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

Muscle Cells and Tissues (Chapter Outline) Flashcards

(57 cards)

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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?

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A

Switch contraction on and off

24
Q

What are the 2 regulatory protein muscle strands?

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A

Tropomyosin and troponin

25
What are the 2 contractile proteins in a muscle cell?
Myosin and actin
26
What do structural proteins do in muscle cells, and what is the main one that anchors the thick filaments to the Z lines?
Align and stabilize myofibrils Provide elasticity and extensibility Titin is the large protein that anchors thick filament to Z line
27
According to the sliding filament mechanism of muscle contraction, the sarcomere shortens, but does the length of the filaments change?
No, the length of the filaments does not change, they just squish together.
28
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.
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
What is the name of the site where a somatic motor neuron communicates with a muscle fiber?
Neuromuscular junction
30
In a sarcomere, what contractile protein forms the thick filaments? Thin filaments?
``` Thick = myosin Thin = actin ```
31
What is a synergist muscle?
Helps a prime mover do its job
32
What is myoglobin?
Oxygen storage molecule in muscle
33
What neurotransmitter is released at neuromuscular junctions?
Acetylcholine
34
True or false: an aponeurosis is a broad, flat tendon
True
35
True or false: Muscle contraction is accomplished by shortening the thin filaments
False
36
True or false: ATP is required for both muscle contraction and relaxation
True
37
Is red muscle slow or fast muscle? White?
``` Red = slow White = fast ```
38
Where are synaptic terminals located?
At the ends of axon branches of somatic motor neurons
39
What do synaptic vesicles hold?
Acetylcholine
40
When the neurotransmitter gets released by the neuron into the synaptic cleft, it diffuses across the cleft and binds to _________?
Receptors on the sarcolemma of the muscle fiber
41
What are ligand-gated ion channels?
They open and close based on chemical signals (neurotransmitters) Open when ACh binds to them
42
What is the motor end plate?
The area of the neuromuscular junction where ACh receptors form ligand-gated ion channels
43
What are the 4 steps of excitation of a muscle?
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 3. ACh activity is terminated
44
How is an action potential produced?
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
What makes excitation-contraction coupling different from involuntary muscle contraction?
It's initiated by an action potential traveling down the T tubules
46
How are calcium ions pumped back into the sarcoplasmic reticulum after they are released from the troponin on the thin filament?
Active transport pumps (using ATP)
47
What is a twitch?
A brief contraction due to a single nerve impulse causing a single action potential
48
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
1. Frequency of nerve stimulations | 2. Availability of ATP
49
What are 2 sources of glucose for muscle cell function?
1. Muscle fibers (glucose stores in them) | 2. Bloodstream (by facilitated diffusion into muscle fiber)
50
What are 2 sources of oxygen for muscle cell function?
1. Myoglobin (released from muscle fibers) | 2. Blood capillaries (by diffusion)
51
What is a motor unit?
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
What are the 3 phases visible in a myogram after the stimulus?
1. Latent period 2. Contraction phase 3. Relaxation phase
53
What is wave summation?
Repeated stimulations BEFORE relaxation is complete causes stronger contraction
54
What does treppe look like in a myogram?
Steps
55
What is the difference between an isotonic and isometric muscle contraction?
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
There are 2 kinds of isotonic contractions in muscles: concentric and eccentric. Which is which?
Concentric: muscle shortens Eccentric: muscle lengthens
57
How do muscle cells regenerate, since they can't divide?
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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