Control of blood pressure

Question 1

Why does arterial blood pressure need to be kept relatively constant?

Answer 1

too low- organs would fail since not enough force to pump blood to tissues which need it
too high- damage vessels and organs, damage capillaries which are not designed to withstand such high pressures

Question 2

what is the relationship for mean arterial blood pressure?

Answer 2

MABP= total peripheral resistance x cardiac output

Question 3

what are the 2 types of baroreceptor ?

Answer 3

• arterial

- cardio pulmonary

Question 4

where are the 2 types of arterial baroreceptors located? which nerve do they follow?

Answer 4

• carotid bodies near chemoreceptors follow glossalpharyngeal nerve to cardiac control centre
• aortic baroreceptors following vagus nerve back to brainstem and medulla

Question 5

how do baroreceptors detect changes in pressure?

Answer 5

they are stretch receptors

Question 6

how do baroreceptors detect changes in blood pressure?

Answer 6

they are always firing at a set level hence they can detect when the blood pressure goes above or below this normal

Question 7

how do cardio pulmonary baroreceptors function?

Answer 7

operate at a low pressure and sense the central blood volume

Question 8

where are cardio pulmonary receptors located?

Answer 8

in the pulmonary system in the right atria or ventricles

Question 9

what is the response if there is a decrease in firing of the cardio pulmonary receptors?

Answer 9

sympathetic nerve activity to the heart and vessels increase and parasympathetic nerve activity to the heart decreases

Question 10

wha do cardio pulmonary baroreceptors predominantly measure?

Answer 10

changes in blood volume

Question 11

what is the bainbridge response reflex

Answer 11

sympathetic mediated reflex in response to increase in blood volume in the atria detected by stretch leading to increased heart rate and contractility causing increase in cardiac output preventing damming of blood in veins

Question 12

What is the lateral portion if the medullary cardiovascular control centre responsible for?

Answer 12

efferent sympathetic nerves which increase the contraction of blood vessels and increase heart rate and contractility

Question 13

what is the medial portion of the medullary cardiovascular control centre responsible for?

Answer 13

efferent parasympathetic (vagal) nerves involved in regulation of the heart

Question 14

which nerves predominantly control tone at rest?

Answer 14

parasympathetic

Question 15

what features of the cardiovascular system do sympathetic nerves have significant control of?

Answer 15

stroke volume and heart rate

Question 16

how are veins affected by the sympathetic nervous system?

Answer 16

decrease the capacitance of veins hence increasing the venous return and therefore the cardiac output

Question 17

what is the effect of the sympathetic nervous on the adrenal gland?

Answer 17

has innervation on the adrenal gland the circulating levels of adrenaline which affects heart and stroke volume, venous return and peripheral resistance

Question 18

how do organs auto regulate blood flow?

Answer 18

• reactive and active hyperemia

- independent of innervation and hormonal control

Question 19

what is myogenic theory?

Answer 19

stretch induced vascular depolarisation of smooth muscle due to increased arterial blood pressure

Question 20

what is metabolic theory?

Answer 20

increased arterial pressure increases oxygen washing out local factors