muscular contractions

Question 1

What are motor units?

Answer 1

Made up of a motor neuron and a group of muscle fibres.

Question 2

What is a neurone?

Answer 2

A type of nerve cell.

Question 3

What is an axon?

Answer 3

Carries the action potential from the cell body to the neuromuscular junction.

Question 4

What is a synapse?

Answer 4

The tiny gap between the terminal end of the axon and the muscle surface where information is transmitted from one neuron to the next

Question 5

What is the neuromuscular junction?

Answer 5

The point where the motor neuron meets the muscle fibre.

Question 6

What is acetylcholine?

Answer 6

the neurotransmitter released at the neuromuscular junction and diffuses across the synapse

Question 7

What is the all or none law?

Answer 7

A motor unit contracts fully or not at all.

Question 8

What happens when we increase or decrease the rate of stimulation?

Answer 8

We get an increase or decrease in contractile strength.

Question 9

What is resting potential?

Answer 9

Where there is a lower charge inside the neurone than outside the neurone.

Question 10

What is action potential?

Answer 10

The electrical impulse carried down the axon.

Question 11

What is a neurotransmitter?

Answer 11

Chemical transmitters which diffuse across a synapse to initiate muscular contraction.

Question 12

Steps to answer a motor unit question

Answer 12

1. the nerve sends an impulse from the CNS which travel down the axon
2. when action potential is reached…
3. ACh is secreted at the neuromuscular junction
4. the impulse crosses the synapse
5. if the action potential is above the threshold…
6. the all or none law is applied

Question 13

What type of activity are type I (SO) fibres used for?

Answer 13

Endurance eg. marathon, road cycling

Question 14

What type of activity are type IIa (FOG) fibres used for?

Answer 14

Games players eg. hockey, football

Question 15

What type of activity are type IIb/x (FG) fibres used for?

Answer 15

Power events eg. javelin, 100m sprint

Question 16

Name five structural features of type I fibres

Answer 16

size: small
colour: red
mitochondria: many
glycogen store: low
capillaries: high

Question 17

Name five structural features of type IIa fibres

Answer 17

size: intermediate
colour: pink
mitochondria: some
glycogen store: intermediate
capillaries: intermediate

Question 18

Name five structural features of type IIb/x fibres

Answer 18

Size: large
colour: white
mitochondria: few
glycogen store: high
capillaries: low

Question 19

Name three functional features of type I fibres

Answer 19

Contractile speed: low
contractile force: low
Fatigue resistance: high

Question 20

Name three functional features of type IIa fibres

Answer 20

Contractile speed: intermediate
contractile force: intermediate
Fatigue resistance: intermediate

Question 21

Name three functional features of type IIb/x fibres

Answer 21

Contractile speed: high
contractile force: high
Fatigue resistance: low

Question 22

What do we mean by the term twitch?

Answer 22

A single contraction

Question 23

What is the purpose of mitochondria?

Answer 23

Produces energy in the presence of O2

Question 24

What does a high number of capillaries indicate?

Answer 24

The performer is and aerobic athlete

Question 25

What is the purpose of a high glycogen store?

Answer 25

It can be broken down very quickly to produce anaerobic energy

Question 26

Which type of muscle fibre would a long distance rower primarily use and why?

Answer 26

Fast Oxidative Glycolytic and mainly aerobic respiration therefore they will produce a large force quickly and have the capacity to resist fatigue

Question 27

Which type of muscle fibre would a triathlete primarily use and why?

Answer 27

Slow Oxidative and aerobic respiration therefore they will produce a slow force of contraction for long periods

Question 28

Which type of muscle fibre would a high jumper primarily use and why?

Answer 28

Fast glycolytic and mainly anaerobic respiration therefore they will produce maximal force