Muscle Fibre Recruitment

Question 1

What happens if one motor neuron is stimulated?

Answer 1

Causes all the muscle fibres in that unit to contract

Question 2

Why does the type of activity determine what motor neurons are recruited?

Answer 2

• sprinting = motor units with fast twitch will be recruited
• jogging = motor units with slow twice fibres with be recruited

Question 3

What is the process of contraction?

Answer 3

1) nerves impulses are sent from the brain
2) travels along nerves to the motor unit and along the motor neuron
3) acetylcholine is then released
4) depolarization begins at the muscle cell adjacent to the motor end plate
5) if sufficient DP takes place, action potential is sent to muscle fibre for calcium ions to be released
5) the sliding filament theory takes place

Question 4

What is a motor unit?

Answer 4

The motor neuron and the muscle fibres associated with it (only one type of muscle fibre)

Question 5

What is the all or none law?

Answer 5

Muscle fibres can’t partially contract. If the depolarisation is great enough it will break the threshold and contraction will take place. If its not great enough the muscles won’t contract

Question 6

What is spatial summation?

Answer 6

Different activities require different strengths of muscle contraction. If the contraction is large the more motor units used and the bigger sort of motor units used. (Size and amount)

Question 7

What is wave summation?

Answer 7

Where is second impulse is received prior to the first one finishing. This is larger contraction as the second stimulus is added to the first.

Question 8

What is tetanic contraction

Answer 8

Maximal contraction of a muscle that happens through multiple impulses received