Control Of Heart Rate (7.9)

Question 1

Describe the role of the sympathetic and parasympathetic nerves

Answer 1

Sympathetic - fight or flight response. Triggers the release of adrenaline causing an increase to heart rate and blood pressure.

Parasympathetic - responsible for rest and digest returning the body to its regular state. Saving energy, allowing digestion to occur and decreasing blood pressure and heart rate

Question 2

State the region of the brain responsible for coordinating heart rate

Answer 2

The region responsible is the cardiac control center in the medulla

Question 3

Explain the sequence of events leading to an increase in heart rate from exercise (4/5 marks)

Answer 3

As exercise increases there is an increase in CO2 concentration , H+ ions and lactic acid in the blood. These are detected by chemoreceptors in the aorta and and carotid artery.

These alert the cardiac vascular control centre in the medulla which triggers the release of more sympathetic nerve impulses to the SAN. This causes the SAN to fire more causing an increase in heart rate