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Cell Physiology > Lectures 10-11 > Flashcards

Lectures 10-11 Flashcards

1
Q

What is flexion?

A

moves bones closer together

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2
Q

What is extension?

A

moves bones away from each other

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3
Q

How do skeletal muscle groups work in coordination?

A

one flexes limb or contracts | other = relaxes and extends

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4
Q

What is muscle fascicle?

A

bundle of muscle fibers

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5
Q

What is sarcolemma?

A

the covering of the muscle cell (cell membrane)

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6
Q

What is “sarco”?

A

prefix relating to muscle | flesh or muscular substance

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7
Q

What is “sarcoplasm”?

A

cytoplasm

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8
Q

What is sarcoplasmic reticulum?

A

modified endoplasmic reticulum in muscle fibers

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9
Q

What is the function of the sarcoplasmic reticulum?

A

store calcium (AKA: calcium stores)

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10
Q

What is the purpose of calcium in muscle cells?

A

signals for muscles to start contracting

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11
Q

What are the T-tubules?

A

continuation of the sarcolemma

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12
Q

What are the 4 functions of T-tubules?

A

brings APs into interior of muscle fiber | makes contact with individual units within muscle fiber | site of depolarization | responsible for Ca2+ release

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13
Q

Why is it important to increase the surface area within a muscle cell?

A

in order for all of the muscle fibers to exceed depolarization and be stimulated equally

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14
Q

What is a myofibril?

A

individual unit within muscle fiber

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15
Q

What is the functional unit of the muscle?

A

myofibril

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16
Q

What is the function of the myofibril?

A

contract/relax muscle when neuron sends a signal to the muscle fiber

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17
Q

What is the functional unit of the myofibril?

A

sarcomere

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18
Q

What components make up the sarcomere?

A

myosin | actin | M-line | Z-disk

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19
Q

How long is the sarcomere in length?

A

3 um

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20
Q

What is the M-line of the sarcomere?

A

mid-line

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21
Q

What is the Z-disk of the sarcomere?

A

ends of the sarcomere

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22
Q

What is the myosin of the sarcomere?

A

thick filaments

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23
Q

What are myosin heads of the thick filament?

A

hydrolyzes ATP and moves on actin to pull it closer (contraction) or further (relaxation)

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24
Q

What is actin?

A

thin filament

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25
Q

When will the myofibril slide back and forth?

A

when the calcium is released from the sarcoplasmic reticulum

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26
Q

Why is it important for the sarcomere to have a lot of surface area?

A

need calcium release to be efficiently and generously throughout the cell as each one of the myosin heads depends on the calcium in order to function

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27
Q

What is titin?

A

elastic protein provides elasticity | joins Z-disk to thick filaments

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28
Q

What is nebulin?

A

inelastic protein | keeps actin aligned

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29
Q

What is G-actin?

A

individual globular actin protein

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30
Q

What is F-actin?

A

chain of actin molecules | filamentous actin

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31
Q

Why do skeletal muscle cells have a lot of mitochondria?

A

use and need a lot of energy

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32
Q

What molecule binds to the myosin heads?

A

ATP

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33
Q

What does “myo” mean?

A

fiber in the muscle

34
Q

What are the parts of myosin?

A

2 tails intertwine | 2 protein chains per head (light chain and heavy chain)

35
Q

What is the function of the myosin head heavy chain?

A

motor domain | binds ATP to actin | hydrolyzes ATP

36
Q

What is the function of the myosin light chains?

A

regulatory and structural role

37
Q

What is tropomyosin?

A

wraps around F-actin | blocks binding site on actin = doesn’t allow myosin head to bind to actin

38
Q

What is troponin?

A

within the F-actin, where calcium binds to

39
Q

What are actin-myosin cross-bridges?

A

bridge between myosin binding to actin (basically myosin heads on actin)

40
Q

What is muscle tension?

A

force created by muscles –> can provide support on your body

41
Q

What does load mean?

A

weight or force that opposes contraction

42
Q

What does relaxation mean?

A

release of tension created by contraction = stops contraction

43
Q

What is the contraction-relaxation cycle?

A

switch between contraction and relaxation stages

44
Q

What is excitation-contraction coupling?

A

coupling of the excitation of the muscle cell from the action potential which will contract the muscle

45
Q

What is the relaxed state of actin-myosin?

A

myosin head cocked | tropomyosin partially blocks actin binding site

46
Q

What are the motor neurons triggered by in order to send info to muscles?

47
Q

What or where does the motor neuron innervate the muscle cell?

A

neuromuscular junction (NMJ)

48
Q

What are DHP channels?

A

calcium channel

49
Q

What is the DHP channel activated by?

A

depolarization wave on sarcolemma

50
Q

What is the DHP channel tethered to and what is its role?

A

RyR channel | open up RyR channels

51
Q

What is RyR channel?

A

ryanodine receptor channel located on sarcoplasmic reticulum

52
Q

What is ligand binding to a receptor dependant on?

A

concentration of the ligand

53
Q

What is the relationship between APs of the motor neuron and muscle fiber?

A

muscle cell depolarizes when the motor neuron repolarizes

54
Q

What is the delay due to in the timing of the excitation-contraction coupling of skeletal muscle contraction

A

diffusion of Ca2+ from sarcoplasmic reticulum to the actin-myosin complex | cross-bridges have to form = all take time

55
Q

What phase is the delay called?

A

latent phase

56
Q

When does the relaxation phase begin?

A

when calcium is being taken back up

57
Q

What is a phasic contraction? What is an example of one?

A

muscle = usually at rest | contracts only when it receives a stimulus | esophagus, peristalsis movement

58
Q

What is a tonic contraction? What is an example of one?

A

muscle = always contracting | relaxes only when it receives a stimulus | sphincters to pee and poo // vascular smooth muscles constantly in contraction or relaxation phases

59
Q

What are the 2 types of smooth muscles?

A

single-unit and multi-unit

60
Q

What is single-unit smooth muscle? What is an example of one?

A

connected via gap junctions channels inserted into membrane = electrical continuity | excited together |. ie: small intestine

61
Q

What is a multi-unit smooth muscle? What is an example of one?

A

individual connections, individual varicosities | excited individually | ie: eye

62
Q

Order the three kinds of muscles from fastest to slowest in contraction speed.

A

skeletal &raquo_space;> cardiac &raquo_space;> smooth

63
Q

What are the 2 differences in sarcomeres in smooth muscle cells from skeletal muscle cells?

A

no Z-disks, no lined-up sarcomeres | actin/myosin = aligned based on the shape of cell

64
Q

What are dense bodies?

A

connects actin and myosin in smooth muscle cells

65
Q

Why are there more myosin heads in smooth muscle cells than in skeletal muscle cells?

A

so that they can move more actin during cross-bridges

66
Q

What does a phosphatase enzyme do?

A

dephosphorylate

67
Q

What does autorhythmic mean?

A

does not need a signal to contract and function | can generate its own electrical activity

68
Q

How many twitches would a normal supply of ATP sustain?

69
Q

Which ATP-producing pathway is too slow to replenish ATP supply?

A

glycolysis

70
Q

What molecule can be a substitute for ATP to provide energy?

A

phosphocreatine

71
Q

What does phosphocreatine have that allows it to provide energy if broken?

A

high-energy phosphate bonds

72
Q

What enzyme transfers a phosphate from phosphocreatine to ADP?

A

creatine kinase

73
Q

What is twitch?

A

1 contraction/relaxation cycle

74
Q

What characteristic of phosphocreatine allows it to be used as a diagnostic tool?

A

different isoforms of creatin between the three muscle types

75
Q

What can high levels of creatine in circulation indicate? What molecule also escapes with creatin that can aid with the diagnosis if it is present at high levels in circulation?

A

indicates damage at that muscle type (such as cardiac) | troponin (also has different isoforms)

76
Q

What is a Neuromuscular Junction?

A

specialized synapse between muscle cells and neurons

77
Q

What is atrophy?

A

muscle cells start to die

78
Q

In which muscles are nicotinic ACh receptors (NAChR) found?

A

skeletal muscles

79
Q

In which muscles are muscarinic ACh receptors found?

A

smooth and cardiac muscles

80
Q

What causes Myasthenia gravis?

A

loss of acetylcholine receptors

81
Q

What is Myasthenia gravis?

A

autoimmune diseases attacking ACh receptors

82
Q

What is a power stroke?

A

movement of myosin head pulling F-actin closer

Cell Physiology (13 decks)

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