Exam Question & Answer

Explain how carbon dioxide/acidity in blood increases Heart rate (4marks)

1. chemorecptors detect the acidity

2. Impulses to cardiac centre in the medulla

3. Information increases the stimulation of the sympathetic nervous system.

4. Adrenaline is produced and this increases the HR

5. Increased cardiac output and venous return

Explain how acidity in the blood causes increase breathing rate (4marks)

1. detected by chemoreceptors

2. Impluses to Resipatory Control Centre in the medulla

3. Nervous output to breathing muscles

4. Increased contraction of diaphram and intercoastal muscles