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Cell Physiology > Lectures 12-13 > Flashcards

Lectures 12-13 Flashcards

1
Q

What is a motor unit?

A

neuron + skeletal muscle (which has multiple muscle fibers)

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2
Q

What will happen if the skeletal muscles have not been stimulated but a motor neuron?

A

muscle will undergo atrophy = loose muscle mass

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3
Q

Why does the sarcolemma of the motor end-plate have a lot of receptors?

A

so it can increase the response to the neurotransmitter

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4
Q

What are nicotinic acetylcholine (ACh) receptors?

A

ligand-gated channels that conduct sodium and potassium ions

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5
Q

Which ion are nicotinic ACh receptors conduct more of?

A

sodium

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6
Q

What is signal termination at the neuromuscular junction?

A

when ACh is broken down by acetylcholinesterase into choline and acetyl

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7
Q

What does the variability of the ACh receptors allow?

A

toxins to bind to skeletal muscle receptors but not that which are involved in the ANS (somatic only)

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8
Q

How many subunits are nicotinic ACh receptor made up of?

A

5 (same as GABA receptors)

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9
Q

How many ACh molecules bind to nicotinic ACh receptors? What does this lead to?

A

two | net sodium influx = depolarization of muscle fiber

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10
Q

What is cooperativity binding in reference to ACh binding to nicotinic ACh receptors?

A

one ACh binding to nicotinic ACh receptor increases the affinity of nicotinic ACh receptor for more ACh to bind to it

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11
Q

What is the Hill coefficient for cooperativity?

A

≥ 2

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12
Q

How does cooperativity binding occur?

A

first ligand binding to receptor = causes allosteric changes to the next binding site on receptor | allosteric changes must occur for subsequent ligand-binding

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13
Q

What does cooperativity indicate about a ligand-receptor relationship?

A

there are at least 2 binding sites on the receptor

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14
Q

What type of receptors are muscarinic ACh receptors?

A

G-protein coupled receptor

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15
Q

What are the different types of muscarinic ACh receptors?

A

M1, M2, M3

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16
Q

What happens when ACh binds to muscarinic ACh receptors?

A

activates second messengers &raquo_space;> signaling cascade &raquo_space;> increas calcium levels in sarcoplasm

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17
Q

What are the 5 second messengers?

A

PIP2, IP3, DAG, PLC, AC

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18
Q

What is the only gas neurotransmitter?

A

nitric oxide (NO)

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19
Q

What are 2 other effects that can occur due to signaling cascade?

A

gene expression | opening of channels

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20
Q

What is muscle fatigue?

A

reversible condition in which a muscle is no longer able to generate or sustain power input

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21
Q

What is central fatigue?

A

originates from CNS | psychological fatigue

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22
Q

What are the 3 characteristics explaining fatigue?

A

highly variable | complex mechanism | aerobic or anaerobic

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23
Q

What is peripheral fatigue? What is it due to?

A

physiological fatigue originating at the muscle level | due to EC-coupling failure

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24
Q

How can fatigue be protective?

A

muscle releases a compound due to too much exercise &raquo_space;> compound causes acid build-up = signals to the brain to stop sending impulses so acid build-up doesn’t worsen

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25
Q

What type of classification is used to classify skeletal muscle?

A

based on the isoform of the myosin head

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26
Q

What are the 3 types of skeletal muscle?

A

slow twitch (type 1) | fast-twitch oxidative/glycolytic (type 2A) | fast-twitch glycolytic (2X)

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27
Q

What is myoglobin?

A

red protein in the skeletal muscles containing heme that oxygen binds to

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28
Q

What are fast-twitch movements used for?

A

fast-quick movements (ie: running)

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29
Q

What are slow-twitch movements used for?

A

posture and walking

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30
Q

How can a slow-twitch muscle fiber change into a fast-twitch muscle fiber (vice-versa)?

A

with training

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31
Q

What is tetanus?

A

when the summation of contractions are close to one another

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32
Q

What is the summation of contractions in skeletal muscles?

A

motor-neuron fires again before muscle has the chance to relax from previous twitch

33
Q

What is a tetanus contraction?

A

sustained muscle contraction induced when motor neuron sends APs at a high rate

34
Q

What is unfused tetanus?

A

motor neuron sends multiple stimulations but muscle relaxes slightly between stimuli

35
Q

What is complete tetanus?

A

all muscles contracting, no relaxation phase | can break bones

36
Q

What is the length and tension relationship of myosin and actin?

A

sweet-spot certain length of myosin-acton cross-bridges that allows muscles to perform the most and give the highest tension

37
Q

What happens if there is not enough cross-bridges happening in the sarcomere?

A

no force generated = no tension

38
Q

What is isometric contraction?

A

sarcomeres shorten = generates force but doesn’t move load | elastic elements stretch to sustain load w/o moving = muscle stays same length

39
Q

What is isotonic contraction?

A

(happens after isometric contraction) sarcomeres shorten more | elastic elements already stretched to capacity = muscle length shortens = creates enough force to move load

40
Q

What allows isometric contractions?

A

elastic elements

41
Q

What are proprioceptors?

A

sensory receptors in the skeletal muscles, joints, ligaments

42
Q

What is the Golgi Tendon Organs (GTO)?

A

connects muscle and tendon

43
Q

What are the 2 things the golgi tendon organ consist of?

A

sensory neurons | collagen fibers

44
Q

Where are golgi tendon organs found?

A

on the tendon just before the muscle

45
Q

What is the function of muscle spindles?

A

send information to CNS every time when muscles stretch

46
Q

Where are the muscle spindles located?

A

buried on the surface within the muscle fibers

47
Q

What are the 2 things that muscle spindles consist of?

A

gamma motor neurons | sensory neurons

48
Q

What is special about the central region of the muscle spindle?

A

no myofibrils | innervated by sensory neurons

49
Q

What type of reflex is the patellar tendon reflex (knee jerk)?

A

simple reflex

50
Q

Why can the patellar tendon reflex still work when the brain is severed from the spinal cord?

A

reflex is purely integrated within the spinal cord = don’t need brain to do this

51
Q

What type of reflex is the crossed extensor reflex? Why?

A

complex | one side = connected to the directly affected limb, other side will provide balance = both sides of spinal cord involved | interneurons involved

52
Q

What is the cardiovascular system?

A

series of tubes filled with fluid connected to a pump (heart)

53
Q

What is the primary function of the cardiovascular system?

A

transport material = nutrients, water, gases enter»>move throughout body»>eliminate waste

54
Q

What are the 2 blood vessels?

A

arteries | veins

55
Q

What is the function of red blood cells?

A

transport and deliver oxygen | eliminate CO2

56
Q

How many lobes are on each side of the lungs?

A

left = 2 | right = 3

57
Q

What direction do veins go?

A

TO the heart

58
Q

What direction do arteries go?

A

AWAY from heart (Aorta = Artery = Away)

59
Q

What is the function of the connective tissue in the heart?

A

ensures one-way blood flow, prevents backflow = prevents deO2 blood from mixing with O2 blood

60
Q

What is happening in the heart when you hear the “lub-dub” noise?

A

valves CLOSING

61
Q

What is the function of check valves?

A

prevent backflow

62
Q

What are the 3 factors that prevent back-flow of blood?

A

heart connective tissue | valves | pressure changes

63
Q

What does “AV” stand for in AV valves? What are the 2 AV valves and where are they located?

A

atrioventricular valve | tricuspid (3 cusps) = Right side | bicuspid (2 cusps, mitral valve) = Left side

64
Q

What is the function of semilunar valves? What are the 2 types?

A

ensures blood does not flow back into ventricles | pulmonary (to the lungs) and aortic (to the body)

65
Q

What is pressure measured in?

A

mmHg

66
Q

The closer the vasculature is to the aorta, the _____ the pressure. As you move away from the heart from the aorta, the pressure _______.

A

higher | decreases

67
Q

What characteristic allows the aorta to withstand the high pressure?

A

thick walls of the aorta

68
Q

What is aortic embolism?

A

when aorta explodes because the muscle fails

69
Q

How thick are the walls of veins?

A

thinner than arteries, more flimsy, can collapse

70
Q

Which vessel is blood supposed to be drawn from?

A

veins (deO2 blood)

71
Q

What is the pericardium?

A

membranous fluid-filled sace that encases the heart

72
Q

Why is it important that the heart functions as one unit?

A

the ANS only makes contact with one part of the heart

73
Q

What are intercalated disks in cardiac muscle?

A

accumulation of gap junctions = allow electrical continuity from one fiber to another | contains desmosomes

74
Q

What are desmosomes and its 3 functions?

A

type of junction | connects cardiac fibers together | ensures heart functions as one unit | allows material to flow through fibers

75
Q

What is the sodium-calcium exchanger?

A

membrane transporter that pumps Ca2+ out of cell | secondary active anti-port (uses gradient, not ATP)

76
Q

In cardiac muscle contraction, what does calcium bind to in order for contraction to occur?

A

troponin

77
Q

What type of refractory period do cardiac muscles have and why?

A

absolute refractory period | contractions need to be fully completed in order to properly pump blood

78
Q

How long is the absolute refractory period in cardiac muscles?

A

almost as long as the action potential itself | important for heart to go through full relaxation/contraction cycle to properly function

79
Q

What are the 3 sets of delays in heart action potentials?

A

sodium channels need to open first | calcium channels open very late | opening of potassium channels is very slow (different isoform)

Cell Physiology (13 decks)

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