this point

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23
Q

Rigor mortis begins

A

3-4 hours after death

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24
Q

HOW LONG DOES RIGOR MORTIS LAST FOR

A

24 hours

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25
Why does rigor mortis happen
Ca2+ diffuses out of SR and allows myosin to bind to actin, no ATP to detach cross bridges
26
What stops rigor mortis
proteolytic lysosomal enzymes decompose cells
27
3 things neuromuscular junction consists of
axonal terminal of a somatic motor neuron synaptic cleft Motor end plate
28
Why are muscle membranes highly folded
increase surface area
29
Neurotransmitters in skeletal muscle=
acetyl choline
30
Receptors in skeletal muscle=
nicotinic cholinergic receptors
31
In a neuromuscular junction what channels are opened on the motor end plate
Na/K+ channels (more sodium goes in )
32
Choline --->
retaken up by the nerve terminal
33
Acetate--->
goes into kreb cycle
34
What does curare do
blocks nicotinic acetylcholine receptors
35
What does botulinum toxin do
stops the release of the vesicles
36
Resting membrane potential of skeletal muscle=
-90mV
37
Threshold of skeletal muscle=
-50mV
38
What does suxamethonium do
depolarises the muscle membrane preventing end plate potentials
39
In skeletal muscle what is either side of the transverse tubule
terminal cisternae
40
A triad in skeletal muscle=
2 terminal cisternae either side of transverse tubule
41
What happens within the triad
excitation-contraction coupling
42
In cardiac muscle what is instead of a triad
a diad
43
why are L-type Ca2+ channels opened
membrane depolarisation (DHP binds to the channel)
44
What binds to the Ca2+ release channels
Ryanodine
45
What causes the release of Ca2+ from the SR
mechanical coupling between the L-type Ca2+ and the Ca2+ release channel
46
In skeletal muscle what isn't released compared with cardiac
extracellular calcium
47
What pumps calcium back into the Sarcoplasmic reticulum
Calcium ATPase
48
What is a muscle twitch
muscle contraction in response to a stimulus that causes action potential in one or more muscle fibres
49
Three phases of muscle twitch
Lag phase Contraction phase Relaxation phases
50
What is temporal summation
before the muscle has relaxed from contraction it is stimulated again Increase in contraction strength
51
what is unfused tetanus
stimulations very close together only a small amount of relaxation
52
What is fused tetanus
muscle stimulated so much no time for relaxation
53
What is a motor unit
Motor nerve + all muscle fibres it innervates
54
innervation ratio=
the number of muscle fibres innervated by a nerve
55
In a small stimulation what motor neurons are recruited first
small motor neurons innervating small muscle fibres
56
In a large stimulus what motor neurons are recruited
larger motor neurons and there motor units
57
isometric muscle contraction=
no change in muscle length
58
isotonic muscle contraction=
length shortens
59
As the force of a load increases contraction changes from
isotonic--> isometeric
60
3 types of skeletal muscle
``` slow-twitch (type 1) Fast-twitch (type 2b) Fast twitch (type 2a) ```
61
Facts about slow twitch type 1 (4)
always oxidative resistant to fatigue most myoglobin (red fibres) Good blood supply
62
Which fibres have the most myoglobin
slow twitch type 1
63
What do slow twitch fibres control
posture
64
Fast twitch type 2b (3) facts
white fibres poorer blood supply susceptible to fatigue
65
Fast- twitch 2a facts
intermediate fibres oxidative intermediate myoglobin (pink-red) Resistant to fatigue
66
2 types of muscle fibres resistant to fatigue
slow twitch | fast twitch 2a
67
3 sources of ATP in muscles
creatine anaerobic respiration aerobic respiration
68
Myopathy=
any muscle disease
69
Myositis =
muscle inflammatory
70
Muscular dystrophy is
weakening skeletal muscle over time (inherited)
71
Myasthenia=
increasing weakness on exercise
72
Myotonia=
failure of relaxation
73
Channalopathies=
abnormal Na+, K+, CL- channels

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