Lecture 23

Question 1

What is the main purpose of blood pressure control?

Answer 1

To maintain homeostasis by redirecting blood flow to active tissues.

Question 2

Where are baroreceptors located?

Answer 2

In the aorta and carotid sinuses.

Question 3

How do baroreceptors respond when blood pressure falls?

Answer 3

Decrease firing → sympathetic activation → ↑HR, ↑contractility, vasoconstriction.

Question 4

How do baroreceptors respond when blood pressure rises?

Answer 4

Increase firing → parasympathetic activation → ↓HR, ↓contractility, vasodilation.

Question 5

What do chemoreceptors monitor?

Answer 5

O2, CO2, and H+ (pH) levels.

Question 6

Where are chemoreceptors located?

Answer 6

In the aortic and carotid sinuses, near baroreceptors.

Question 7

Response to ↑CO2/↑H+ (low pH)?

Answer 7

Increase CO and constrict peripheral vessels.

Question 8

Response to ↓CO2/↓H+ (high pH)?

Answer 8

Decrease CO and dilate peripheral vessels.

Question 9

What are the roles of the cardiovascular centers in the medulla?

Answer 9

Parasympathetic ↓HR/SV; Sympathetic ↑HR/SV; Vasomotor controls vessel tone.

Question 10

Which hormones regulate BP?

Answer 10

Catecholamines, ADH, renin-angiotensin-aldosterone system, ANH.

Question 11

Effects of catecholamines?

Answer 11

Increase HR, contractility, and blood flow to muscles, liver, heart.

Question 12

What does ADH do?

Answer 12

Promotes water reabsorption and increases blood volume; slight vasoconstrictor.

Question 13

What triggers renin release?

Answer 13

Decreased blood flow to the kidneys.

Question 14

What does angiotensin II do?

Answer 14

Powerful vasoconstrictor; stimulates ADH and aldosterone.

Question 15

What does aldosterone do?

Answer 15

Increases Na+ and water reabsorption, raising BP.

Question 16

What triggers thirst?

Answer 16

Increased blood osmolality detected by hypothalamic osmoreceptors.

Question 17

What does ANH do?

Answer 17

Promotes Na+/water loss and suppresses renin, aldosterone, ADH → lowers BP.

Question 18

What is autoregulation?

Answer 18

Local control of blood flow without neural or hormonal input.

Question 19

Chemical signals that dilate precapillary sphincters?

Answer 19

NO, low O2, high CO2, histamine.

Question 20

Chemical signals that constrict precapillary sphincters?

Answer 20

Endothelins, high O2, low CO2.

Question 21

What is the myogenic response?

Answer 21

Arterioles constrict when stretched (Bayliss effect) to protect tissues.

Question 22

What is the Valsalva maneuver?

Answer 22

Forced expiration against a closed glottis → ↑intrathoracic pressure → ↓venous return.

Question 23

Valsalva Phase I?

Answer 23

Onset strain → transient BP rise.

Question 24

Valsalva Phase II?

Answer 24

↓ venous return → ↓ SV → ↓ BP → ↑HR & vasoconstriction → BP recovery.

Question 25

Valsalva Phase III?

Answer 25

Release of strain → sudden BP dip.

Question 26

Valsalva Phase IV?

Answer 26

BP overshoot → baroreflex → bradycardia → normalization.