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PHSL231 > Lecture 9 > Flashcards

Lecture 9 Flashcards

1
Q

Whats the anatomy of skeletal muscle?

A

muscle -> fascicles -> fiber -> myofibril

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2
Q

What myofilaments are there?

A

Thick (myosin) and thin (actin)

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3
Q

Do muscle cells have single or multiple nuclei?

A

Multiple

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4
Q

What is the individual contractile unit of a myofibril?

A

Sarcomere

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5
Q

What structures define the region of the sarcomere?

A

Z-lines

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6
Q

What does the I band contain?

A

Actin

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7
Q

What do the A bands contain?

A

Actin and Myosin

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8
Q

What does the H zone contain?

A

myosin

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9
Q

Where is the H zone located?

A

The centre of the A band

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10
Q

What is the M line?

A

The centre of the H zone (myosin). it contains proteins which organise and align the myosin.

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11
Q

What is the muscle’s length if it is resting?

A

Long

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12
Q

What is the muscle’s length if it is contracting?

A

Short

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13
Q

What happens when a muscle is partially contracted?

A

The actin and myosin filament slide over each other. The Z disc get closer together. the A band stays the same, and the H zone gets smaller.

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14
Q

TRUE or FALSE - skeletal muscle can have intrinsic spontaneous activity

A

FALSE - it has no intrinsic spontaneous activity

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15
Q

TRUE or FALSE - a single motor neuron can only stimulate itself

A

FALSE - a single motor neuron can drive the coordinated simultaneous contraction of up to thousands of neutrons

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16
Q

What is the neuromuscular junction (NMJ)?

A

the synapse between motor neurone axon terminals and a muscle fibre

17
Q

What is the active zone of the NMJ?

A

it is the release site of neurotransmitters. the active site has specialised proteins which bind to the vesicles and allow their diffusion. overall, it controls the secretion and release of vesicle.

18
Q

What is the sarcolemma of the NMJ?

A

a structure composed of in folds which increase surface area and allow for more receptors.
it also contains an important protein which breaks down Ach (AchE).

19
Q

What are the functions of vesicles?

A

They provide metabolic support and regulate neurotransmission.

20
Q

Where is there the highest density of vesicles in the NMJ?

A

Near the release site. When Ca2+ reaches the nerve terminal, the vesicles are released.

21
Q

What is the size of the NMJ’s synaptic cleft?

A

it is small, so to minimise travel distance and increase transmission speed.

22
Q

What neurotransmitter is used in the NMJ?

A

Acetylcholine (Ach)

23
Q

Transmission at the NMJ:

A
  1. action potential propagates down the the motor neuron
  2. Ach is released
  3. Muscle fiber is depolarised
  4. depolarisation triggers an action potential
  5. muscle fiber AP trigger contraction
24
Q

How is Ach synthesised?

A

Acetyl CoA + Choline via choline acetyltransferase

25
Q

How is Ach broken down?

A

via acetylcholinesterase, producing acetic acid + choline

PHSL231 (14 decks)

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