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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
what is the number of cross bridges produced proportional to?
the total tension produced by a muscle fiber
26
what is a cross bridge?
physical interaction between the myosin head and the actin filament
27
what happens to sarcomeres during muscle contraction?
they shorten
28
why do muscle filaments shorten during contraction?
the thin filaments actively slide along the thick filaments towards the midline
29
Do the lengths of the thick and thin filaments change during contraction?
no, the extent of overlap changes.
30
what is the h-zone?
the distance between one dark band and the next dark band
31
what is the binding of myosin a result of?
the hydrolysis of ATP
32
what are the three steps of the cross bridge cycle?
- the binding - the power stroke - the release
33
what is responsible for the release of the myosin head from the actin thin filaments?
the binding of a new molecule of ATP
34
What happens when intracellular calcium in the muscle is low?
he filamentous protein tropomyosin blocks the myosin binding site on actin
35
What happens when the cellular concentration of calcium becomes elevated?
calcium binds to troponin
36
what happens when calcium binds to troponin?
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
what three proteins make up the troponin complex?
TNT, TNC, TNI
38
What does TNT do?
directly interacts with tropomyosin
39
what does TNC do?
contains the binding site for calcium
40
what does TNI do?
the protein which keeps tropomyosin in its resting position where it covers all the binding sites for myosin
41
what happens when your muscle cells run out of ATP?
rigamortis
42
What causes cramps?
An imbalance in either ATP or calcium handling between the cytoplasm and the sarcoplasmic reticulum
43
when do muscle fibers contract?
when a postsynaptic end plate potential at the neuromuscular junction causes a propagated action potential in the fiber sarcolemma
44
how does an action potential in the muscle fiber change the free concentration of calcium in the cytosol of the muscle fiber?
t tubules will conduct action potentials into the cell interior causing calcium release from the sarcoplasmic reticulum that surrounds the myofibrils
45
what is the source for regulatory calcium in skeletal muscles?
The calcium that comes from the storage compartment from the sarcoplasmic reticulum
46
what are the 4 molecules that contribute to the control of free calcium in the cytosol of muscle cells?
- dhpr receptor - ryr - calcium pumps - calsequestrin
47
what are calcium pumps involved with?
continuously sequestering calcium from the cytoplasm of the muscle fiber
48
what does calsequestrin do?
sequesters calcium from inside the sarcoplasmic reticulum.
49
what is a twitch?
the relative amount of tension produced by a single AP
50
What is the amount of tension produced during a single twitch proportional to?
the concentration of calcium in the cytoplasm
51
How do you increase the size and strength of a contraction?
a series of APs to depolarize the muscle fiber
52
what is temporal summation?
the addition of tension due to rapid stimulation
53
what is a motor unit?
All of the muscle fibers that are innervated by a single motor neuron
54
How can neurons increase the amount of tension?
- increasing action potential frequency (temporal summation) - recruiting more motor units
55
True or false: | all myosin head ATPase can hydrolyze ATP at the same speed to form cross bridges at the same speed.
false
56
what is the force generated by a given sarcomere proportional to?
the number of cross bridges that are formed
57
how can sarcomeres generate different amounts of force?
they need to produce more cross bridges
58
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.
true
59
what is an isometric contraction?
a contraction of the muscle without movement of the skeletal elements
60
what is force proportional to?
the cross sectional area of a muscle.
61
what is the rate at which a muscle can work dependent on?
It's rate of ATP production.
62
True or false: ATP is needed for both muscle contraction and muscle relation
true
63
Why is ATP required for relaxation?
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
what is creatine phosphate?
a high energy molecule that can be stored in the muscle
65
when is calcium an effective signal?
when it's lifespan is extremely short
66
what is responsible for the myosin head extending and binding?
ATP being hydrolyzed to ATP
67
what is responsible for the power stroke and the sliding of filaments?
Release of the high energy phosphate
68
what is responsible for the myosin head detaching from the actin filaments?
attachment of a new ATP molecule to the myosin head

ZOO*3600 (2 decks)

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