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MCAT - biology > muscular system > Flashcards

muscular system Flashcards

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1
Q

___________ msucle is essential for supporting the bosy and facilitating movement

A

skeletal

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2
Q

the contraction of skeletal muscle also compresses ____________ structures and helps propel blood

A

venous

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3
Q

_____________ muscle is responsible for involuntary movement

A

smooth

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4
Q

_____________ muscle is able to maintain rhythmic contraction of the heart without nervous system input

A

cardiac

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5
Q

skeltal muscle is responsible for ________ movement

A

involuntary

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6
Q

skeletal muscle is innervated bu the ______________ nervous system

A

somatic

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7
Q

why does skeletal muscle appear striped?

A

arrangement of actin ad myosin into repeatin units called sacromeres

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8
Q

T / F - skeletal muscle is multinucleated

A

true

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9
Q

give some characteristics of red fibers

A

slow twitch (marathons)
high mitochondria content
high myoglobin content = red
aerobic energy pathways

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10
Q

give some characteristics of white fibers

A

fast twitch (sprints)
low mitochondria content
low myoglobin content = white

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11
Q

identify:
muscles that contract slowly. but can sustain activity

A

mostly red fibers

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12
Q

smooth muscle is innervated by the ___________ nervous system

A

autonomic

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13
Q

T / F - smooth muscle is stiated and contains a single nucleus

A

false, smooth muscle is not striated, but it does only contain a single nucleus in each cell

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14
Q

_____________ is the sustained contractions that is seen in blood vessels

A

tonus

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15
Q

what is myogenic activity?

A

smooth muscle can contract witjpit mervpis susym input

*reflexes

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16
Q

cardiac cells:
uni / multi nucleated?
involuntary / voluntary movement?
autonomic / somatic nervous system?
striated / nonstriated?

A

uninucleated
involuntary
autonomic
striated

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17
Q

cardiac muscle cells ared conected by ______________, which contain may _________

A

intercalated dics
gap junctions

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18
Q

what do gap junctions in cardiac cells allow for?

A

flow of ions directly between cells

allows for the rapid and coordinated depolarization of msucle cells and efficient contractio of cardiac muscle

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19
Q

T / F - cardiac cells have myogenic activity

A

true

*they define and maintain their own rhythm

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20
Q

starting at the ___________, depolarization spreads using conduction pathways to the ____________

A

sinoatrial (SA) node
atrioventricular (AV) node

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21
Q

after depolarization of the SA node, then to the AV node, it spreads to the ___________ and finally to the _____________

A

bundle of his
purkinje fibers

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22
Q

the vagus nerve provides parasympathetic outflow to the heart and (speeds / slows) the heart rate

A

slows

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23
Q

_____________ or _______________ binds to adrenergic receptors in the heart, causing increased heart rate

A

epinephrine
norepinephrine

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24
Q

epinephrine is made in the ______________
norepinephrine is made in the __________

A

epinephrine = sympathetic neurons
norepinephrine = adrenal medulla

25
Q

thick filaments are organized in bundles of ______________

A

myosin

26
Q

thin filaments are organized in bundles of __________

A

actin

27
Q

________ acts as a sprig and achors the actin and myosin filaments together, preventing excessive stretching of the muscle

A

titin

28
Q

__________ defines the boundaries of each sarcomere

A

Z line

29
Q

_________ runs down the center of the sarcomere, trhough the middle of the myosin filaments

A

M line

30
Q

_______ is the region containing exclusively thin filaments

A

I band

31
Q

_______ is the region containing only thick filaments

A

H zone

32
Q

______________ contains the thick filaments in their entirety, including any overlap with thin filaments

A

A band

33
Q

which of these areas becomes smaller during contraction? which ones remain the same?

I band
H zone
M line
Z line
A band

A

decrease:
H zone
I band
Z lines
M lines

same:
A band

34
Q

sarcomeres are attached end to end to form ____________

A

myofibrils

35
Q

myofibrils are surrounded by a covering known as ______________

A

sarcoplasmic reticulum

36
Q

the sarcoplasmic reticulum contains a high concentration of ________ ions

A

Ca2+

37
Q

_____________ is a modified cytoplasm located hyst outside the sarcoplasmic reticulum

A

sarcoplasm

38
Q

what is the cell membrane of a myocyte called?

A

sarcolemma

39
Q

__________ is many myofibrils arranged in parallel

A

myocyte or muscle fiber

40
Q

many myocytes in parallel form a __________

A

muscle

41
Q

muscular contraction starts at the _______________

A

neuromuscular junction

42
Q

the nervous syste communicates with muscles via _______ neurons

A

efferent (motor)

43
Q

the signal travels down the neuron until it reaches the nerve terminal, where __________ is released into the synapse

A

acetylcholine

44
Q

acetylcholine binds to receptors on the sarcolemma, causing ____________

A

depolarization

45
Q

when the action potential reaches the sarcoplasmic reticulum, __________ is released

A

Ca2+

46
Q

calcium binds to a regulatory subunit in ______________, triggering a change in the confirmation of ____________

A

binds to = troponin
reveals = tropomyosin

47
Q

explain the major steps fo the actin-myosin cross bridge cycle, starting with the resting stage

A
  1. resting stage, ATP hydrolyzed (ADP + P)
  2. Ca2+ binds to troponin, moves tropomyosin, myosin binds to actin
  3. powerstroke occurs, sarcomere contracts, ADP and P dissociate from myosin
  4. ATP binds to myosin which causes the detachment of myosin from actin, hydrolysis of ATP (ADP + P), recocks the myosin head
48
Q

without calcium, the myosin binding sites are covered by ____________ and contraction is prevented

A

tropomyosin

49
Q

_____________ is the response of a single muscle fiber to a brief stimulus at or above threshold

A

single twitch

50
Q

____________ is when contraction combine and become stronger and more prolonged

A

frequency summation

51
Q

_______________ is when contractions become so frequent that the muscle is unable to relax at all

A

tetanus

52
Q

what are the two supplemental energy reserves in muscle?

A
  1. creatine phosphate
  2. myoglobin
53
Q

T / F - myoglobin binds to O2 with high affinity

A

true

54
Q

fast twitch muscle fibers have (more / fewer) mitochondria and must rely on ____________ and ____________ to make ATP

A

fewer mitochondria
glycolysis and fermentation

55
Q

what are some conditions that would shift the oxyhemoglobin dissociation curve to the right?

A

low pH (high H+)
increased CO2 concentration
increased temp

56
Q

____________ is the difference between the amount of O2 needed by the muscles and the actual amount present

A

oxygen debt

57
Q

most lactic acid is converted into ____________ which can enter the CAC

A

pyruvate

58
Q
A

MCAT - biology (35 decks)

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