Physiology and Action Potential Flashcards

1
Q

Steps 1 and 2 of muscle fiber contraction is ____.

A

activation

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2
Q

Where do steps 1 and 2 take place?

A

At the neuromuscular junction

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3
Q

Steps 3 and 4 of muscle fiber contraction are called ___________

A

excitation - contraction coupling

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4
Q

What do steps 3 and 4 do?

A

link the electrical signal to contraction

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5
Q

Steps 1 and 2: Activation must

A
  • must be a nervous system stimulation

- must generate action potential to sarcolemma

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6
Q

Steps 3 and 4: Excitation-contraction coupling is

A
  • action potential propogated along sarcolemma

- intracellular Ca2+ levels must rise briefly

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7
Q

Phase 1, step 1?

A

Action potential (AP) arrives at axon terminal at neuromuscular junction

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8
Q

Phase 1, step 2?

A

ACh released; binds to receptors on sarcolemma

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9
Q

Phase 1, step 3?

A

Ion permeability of sarcolemma changes

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10
Q

Phase 1, step 4?

A

Local change in membrane voltage (depolarization) occurs

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11
Q

Phase 1, step 5?

A

Local depolarization (end plate) potential) ignites AP in sarcolemma

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12
Q

Phase 2, step 1?

A

AP travels across the entire sarcolemma

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13
Q

Phase 2, step 2?

A

AP travels across the entire sarcolemma

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14
Q

Phase 2, step 3?

A

SR releases Ca2+; Ca2+ binds to troponin; myosin-binding sites (active sites) on actin exposed

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15
Q

Phase 2, step 4?

A

Myosin heads bind to actin; contraction begins

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16
Q

The nerve cells that activate skeletal muscle fibers is called

A

somatic motor neurons

17
Q

Somatic motor neurons reside in the brain and spinal cord, but their long threadlike extensions called ___ travel, bundled within nerves, to the muscle cells they serve to stimulate.

18
Q

Each axon forms several brances as it enters the muscle. Each axon nerve ending gives off several short, curling brances that collectively form an elliptical ___ ___, or end plate, with a single muscle fiber.

A

neuromuscular junction

19
Q

What is another name for neuromuscular junction?

20
Q

Integral proteins are found

A

In between the opening of the sarcomere’s triad

21
Q

Integral proteins are responsible for the

A

release of calcium

22
Q

What is responsible for the coupling of excitation to the contraction of skeletal muscle fibers?

A

Calcium ions

23
Q

The sequence of events by which transmission of an action potential along the sarcolemma which then leads to the sliding of myofilaments is called

A

Excitation-contraction coupling

24
Q

What starts the excitation-contraction coupling process?

A

The events at the neuromuscular junction set the stage for E-C coupling by providing excitation.

25
What is released at the neuromuscular junction to create excitation?
Acetylcholine
26
What does the Acetylcholine bind to?
Binds to receptor proteins in the sarcolemma and triggers an action potential in a muscle fiber.