Neuronal communication

Question 1

Provide a short explanation for the following structural features of neurones:
- Cell body (1
- Axon (1)
- Dendron (1)

Answer 1

• Cell body; the cytoplasm (surrounding the nucleus) contains lots of mitochondria and ER for the production of neurotransmitters. (1)
• Axon; carries nervous impulse away form the cell body. (1)
• Dendron; extensions of the cell body carrying nervous impulses towards the cell body and branches into smaller fibres called dendrites. (1)

Question 2

Myelin sheaths on neurones are made up of many layers of plasma membranes. How do myelinated neurones differ from non-myelinated neurones? (3)

Answer 2

• Myelin sheath acts as an insulating later (1)
• Impulses in these neurones are transmitted much quicker (1)
• In myelinated neurones, the nerve impulse jumps from one node of Ranvier to the next/in non-myelinated neurones, the nerve impulse is transmitted continuously. (1)

Question 3

Describe the pathway of a nerve impulse starting from the stimuli. (1)

Answer 3

Stimuli -> sensory neurone -> relay neurone -> motor neurone -> effector cell (1)