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ZOO*3600 > After Midterm > Flashcards

After Midterm Flashcards

1
Q

What are the three types of muscles?

A

skeletal muscles, cardiac muscles, smooth muscles

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2
Q

What is the major differences in the types of muscles?

A

how their cells are organized and how contraction is initiated

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3
Q

Which muscles are striated?

A

skeletal and cardiac

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4
Q

Which muscles are unstriated?

A

smooth muscles

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5
Q

Which muscles are voluntary?

A

skeletal muscles

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6
Q

which muscles are involuntary?

A

cardiac and smooth

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7
Q

How do you tell apart striated and unstriated muscles?

A

striated muscles have alternating light and dark bands

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8
Q

When are muscles categorized as voluntary?

A

if they are innervated by the motor division of the peripheral nervous system.

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9
Q

when are muscles categorized as involuntary?

A

if they are innervated by the autonomic division of the peripheral nervous system

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10
Q

what do smooth muscles include?

A
  • the muscles that line your blood vessels
  • your respiratory tract
  • the lining of your digestive system
  • form a muscle layer around many organs in your body.
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11
Q

what are muscles anchored by?

A

tendons

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12
Q

What are muscles made up of?

A

multinucleated cells that are called muscle fibers

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13
Q

What do muscle fibers originate from?

A

many embryonic muscle cells which are called myoblasts, fusing together to form multinucleated myotubes.

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14
Q

What are muscle fibers made of?

A

Muscle fibers are made of parallel subunits that are called myofibrils

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15
Q

what do the parallel arrangement of fibers and myofibrils allow for?

A

allows the fibers to generate force along a common axis

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16
Q

where are actin thin filaments anchored?

A

the z-disks

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17
Q

where are the myosin thin filaments anchored?

A

to the m-line

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18
Q

What are this filaments composed of?

A
  • 2 strands of actin that form a helix
  • tropomyosin
  • troponin complex
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19
Q

what happens at myosin binding sites?

A

thick filaments bind to thin filaments

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20
Q

what does the tropomyosin filament do at rest?

A

hide the myosin binding site

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21
Q

what do g-actin form?

A

long double-stranded polymers that twist together to form the helix.

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22
Q

How are myosin molecules connected?

A

by the tails

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23
Q

what does the head region of the myosin thick filament contain?

A

both an actin binding site and a site for binding ATP cross bridges

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24
Q

What are thick filaments composed of?

A

hundreds of identical myosin proteins

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25
Q

what is the number of cross bridges produced proportional to?

A

the total tension produced by a muscle fiber

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26
Q

what is a cross bridge?

A

physical interaction between the myosin head and the actin filament

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27
Q

what happens to sarcomeres during muscle contraction?

A

they shorten

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28
Q

why do muscle filaments shorten during contraction?

A

the thin filaments actively slide along the thick filaments towards the midline

29
Q

Do the lengths of the thick and thin filaments change during contraction?

A

no, the extent of overlap changes.

30
Q

what is the h-zone?

A

the distance between one dark band and the next dark band

31
Q

what is the binding of myosin a result of?

A

the hydrolysis of ATP

32
Q

what are the three steps of the cross bridge cycle?

A
  • the binding
  • the power stroke
  • the release
33
Q

what is responsible for the release of the myosin head from the actin thin filaments?

A

the binding of a new molecule of ATP

34
Q

What happens when intracellular calcium in the muscle is low?

A

he filamentous protein tropomyosin blocks the myosin binding site on actin

35
Q

What happens when the cellular concentration of calcium becomes elevated?

A

calcium binds to troponin

36
Q

what happens when calcium binds to troponin?

A

Binding of calcium to troponin drags tropomyosin filament off the myosin binding sites allowing the myosin head to form a cross bridge with the actin thin filaments

37
Q

what three proteins make up the troponin complex?

A

TNT, TNC, TNI

38
Q

What does TNT do?

A

directly interacts with tropomyosin

39
Q

what does TNC do?

A

contains the binding site for calcium

40
Q

what does TNI do?

A

the protein which keeps tropomyosin in its resting position where it covers all the binding sites for myosin

41
Q

what happens when your muscle cells run out of ATP?

A

rigamortis

42
Q

What causes cramps?

A

An imbalance in either ATP or calcium handling between the cytoplasm and the sarcoplasmic reticulum

43
Q

when do muscle fibers contract?

A

when a postsynaptic end plate potential at the neuromuscular junction causes a propagated action potential in the fiber sarcolemma

44
Q

how does an action potential in the muscle fiber change the free concentration of calcium in the cytosol of the muscle fiber?

A

t tubules will conduct action potentials into the cell interior causing calcium release from the sarcoplasmic reticulum that surrounds the myofibrils

45
Q

what is the source for regulatory calcium in skeletal muscles?

A

The calcium that comes from the storage compartment from the sarcoplasmic reticulum

46
Q

what are the 4 molecules that contribute to the control of free calcium in the cytosol of muscle cells?

A
  • dhpr receptor
  • ryr
  • calcium pumps
  • calsequestrin
47
Q

what are calcium pumps involved with?

A

continuously sequestering calcium from the cytoplasm of the muscle fiber

48
Q

what does calsequestrin do?

A

sequesters calcium from inside the sarcoplasmic reticulum.

49
Q

what is a twitch?

A

the relative amount of tension produced by a single AP

50
Q

What is the amount of tension produced during a single twitch proportional to?

A

the concentration of calcium in the cytoplasm

51
Q

How do you increase the size and strength of a contraction?

A

a series of APs to depolarize the muscle fiber

52
Q

what is temporal summation?

A

the addition of tension due to rapid stimulation

53
Q

what is a motor unit?

A

All of the muscle fibers that are innervated by a single motor neuron

54
Q

How can neurons increase the amount of tension?

A
  • increasing action potential frequency (temporal summation)
  • recruiting more motor units
55
Q

True or false:

all myosin head ATPase can hydrolyze ATP at the same speed to form cross bridges at the same speed.

A

false

56
Q

what is the force generated by a given sarcomere proportional to?

A

the number of cross bridges that are formed

57
Q

how can sarcomeres generate different amounts of force?

A

they need to produce more cross bridges

58
Q

True or false:
The higher the load the more difficult it becomes for the myosin heads to slide the thin filaments towards the middle the sarcomere and to shorten those sarcomeres.

A

true

59
Q

what is an isometric contraction?

A

a contraction of the muscle without movement of the skeletal elements

60
Q

what is force proportional to?

A

the cross sectional area of a muscle.

61
Q

what is the rate at which a muscle can work dependent on?

A

It’s rate of ATP production.

62
Q

True or false: ATP is needed for both muscle contraction and muscle relation

A

true

63
Q

Why is ATP required for relaxation?

A

you need to pump the calcium that was released from the sarcoplasmic reticulum from the cytosol back into the storage compartment in the sarcoplasmic reticulum.

64
Q

what is creatine phosphate?

A

a high energy molecule that can be stored in the muscle

65
Q

when is calcium an effective signal?

A

when it’s lifespan is extremely short

66
Q

what is responsible for the myosin head extending and binding?

A

ATP being hydrolyzed to ATP

67
Q

what is responsible for the power stroke and the sliding of filaments?

A

Release of the high energy phosphate

68
Q

what is responsible for the myosin head detaching from the actin filaments?

A

attachment of a new ATP molecule to the myosin head

ZOO*3600 (2 decks)

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