The Neuromuscular System

Question 1

What are the main types of muscle fibre ?

Answer 1

Slow oxidative (type 1)
Fast oxidative (type 2a)
Fast glycolytic (type 2b)

Question 2

What is the function and characteristics of type 1 muscle fibres ?

Answer 2

These fibres have slower contraction speeds and are better adapted to low intensity exercises such as long distance running
They produce most of their energy aerobically and therefore have specific characteristics that allow them to use oxygen more efficiently
Take longer to fatigue

Question 3

Characteristics of fast twitch fibres

Answer 3

Have a much faster contraction speed and can generate a greater force of contraction
Fatigue very quickly and are used for short intense bursts of effort
Produce most of their energy anaerobically

Type 2a - These fibres are more resistant to fatigue and are used for events such as the 1500m in athletics where longer bursts of energy are needed

Type 2b - These fibres fatigue much quicker than type 2a and are used for highly explosive events such as the 100m or weightlifting where quick short bursts of energy are needed

Question 4

Definition of aerobic

Answer 4

Means with oxygen and refers to exercise that is low to medium intensity where the oxygen demand of muscles can be met

Question 5

Definition of anaerobic

Answer 5

Means without oxygen and refers to exercise at high intensity such as sprinting, where the demand for oxygen by the muscles is so high that it cannot be met

Question 6

Definition of hypertrophy

Answer 6

Where the muscle has become bigger and stronger

Question 7

How does a motor neurone work

Answer 7

The motor neurone transmits a nerve impulse to each muscle fibre. Each motor neurone has branches that end in the neuromuscular junction on the muscle fibre causing them to contract when the impulse is reached

Question 8

Definition of a motor unit

Answer 8

A motor neurone and it’s muscle fibres

Question 9

Definition of a motor neurone

Answer 9

Nerve cells which transmit the brains instructions as electrical impulses to the muscles

Question 10

Definition of neuromuscular junction

Answer 10

Where the motor neurone and the muscle fibre meet

Question 11

Definition of the all or none law

Answer 11

Where a sequence of impulses has the be sufficient intensity to stimulate all of the muscle fibres in a motor unit in order for them to contract. If not none of them contract

Question 12

Definition of wave summation

Answer 12

Where there is a repeated nerve impulse with no time to relax so a smooth, sustained muscle contraction occurs rather than twitches. This is because each time a nerve impulse is sent calcium is released, over time this calcium builds up resulting in a larger contraction

Question 13

Definition of tetanic contraction

Answer 13

A sustained muscle contraction caused by a series of fast repeating stimuli

Question 14

Definition of spatial summation

Answer 14

When the strength of a contraction changes by altering the number and size of the muscles motor units

Question 15

What are muscle spindles

Answer 15

These detect how far and how fast a muscle is being stretched and produce the stretch reflex

Question 16

What are Golgi tendons

Answer 16

These detect tension in the muscle. They then send a message to the brain which allows the antagonist muscle to relax and lengthen

Question 17

How would PNF be put into practise

Answer 17

a) The individual performs a passive stretch with help of a partner. The partner should extend the leg until tension is felt by the muscle spindles at which point a stretch reflex should occur

b) The individual then isometrically contract the muscle for 10 seconds by pushing their leg again their partner who should supply just enough resistance to hold the leg in place

c) As the leg is lifted again, the Golgi tendons are responsible for the antagonist muscle relaxing, which means the leg is stretched further