Topic 6: Organisms respond to changes in their internal and external environments

Question 1

Exercise causes an increase in heart rate.
Describe the role of receptors and of the nervous system in this process. (4 marks)

Answer 1

1. Chemoreceptors detect increased CO₂ (or lowered pH).
2. Impulse sent to medulla oblongata.
3. Medulla sends impulses via sympathetic pathway.
4. SAN increases heart rate.

Question 2

Name three structures in the Parcinian Corpuscle

Answer 2

Capsule
Axon
Mylein Sheath