CB34&35: Muscle contraction

Question 1

What is the muscle motor unit?

Answer 1

The motor neurone, its axon,, branches and the muscle fibres it innervates.

Question 2

What happens when a muscle is under-stretched?

Answer 2

The muscle can’t contract anymore because the actin and myosin filaments are already too close together.

Question 3

What happens when a muscle is over-stretched?

Answer 3

The muscle can’t contract because the actin and myosin filaments are too far to reach each other.

Question 4

What connects the motor neurone and the muscle?

Answer 4

The neuromuscular junction

Question 5

How is the action potential relayed through the muscle cell?

Answer 5

Thanks to the T-tubules

Question 6

Where are T-tubules found?

Answer 6

They associate with the sarcoplasmic reticulum forming triads near actin filaments.

Question 7

What does the action potential arriving in the muscle cell lead to?

Answer 7

Release of Ca2+ from sarcoplasmic reticulum