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A&P I > Muscle Cells and Tissues (Chapter Outline) > Flashcards

Muscle Cells and Tissues (Chapter Outline) Flashcards

1
Q

Is a muscle fiber (cell) single nucleate or multinucleate?

A

Multinucleate

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2
Q

What is the endomysium of a muscle cell?

A

Elastic connective tissue sheath around individual muscle FIBERS

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3
Q

What is a fascicle in a muscle?

A

Bundle of muscle fibers (10-100 fibers)

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4
Q

What is the perimysium (in a muscle)?

A

Dense irregular connective tissue sheath around the FASCICLE

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5
Q

A muscle is made of bundles of _______ and is held together by the _________.

A

Fascicles; Epimysium

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6
Q

What kind of connective tissue is a tendon made of?

A

Dense regular connective tissue

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7
Q

Which layer(s) of the connective tissue sheaths do tendons attach to?

A

All 3 sheaths

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8
Q

Tendons attach _____ to _____.

A

Muscles; Periosteum of bone

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9
Q

What is an aponeurosis?

A

Broad flat tendon sheet

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10
Q

What are the 3 layers of connective sheaths that surround muscle components?

A

Inner - around muscle fibers: Endomyseum
Middle - around fascicles: Perimyseum
Outer: around muscle: Epimyseum

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11
Q

What do somatic motor neurons stimulate muscles to do?

A

Contract

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12
Q

What is the difference between sarcolemma, sarcoplasm, and sarcoplasmic reticulum?

A

Sarcolemma: Plasma membrane of cell
Sarcoplasm: cytoplasm of muscle cell
Sarcoplasmic reticulum: Network of sacs and tubules

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13
Q

What is the name for the invaginations of the sarcolemma into the center of the muscle fiber? They open to interstitial space and are full of interstitial tubules.

A

T tubules

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14
Q

What are T tubules made from? What are they filled with?

A

Invaginations of the sarcolemma that go into the middle of the muscle fiber. Filled with interstitial fluid.

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15
Q

What is the sarcoplasm, and what floats around in it?

A

Cytoplasm of muscle cell

Glycogen, myoglobin, and lots of mitochondria (for making ATP for muscle contraction)

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16
Q

What is the sarcoplasmic reticulum? What are terminal cisterns?

A

Network of sacs and tubules

Terminal cisterns are dilated sacs on either side of the T tubules (triad)

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17
Q

Where are calcium ions stored for muscle contractions?

A

In the sarcoplasmic reticulum

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18
Q

A band and I band: which is light, and which is dark?

A

A band: dark

I band: light

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19
Q

What is in the center of the A band on a sarcomere?

A

The M line

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20
Q

What is in the middle of the I band on a sarcomere?

A

The Z lines

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21
Q

What do myosatellite cells do?

A

They are a few myoblasts that remain in adult muscle. Help repair damaged muscle.

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22
Q

What are the 3 kinds of muscle proteins?

A
  1. Contractile proteins
  2. Regulatory proteins
  3. Structural proteins
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23
Q

What do regulatory proteins in the muscle do?

A

Switch contraction on and off

24
Q

What are the 2 regulatory protein muscle strands?

A

Tropomyosin and troponin

25
Q

What are the 2 contractile proteins in a muscle cell?

A

Myosin and actin

26
Q

What do structural proteins do in muscle cells, and what is the main one that anchors the thick filaments to the Z lines?

A

Align and stabilize myofibrils
Provide elasticity and extensibility
Titin is the large protein that anchors thick filament to Z line

27
Q

According to the sliding filament mechanism of muscle contraction, the sarcomere shortens, but does the length of the filaments change?

A

No, the length of the filaments does not change, they just squish together.

28
Q

What are the 3 steps of contraction?

  1. Calcium is released from the ________.
  2. That calcium binds to ______ on the thin filament.
  3. This binding causes a shape-shifting and frees up the _______-binding sites on the thin filament.
A
  1. Sarcoplasmic reticulum releases stored calcium ions
  2. Those now-free calcium ions bind to troponin on the thin filament
  3. When the calcium binds with the troponin, the troponin changes shape and frees up the myosin-binding sites on the thin filament
29
Q

What is the name of the site where a somatic motor neuron communicates with a muscle fiber?

A

Neuromuscular junction

30
Q

In a sarcomere, what contractile protein forms the thick filaments? Thin filaments?

A 
Thick = myosin
Thin = actin
31
Q

What is a synergist muscle?

A

Helps a prime mover do its job

32
Q

What is myoglobin?

A

Oxygen storage molecule in muscle

33
Q

What neurotransmitter is released at neuromuscular junctions?

A

Acetylcholine

34
Q

True or false: an aponeurosis is a broad, flat tendon

A

True

35
Q

True or false: Muscle contraction is accomplished by shortening the thin filaments

A

False

36
Q

True or false: ATP is required for both muscle contraction and relaxation

A

True

37
Q

Is red muscle slow or fast muscle? White?

A 
Red = slow
White = fast
38
Q

Where are synaptic terminals located?

A

At the ends of axon branches of somatic motor neurons

39
Q

What do synaptic vesicles hold?

A

Acetylcholine

40
Q

When the neurotransmitter gets released by the neuron into the synaptic cleft, it diffuses across the cleft and binds to _________?

A

Receptors on the sarcolemma of the muscle fiber

41
Q

What are ligand-gated ion channels?

A

They open and close based on chemical signals (neurotransmitters)
Open when ACh binds to them

42
Q

What is the motor end plate?

A

The area of the neuromuscular junction where ACh receptors form ligand-gated ion channels

43
Q

What are the 4 steps of excitation of a muscle?

A
  1. ACh is released into synaptic cleft of neuromuscular junction
  2. ACh diffuses to the motor end plate and binds to receptors, opening ligand-gated channels
  3. Action potential is produced
  4. ACh activity is terminated
44
Q

How is an action potential produced?

A
  1. Sodium (Na+) flows into the muscle fiber near the sarcolemma and makes the charge inside the cell more positive.
  2. The change in charge opens voltage-gated sodium channels in sarcolemma, causing waves of electrical current to flow (propogate) both ways down the muscle fiber along the sarcolemma and T tubules
45
Q

What makes excitation-contraction coupling different from involuntary muscle contraction?

A

It’s initiated by an action potential traveling down the T tubules

46
Q

How are calcium ions pumped back into the sarcoplasmic reticulum after they are released from the troponin on the thin filament?

A

Active transport pumps (using ATP)

47
Q

What is a twitch?

A

A brief contraction due to a single nerve impulse causing a single action potential

48
Q

What 2 things does the amount of contraction (tension) in a muscle fiber depend on in order to be able to function?

  1. Stimulus
  2. Fuel
A
  1. Frequency of nerve stimulations

2. Availability of ATP

49
Q

What are 2 sources of glucose for muscle cell function?

A
  1. Muscle fibers (glucose stores in them)

2. Bloodstream (by facilitated diffusion into muscle fiber)

50
Q

What are 2 sources of oxygen for muscle cell function?

A
  1. Myoglobin (released from muscle fibers)

2. Blood capillaries (by diffusion)

51
Q

What is a motor unit?

A

A somatic motor neuron and all of the muscle fibers it stimulates (average is 150, but can be large or small bundles for fine/gross motor function)

52
Q

What are the 3 phases visible in a myogram after the stimulus?

A
  1. Latent period
  2. Contraction phase
  3. Relaxation phase
53
Q

What is wave summation?

A

Repeated stimulations BEFORE relaxation is complete causes stronger contraction

54
Q

What does treppe look like in a myogram?

A

Steps

55
Q

What is the difference between an isotonic and isometric muscle contraction?

A

Isotonic - changes length of the muscles to move body parts

Isometric - Creates tension on muscles but no movement occurs (like pushing against a wall)

56
Q

There are 2 kinds of isotonic contractions in muscles: concentric and eccentric. Which is which?

A

Concentric: muscle shortens
Eccentric: muscle lengthens

57
Q

How do muscle cells regenerate, since they can’t divide?

A

Hypertrophy - increase cell size due to more thick and thin filaments formed
Satellite cells regenerate fibers - contributes a little to growth

A&P I (11 decks)

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