Neuromuscular System ( PE paper 1 Miss Kieser)

Question 1

What are the 3 main types of muscle fibres in the body ?

Answer 1

• slow twitch muscle fibre
• Fast twitch muscle fibre type 2a
• Fast Twitch muscle fibre type 2b

Question 2

What is a slow twitch fibre ?

Answer 2

it requires aerobic respiration and is predominantly used for people competing in a marathon.

Question 3

What is fast twitch fibres 2a ?

Answer 3

requires anaerobic respiration and is predominantly used for people competing in a 1500m race

Question 4

What is fast twitch fibres 2x ?

Answer 4

requires anaerobic respiration and is predominantly used for people competing in a 100m race

Question 5

What are the characteristics of slow twitch fibres ?

Answer 5

• contraction speed is slow
• high capillary density
• fatigue levels are low

Question 6

What are the characteristics of fast twitch fibres 2a ?

Answer 6

• contraction speed is medium
• force of contraction is medium
• fatigue levels are medium

Question 7

What are the characteristics of fast twitch fibres 2x ?

Answer 7

• large motor neuron size
• force of contraction is high
• fatigue levels are high

Question 8

What is the process of a PNF stretch.

Answer 8

• Stage1:
  passive stretching with partner for 30 seconds. The muscle spindle will detect the stretch and help prevent overstretching.
• Stage 2:
  isometric contraction for 10 seconds. The Geogi tendon senses tension.
• Stage 3:
  passive stretching is repeated however stretch should go further with the help of the autogenic inhibition. This essentially tells the muscle spindle to stop working so that range of movement can increase.

Question 9

What is the all-or-none law ?

Answer 9

this is where the motor units exhibit an all-or-none response.

Question 10

How do muscle contractions occur ?

Answer 10

they occur when an electrical impulse travels down the spinal cord, along motor neurones to the muscle fibres.

Question 11

What is the role of the axon ?

Answer 11

it is responsible for carrying the electrical impulse

Question 12

What is the role of the myelin sheath ?

Answer 12

it is responsible for protecting the signal, and acts as an insulator that surrounds the axon

Question 13

What electrochemical process allows the nerve impulse to travel to the muscle fibre.

Answer 13

action potential

Question 14

What happens when the impulse travels to the end of the axon ?

Answer 14

it triggers the release of acetocholine. Acetocholine is secreted in the synapse to help the impulse to cross the gap. If enough acetocholine is present then action potential occurs and contraction of the muscle occurs.

Question 15

What is wave summation ?

Answer 15

this is the repeated activation of a motor neurone that stimulates a muscle fibre.

Question 16

What is spacial summation ?

Answer 16

this is where all motor units are stimulated at the same exact time, therefore maximal force can be applied.

Question 17

What’s a tetanic contraction ?

Answer 17

this is where stimuli are delivered at high frequency without rest, therefore muscles contracts in rapid succession .