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MSK Exam 2 > Lecture 4: Skeletal Muscle and Nerve Tissue > Flashcards

Lecture 4: Skeletal Muscle and Nerve Tissue Flashcards

1
Q

Simply put, how does contraction occur?

A

Actin (thin filaments) and myosin (thick filaments) slide past each other in myofibrils in the cytoplasm

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2
Q

What is actin made of?

A

G-Actin Monomers

(globular protiens)

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3
Q

What two chains does Myosin have?

A

Heavy chain with a globular head

Light chain

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4
Q

How can you differentiate between skeletal, cardiac, and smooth muscle?

A

Skeletal: Striated and Voluntary

Cardiac: Striated and Involuntary

Smooth: Non-striated and Involuntary

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5
Q

From smallest unit to largest, what are the divisions of a muscle?

A

Sarcomere -> Myofibrils -> Myocyte (Myofiber) -> Fascicle -> Muscle

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6
Q

What connective tissue separates myofibers?

A

Endomysium

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7
Q

What connective tissue separates fascicles?

A

Perimysium

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8
Q

What fascial covering surrounds the entire muscle itself?

A

Epimysium

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9
Q

What features can be used to identify Skeletal Muscle, especially in a histological slide?

A

Peripheral nucleii and Striations

Myofibers: Multinculeaded cylinders in the periphery of cell

Myofibrils: In the cytoplasm

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10
Q

What is a sarcomere?

A

Basic structure of myofibril

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11
Q

What serves as the defined border of a sarcomere?

A

Z disks

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12
Q

What is the Sarcoplasm?

A

Cytoplasm of a Muscle Cell

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13
Q

What is Sarcoplasmic Reticulum?

What is stored in there?

A

Tubular system which acts like smooth ER

-Calcium is stored

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14
Q

What is the Sarcolemma?

A

The membrane around myocytes that penetrates the muscle cell as T tubules

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15
Q

What are Transverse (T) Tubules?

A

Invaginations of sarcolemma

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16
Q

What connects the Transverse Tubule to the Terminal Cisternae?

What do they do?

A

“End Feet”

Allow for calcium release

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17
Q

What does the Terminal Cisternae do?

A

Dilated ends of Sarcoplasmic Reticulum that releases Calcium to trigger muscle contraction

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18
Q

What is marked here as 1?

What does it contain?

A

I Band

-only actin thin filaments

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19
Q

What is marked here as 2?

What is found here?

A

A Band

-Overlap of actin and myosin and H zone

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20
Q

What is marked here as 3?

What is found here?

A

H Zone

-only myosin thick filaments

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21
Q

What is marked here as 4?

What is found here?

A

M Line

-anchor site for myosin thick filaments

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22
Q

What is marked here as 5?

What is found here?

A

Z Line

Anchor site for actin thin filaments

23
Q

What attaches to the Z disk?

A

Actin and Titin (which in turn holds myosin)

24
Q

What holds the Myosin to the Z disk, thus holding Myosin in place?

A

Titin protiens

25
Q

What all is contained within the H Zone?

A

Myosin fibers and the M line

26
Q

What is contained within the I band?

A

Actin

The Z Disk

(straddles sarcomeres)

27
Q

What is defined as the A band?

A

Distance from end to end of myosin within one sarcomere.

28
Q

Does the A Band shorten during contraction?

A

No. Only the H Zone and the I band shorten

29
Q

Where are myosin going one direction attached to the myosin going the other direction?

A

M line / M disc

30
Q

What two regions of a Myofibril shorten during muscle contraction?

A

The H Zone and the I Band

31
Q

What does Tropomyosin do?

A

Wraps between actin strands and holds troponin

32
Q

What keeps the muscles from contracting all the time?

A

Tropomyosin blocks the myosin binding sites

33
Q

What does Calcium do to incite muscle contraction?

A

It binds to Troponin, which then causes Tropomyosin to change conformation, and no longer block the Myosin binding sites on the Actin Filament

34
Q

What are the basic characteristics of Type 1 muscle fibers?

A
  • Slow ATPases
  • Slow Contractions and low power (e.g. muscles in back)
  • Low fatigability
  • Many mitochondria and very aerobic
  • Abundant Myoglobin for O2 (gives red color)
35
Q

What is a Type IIa Muscle Fiber?

A
  • Largest and most prevalent (seen in most of body)
  • Intertmediate ATPase that provides power
  • Primary aerobic
36
Q

What are the basic characteristics of Type IIb Muscle Fibers?

A
  • Fast ATPase and largerly anaerbic
  • Rapid Fatigue
  • Low myoglobin content
37
Q

What are the major parts of a neuron?

A
  • Cell Body: processes electrical information
  • Cell Processes
    • Dendrites: carries electrical signals toward cell body
    • Axons: carries electrical signals away from cell body
  • Synapse: Transfer of electric signals from axon terminal of one nerve to an effector cell
38
Q

What is the Nissl substance?

A

Rough ER that makes a lot of neurotransmitters and protein to maintain neurons

39
Q

What is the function of the Axon Hillock?

A

Sums up all of the action potentials from the dendrites, and sends a signal down the axon if it is sufficient.

40
Q

What is this type of neuron?

How many dendrites and axons for this neuron?

A

Multipolar Neuron

-Multiple dendrites, one axon

41
Q

What is this type of neuron?

How many dendrites and axons for this neuron?

A

Bipolar Neuron

-Single dendrite (with multiple extensions) and one axon

42
Q

What is this type of neuron?

What are the characteristics of this neuron?

A

Unipolar Neuron

A cell body connected to a cell process with a dendrite branch and an axon branch

43
Q

Do Schwann cells wrap around parts of single axons or many axons together?

A

Parts of a single axon in the PNS

44
Q

Do Oligodendrocytes wrap around parts of single axons or many axons together?

A

Many axons together in the CNS

45
Q

What connective tissue layer wraps a single myelinated or unmyelinated axon?

It is connective tissue between axons

A

Endoneurium

46
Q

What connective tissue layer wraps a fascicle of nerve fibers together?

A

Perineurium

47
Q

What is the connective tissue layer surrounding the outside of the entire spinal nerve?

A

Epineurium

48
Q

In broad terms, how does the chemical synapse work?

A

Step 1: Synpatic vessels in the presynaptic knob release a NT into the synpatic cleft via exocytosis.

Step 2: NT binds to a receptor on the postsynpatic membrane

Step 3: Postsynpatic cell is now stimulated

49
Q

How does the neuromusclar junction work?

A

Step 1: Acetylcholine is released into synaptic cleft

Step 2: Acetylcholine stimulates sarcolemma and excites the muscle fiber. This stimulus is carried to T tubules to initiate contraction

Step 3: Acetylcholine is broken down in synpatic cleft, ending its signal.

50
Q

What is an intrafusal muscle fiber?

What are its two compartments?

A

Specialized fibers inside muscle spindle

Nuclear Bag Fibers: Detect change in length and degree of tension

Nuclear Chain Fibers: Detect static muscle length

51
Q

What is an extrafusal muscle fiber?

A

Muscle fiber outside muscle spindle under voluntary control,

-In charge of contracting the muscle fibers

52
Q

What is the function of Alpha-Motor nerve fibers?

A

Sends the signal to contract to a muscle to extrafusal fibers

53
Q

Why is it important to have electrical impulses shuttled into the cell?

A

So that the myocyte can contract all at once, instead of from the outside in.

MSK Exam 2 (22 decks)

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