Physiology and Action Potential

Question 1

Steps 1 and 2 of muscle fiber contraction is ____.

Answer 1

activation

Question 2

Where do steps 1 and 2 take place?

Answer 2

At the neuromuscular junction

Question 3

Steps 3 and 4 of muscle fiber contraction are called ___________

Answer 3

excitation - contraction coupling

Question 4

What do steps 3 and 4 do?

Answer 4

link the electrical signal to contraction

Question 5

Steps 1 and 2: Activation must

Answer 5

• must be a nervous system stimulation

- must generate action potential to sarcolemma

Question 6

Steps 3 and 4: Excitation-contraction coupling is

Answer 6

• action potential propogated along sarcolemma

- intracellular Ca2+ levels must rise briefly

Question 7

Phase 1, step 1?

Answer 7

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

Question 8

Phase 1, step 2?

Answer 8

ACh released; binds to receptors on sarcolemma

Question 9

Phase 1, step 3?

Answer 9

Ion permeability of sarcolemma changes

Question 10

Phase 1, step 4?

Answer 10

Local change in membrane voltage (depolarization) occurs

Question 11

Phase 1, step 5?

Answer 11

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

Question 12

Phase 2, step 1?

Answer 12

AP travels across the entire sarcolemma

Question 13

Phase 2, step 2?

Answer 13

AP travels across the entire sarcolemma

Question 14

Phase 2, step 3?

Answer 14

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

Question 15

Phase 2, step 4?

Answer 15

Myosin heads bind to actin; contraction begins

Question 16

The nerve cells that activate skeletal muscle fibers is called

Answer 16

somatic motor neurons

Question 17

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.

Answer 17

axons

Question 18

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.

Answer 18

neuromuscular junction

Question 19

What is another name for neuromuscular junction?

Answer 19

end plate

Question 20

Integral proteins are found

Answer 20

In between the opening of the sarcomere’s triad

Question 21

Integral proteins are responsible for the

Answer 21

release of calcium

Question 22

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

Answer 22

Calcium ions

Question 23

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

Answer 23

Excitation-contraction coupling

Question 24

What starts the excitation-contraction coupling process?

Answer 24

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

Question 25

What is released at the neuromuscular junction to create excitation?

Answer 25

Acetylcholine

Question 26

What does the Acetylcholine bind to?

Answer 26

Binds to receptor proteins in the sarcolemma and triggers an action potential in a muscle fiber.