Integrated control of blood pressure

Question 1

What are baroreflexes?

Answer 1

A homeostatic mechanism that helps to maintain BP at a constant.
It adjusts cardiac output & peripheral vascular tone to stabilise arterial pressure.

Question 2

Where are the two arterial baroreceptors in the heart?

Answer 2

The aortic arch

Carotid sinus

Question 3

Where do the baroreceptors terminate?

Answer 3

At the nucleus tractus solitarus (NTS) in the medulla of the brain stem

Question 4

What are the two nerves involved in cardiac responses?

Answer 4

Vagus nerve (X) - aortic arch
Glossopharyngeal (IX) - carotid sinus

Question 5

What is the response when there is an increased MAP?

Answer 5

Increased pressure = Increased baroreceptor firing = Increased PNS(vagal) tone - stimulates the nucleus ambiguus
= increased Ach resulting in a decrease in HR

Theres a decrease in sympathetic tone - CVLM - Inhibits the RVLM = Decreased HR and TPR

Question 6

What is the response when there is a decreased MAP?

Answer 6

Decreased BR firing = Decreased PNS tone (this inhibits the nucleus ambiguus) = decreased Ach = increased HR

Increased SNS tone (stimulates RVLM) = Increased nor. adrenaline = Increased HR, TPR

Question 7

What cell bodies does the nucleus ambiguus have?

Answer 7

For the vagus

Question 8

What does the vagus innervate?

Answer 8

The pacemaker regions SAN & AVN