Neuromuscular System - A.A&P

Question 1

What are the 3 main types of muscle fibres?

Answer 1

1. Slow Oxidative (type 1)
2. Fast Oxidative Glycolytic (type 2 a)
3. Fast Glycolytic (type 2x)

Question 2

What are some characteristics of type 1/slow muscle fibres?
Is it functional or structural?

Answer 2

• Slower contraction speed (F)
• Low intensity exercise
• ATP mainly produced aerobically
• High myoglobin content (S)
• Small motor neurone size (S)

Question 3

What are some characteristics of type 2/fast muscle fibres?
Is it functional or structural?

Answer 3

• Fast contraction speed (F)
• Fatigue quickly –> short, intense exercise
• ATP mainly produced anaerobically
• Medium/Low myoglobin content (S)
• Large motor neurone size (S)

Question 3

How do type 2a and 2x fibres differ?

Answer 3

Fast oxidative glycolytic fibres are more resistant to fatigue. Used for 1500m.
Fast glycolytic fibres fatigue quicker. Used for highly explosive events like 100m.

Question 3

How to increase the strength of contraction?

Answer 3

1. Wave Summation
2. Spatial Summation

Question 3

What is wave summation?

Answer 3

Greater the frequency of stimuli = greater tension.
More repeated actions of motor neurone = no time to relax = sustained contraction.

Question 4

What is calcium’s role in wave summation?

Answer 4

Calcium needed for muscle to contract.
Repeated nerve impulses with no time to relax = calcium builds up.
Produces tetanic contraction - powerful, sustained and smooth contraction.

Question 5

What is spatial summation?

Answer 5

Altering number and size of muscle’s motor units –> allows some fibres to relax while others are contracting.

e..g, floor routine in gymnastics - after many jumps, more dance type moves to allow type 2 fibres in legs to relax for next jumps.

Question 6

What does a motor unit consist of?

Answer 6

A motor neurone and muscle fibre.

Question 7

What do motor neurones and fibres do? Link.

Answer 7

Motor neurones connect the nervous system to the muscle fibres = contraction.

Question 8

What is the neuromuscular junction?

Answer 8

Where the motor neurone and muscle fibre meet.

Question 9

What is the all or none law?

Answer 9

For muscles to contract, all of the fibres in a motor unit must be stimulated.
Won’t work if it only partially contracts.

Question 10

What is the ‘threshold’ in the all or none law?

Answer 10

The minimum amount of stimulation is the threshold.
Meets to or more than threshold = contraction.

Question 11

What does PNF stand for? What is it?

Answer 11

Proprioceptive neuromuscular facilitation.
A stretching technique to improve range of motion.

Question 12

What are muscle spindles? Function in PNF.

Answer 12

Proprioceptors that detect how far and fast a muscle is being stretched.
Sends excitatory signal to CNS –> impulse back to muscle –> telling it to contract = stretch reflex.
Contraction to prevent over-stretching.

Question 13

Where are golgi tendon organs found? Function in PNF.

Answer 13

Found between the muscle fibre and tendon.
Detect levels of tension in a muscle.

When isometric contraction occurs, they sense the increase in muscle tension –> sends inhibitory signals to brain = delays stretch reflex.

Question 14

What is autogenic inhibition?

Answer 14

After golgi tendon organs delay the stretch reflex.
The antagonist muscle relaxes and lengthen –> to produce greater range of movement.