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A&P Quarter 2.2 > Muscle Histology III > Flashcards

Muscle Histology III Flashcards

1
Q

What is rigor mortis?

A

Hardening of the muscles and stiffening of the body

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2
Q

At a cellular level, what happens during rigor?

A

No More ATP is being produced you you cannot get Ca2+ out of the sarcoplasm back into the terminal cisternae of the SR. Cross bridging is promoted, but no ATP is produced to release the heads of the myosin from the F actin active sites.

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3
Q

When does rigor set in? When does it abate?

A

3-4 hours post mortem

48-60 hours with the beginning of decomp

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4
Q

What kind of paralysis does curare cause?

A

Flaccid

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5
Q

What is the mechanism of curare?

A

Binds to ACh receptors

Mimics ACh, so ACh itself cannot bind to receptors

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6
Q

What is the mechanism of botulism?

A

Prevents release of ACh at neuromuscular junction
Botulin toxin
No ACh in synaptic gap

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7
Q

What kind of paralysis does botulism cause?

A

Flaccid paralysis

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8
Q

What is the mechanism of tetanospasmin?

A

Blocks glycine release (inhibiting)

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9
Q

What kind of paralysis does tetanus cause?

A

Spastic

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10
Q

What is the mechanism of organophosphates?

A

Inhibits AChE by binding to AChE

Muscles cannot relax

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11
Q

What kind of paralysis is caused by pesticides?

A

Spastic

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12
Q

What is the mechanism of myasthenia graves?

A

An autoimmune disease

Antibodies bind to ACh receptors, damaging them

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13
Q

What kind of paralysis is caused by myasthenia graves?

A

Flaccid paralysis

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14
Q

What is the mechanism of polio?

A

A virus destroys motor neurons in brainstem and ventral horn of the spinal cord

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15
Q

What kind of paralysis comes from polio?

A

Flaccid

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16
Q

Muscles cannot turn all of the energy they consume into________ work, so they produce _____.

A

Mechanical

Heat

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17
Q

Most body heat is due to the ________ of skeletal muscle

A

contractions

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18
Q

When the body temperature falls, the _________ makes us shiver to increase heat up to _____%.

A

Hypothalamus

400%

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19
Q

In muscle histology, in what 3 places is ATP needed?

A

1- To bind myosin head to actin
2- To release myosin head from actin
3- To reconcentrate Ca2+ in the terminal cisternae

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20
Q

For muscle contraction, what must be bound to myosin?

A

An ATP

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21
Q

How is the ATP used by the myosin head?

A

An enzyme is present in the head ( myosin ATPase) hydrolyzes this ATP
Energy released by this process activates the head which shifts into an extended high energy position

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22
Q

For a muscle to relax, _____ breaks down any remaining ACh.

A

AChE

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23
Q

What is calsequestrin?

A

A protein that binds to Ca++ for storage.

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24
Q

What is muscle tone?

A

The CNS continually monitors and adjusts the length of the resting muscles, maintaining a state of partial contraction

25
Q

In which three areas is an O2 debt repaid?

A

1- O2 bound to myoglobin
2- O2 bound to hemoglobin
3- O2 dissolved in blood plasma

26
Q

What is aerobic cell respiration?

A

Requires O2, yields 38 ATP

27
Q

What is anaerobic cell respiration?

A

Doesn’t require O2, yields 2 ATP

28
Q

What generates lactic acid?

A

Anaerobic cell respiration

29
Q

What are the two types of skeletal muscle fibers?

A

SO (slow oxidative) or slow-twitch or red fibers and

FG (fast glycolic) or fast twitch or white fibers

30
Q

Which muscle fiber is well adapted for aerobic respiration and have abundant mitochondria, many surrounding blood vessels?

A

SO

31
Q

______ fibers have lots of myoglobin and _____ fibers have little myoglobin/

A

SO

FG

32
Q

What are some examples of SO muscles?

A

Postural muscles, respiration muscles, muscles for mastication

33
Q

What kind of person has a greater % of SO muscles?

A

Distance runners

34
Q

FG muscles are adapted for anaerobic respiration, they have high _____ reserves

A

glycine

35
Q

FG muscles contract more ________, and produce ________ as a byproduct.

A

Rapidly

Lactic acid

36
Q

What kind of person has more FG fibers?

A

Basketball players and sprinters

37
Q

What is an isotonic contraction?

A

Contraction with a change in length, but not tension

38
Q

What are the two types of isotonic contraction?

A

Concentric Isotonic

Eccentric Isotonic

39
Q

What is isotonic concentric contraction? An example?

A

A muscle shortens as it maintains tension

Ex: “Lift up baby”

40
Q

What is isotonic eccentric contraction? An example?

A

A muscle lengthens as it maintains tension

Ex: “Put down baby”

41
Q

What is isometric muscle contraction?

A

Contraction without a change in length

“Tension building up to allow you to lift something”

42
Q

What kinds of muscles have isometric contraction?

A

Found in postural muscles- “keeping us from sinking to the floor”

43
Q

Which tissues have myocytes in them?

A

Cardiac and smooth muscle, only

44
Q

Which muscle types contain sarcomeres?

A

Skeletal and cardiac

45
Q

How do cardiac cells communicate with the cell next door?

A

Thru gap junctions and intercalated discs

46
Q

Describe the SR of the cardiac cell

A

Sarcoplasmic reticulum is less developed and the T tubules are larger

47
Q

Larger T tubules allow cardiac muscle to….

A

Admit more Ca++ from the ECF

48
Q

What is the pacemaker of the heart?

A

The SA node

49
Q

The heart uses ________ respiration and is rich in _______ and glycogen.

A

Aerobic

myoglobin

50
Q

In cardiac cells this body takes up approximated 25% of the interior volume

A

Mitochondria

51
Q

The heart is highly resistant to fatigue, and does not do __________.

A

Recruitment

52
Q

Where is smooth muscle found?

A

Found as circular and longitudinal layers in GI, urinary, and reproductive

53
Q

Why doesn’t smooth muscle have sarcomeres?

A

Thick and thin filaments are present, but they are not aligned with each other, so they do not produce visible striations or sarcomeres

54
Q

How does smooth muscle get Ca++?

A

From the ECF. There are no T tubules.

55
Q

Which muscle type is capable of mitosis hyperplasia?

A

Smooth

56
Q

Why is mitosis and hyperplasia advantageous to smooth muscle?

A

An organ like the pregnant uterus can grow by adding more myocytes;
Smooth muscle heals well

57
Q

How much can smooth muscle stretch?

A

A lot.
Uterus: 8x
Bladder: 2.5x

58
Q

How is smooth muscle innervated?

A

Some smooth muscle does not have a nerve supply, and instead contracts due to ANS, temperature, hormones, or as a response to its own stretching

A&P Quarter 2.2 (22 decks)

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