Topic 4

Question 1

Label a diagram of a motor
unit

Answer 1

Limit to:
7 marks
* dendrite
* cell body
* nucleus
* axon
* motor end plate
* synapse
* muscle

Question 2

Explain the role of
neurotransmitters in
stimulating skeletal muscle
contraction

Answer 2

Limit to acetylcholine and cholinesterase.

When a nerve action potential arrives at a motor end plate, Acetylcholine (Ach) is released from the synaptic knobs and diffuses across the synaptic cleft to bind with post-synaptic receptors. This takes approximately 0.5 milliseconds to complete and is followed by a muscle action potential which is required to initiate muscular contraction.

Once the nerve action potential is completed, Cholinesterase is released.
This enzyme is responsible for the hydrolysis of acetylcholine into choline and acetic acid, clearing the synaptic cleft in readiness for the next impulse.
This is necessary in order to avoid continuous synaptic transmission.

Question 3

Explain how skeletal muscle
contracts by the sliding
filament theory

Answer 3

Include the terms:
* myofibril
* myofilament
* sarcomere
* actin
* myosin
* H zone
* A band
* Z line
* tropomyosin
* troponin
* sarcoplasmic reticulum
* calcium ions
* ATP.
Aim 7: Various online muscle contraction
simulations are available

Question 4

Explain how slow and fast
twitch fibre types differ in
structure and function

Answer 4

Limit fibre types to slow twitch (type I) and fast
twitch (type IIa and type IIb).
Type IIa and IIb are high in glycogen content
depending on training status.
Aim 8: Implications of invasive techniques for
taking samples, such as muscle biopsies.
Aim 9: Implications of drawing conclusions from
indirect measurements.

Question 5

Outline the types of
movement of synovial joints

Question 6

Outline the types of muscle
contraction

Question 7

Explain the concept of
reciprocal inhibition

Question 8

Analyse movements in
relation to joint action and
muscle contraction

Question 9

Explain delayed onset
muscle soreness (DOMS)
in relation to eccentric
and concentric muscle
contractions

Question 10

Define the terms force,
speed, velocity, displacement,
acceleration, momentum and
impulse

Question 11

Analyse velocity–time,
distance–time and force–
time graphs of sporting
actions

Question 12

Define the term centre of
mass

Question 13

Explain that a change
in body position during
sporting activities can
change the position of the
centre of mass

Question 14

Distinguish between first,
second and third class levers

Question 15

Label anatomical
representations of levers

Question 16

Define Newton’s three laws
of motion.

Question 17

Explain how Newton’s three
laws of motion apply to
sporting activities

Question 18

State the relationship
between angular
momentum, moment of
inertia and angular velocity

Question 19

Explain the concept of
angular momentum in
relation to sporting activities

Question 20

Explain the factors that
affect projectile motion at
take-off or release

Question 21

Outline the Bernoulli
principle with respect to
projectile motion in sporting
activities