W1, 1 Regulation Of BP (physio)

Question 1

Baroreceptors location

Answer 1

occur in the adventitia of arteries at two main locations:
1) Carotid sinus.
2) Aortic arch.

Question 2

Carotid sinus nerve joins the ………. nerve to reach the brainstem and terminate in the nucleus tractus solitarius (NTS)

Answer 2

glossopharyngeal (ninth cranial nerve)

Question 3

• Aortic baroreceptors are found mainly on the transverse arch of the aorta. Their fibers form the aortic nerve, then ascend in the …….. nerve to terminate in the nucleus tractus solitarius (NTS) of the brainstem.

Answer 3

vagus (tenth cranial nerve)

Question 4

Baroreceptors are mechanoreceptors that respond to ……….

Answer 4

• stretch (not blood flow)
  Note: A rise in arterial pressure stretches the artery wall, which deforms and excites the receptor terminals.

Question 5

Baroreceptors exhibit static and dynamic sensitivity: Arterial baroreceptors respond not only to the magnitude of the
pressure ( …a… sensitivity) but also to its rate of change ( …b… sensitivity).

Answer 5

a = static
b = dynamic

Question 6

An acute rise in arterial pressure increases the baroreceptor traffic, which is conveyed
by the vagus nerve and glossopharyngeal nerves to the brainstem, where it activates the following pathways?

Answer 6

1) A fall in sympathetic vasomotor activity causes peripheral vasodilatation, which reduces total peripheral resistance.

2) A fall in cardiac sympathetic activity and rise in vagal parasympathetic activity cause bradycardia and reduced myocardial contractility, which together reduce cardiac output.

Question 7

What is a common cause of decreased arterial blood pressure

Answer 7

Hypovolemia (it reduces the cardiac stroke volumeand arterial pulse pressure, and in severe cases it also reduces mean arterial BP.)

Question 8

The fall in baroreceptor traffic triggers the following reflex responses:

Answer 8

1) Increased cardiac sympathetic activity and reduced vagal parasympathetic activity cause a tachycardia and increased myocardial contractility. These changes help restore the depressed cardiac output.

2) Increased sympathetic vasomotor activity causes vasoconstriction of peripheral resistance vessels. The resulting rise in total peripheral resistance helps to maintain the mean arterial pressure.

Others …

Question 9

What is the major role of the baroreflex?

Answer 9

to buffer short-term fluctuations in arterial pressure leading to the short-term stabilization (homeostasis) of BP over seconds to minutes.