Nervous System - Practice Questions

Question 1

Explain how the transmission of a nerve impulse along a fibre that is myelinated differed from one that is unmyelinated. (2 marks)

Answer 1

• unmyelinated: impulse travels along the whole membrane

- myelinated: undergoes saltatory conduction, jumps from node to node, is faster

Question 2

Define refractory period. (2 marks)

Answer 2

• when a nerve fibre cannot be stimulated again

Question 3

Action potentials are describes as all or none responses. However, it is possible for you to detect the difference between a sheet of paper and a brick being dropped on you foot. Explain why. (3 marks)

Answer 3

• action potential remains the same
• more action potentials are created in a time frame
• cerebrum processes the increased number of action potentials and the person feels more pain

Question 4

State a reason why reflex arcs are so important. (1 mark)

Answer 4

• prevents further damage to tissues

Question 5

Where are nerve cells that detect pain located? (2 marks)

Answer 5

• skin

- receptors for pain are at the ends of sensory neurons

Question 6

Describe how a nerve impulse is propagated along a myelinated fibre. (4 marks)

Answer 6

• depolarisation occurs at Nodes of Ranvier along fibre
• sodium channels open for sodium ions to diffuse into axon cytoplasm
• depolarisation occurs and potassium channels open for potassium ions to diffuse out across membrane
• inside of membrane becomes negative in relation to outside

Question 7

Explain how nerve impulses can travel from one neuron to the next. (3 marks)

Answer 7

• exocytosis of neurotransmitters from vesicles
• diffusion of neurotransmitter across synapse
• neurotransmitters bind to specific receptors on dendrite of next neuron

Question 8

Why is it important for pain receptors to be located,in their position? (3 marks)

Answer 8

• close to the surface of the skin
• can detect small changes in temperature/pressure quickly
• rapid detection helps protect body

Question 9

What part of the brain is effected when someone has a limited perception to pain? (2 marks)

Answer 9

• cerebral cortex

- several parts of the cerebral cortex receive information from pain receptors

Question 10

Explain why reflex arcs have very few synapses (2 marks)

Answer 10

• info passes across synapses slowly compared to axon

- fewer synapses, less time taken to respond