Lecture 28 10/24/23

Question 1

How does blood pressure relate to cardiac output and systemic vascular resistance?

Answer 1

BP = CO x SVR

Question 2

What are the characteristics of baroreceptors?

Answer 2

-found within carotid sinus and aortic arch
-respond to vessel distention/increases in BP

Question 3

What type of control does the arterial baroreflex have over BP?

Answer 3

short term

Question 4

What is the result of baroreceptor activation?

Answer 4

-decrease in heart rate
-vasodilation

Question 5

Why is the arterial baroreflex only involved in short term BP control?

Answer 5

-sustained increases in BP “resent” the baroreceptors
-baroreceptors become used to long term higher pressure and no longer correct it

Question 6

What things are able to stimulate the excitatory chemoreceptor reflex?

Answer 6

-low O2
-high CO2
-low pH

Question 7

What is the result of excitatory chemoreceptor reflex stimulation?

Answer 7

-increase in sympathetic tone
-increase in arterial pressure

Question 8

When is the excitatory chemoreceptor reflex most important/relevant?

Answer 8

-at lower BP
-during disease states

Question 9

What are the characteristics of autonomic control of vascular resistance?

Answer 9

-CNS vasomotor center
-afferents from baroreceptors, chemoreceptors, and metaboreceptors

Question 10

How do metaboreceptors work?

Answer 10

-metabolites build up when CO is inadequate
-metaboreceptors sense metabolites
-contractility and heart rate are increased

Question 11

What are the important receptors for autonomic control of vascular resistance?

Answer 11

-alpha 1: vasoconstriction
-beta 2: vasodilation

Question 12

Where are alpha receptors found?

Answer 12

-GI
-skin
-kidneys
(tissues that can have blood diverted away during fight or flight)

Question 13

What occurs as a result of beta-1 receptor stimulation?

Answer 13

-increased contractility
-increased heart rate
-increased rate of myocardial relaxation

Question 14

What is the Cushing’s response?

Answer 14

-reflex-mediated increase in systemic arterial pressure
-occurs as a result of increased CNS pressure

Question 15

Which system has long term control over BP?

Answer 15

renin-angiotensin-aldosterone system

Question 16

What is the stimuli for renin release?

Answer 16

diminished cardiac performance
-renal hypotension
-beta-adrenergic activation
-decreased renal sodium delivery

Question 17

Where in the kidney is diminished cardiac performance sensed?

Answer 17

juxtaglomerular apparatus

Question 18

What are the main things caused by angiotensin II?

Answer 18

-vasoconstriction
-aldosterone release -> sodium/water retention

Question 19

Why is water retention necessary during diminished cardiac performance?

Answer 19

water retention leads to increased intravascular volume, which increases venous return and CO

Question 20

How are extracellular fluid volume (ECF) and BP related?

Answer 20

increase in extracellular fluid volume = increase in systemic arterial BP

Question 21

What is the most important determinant of extracellular fluid volume?

Answer 21

sodium

Question 22

What determines ECF?

Answer 22

-dietary intake of sodium and water
-renal excretion

Question 23

What is pressure diuresis?

Answer 23

-increase in ECF causes an increase in CO and arterial BP
-increase in renal loss of water and sodium

Question 24

What are the characteristics of natriuretic peptides?

Answer 24

-cause natriuresis and vasodilation
-come from the atria and ventricles
-stimulus for release is increased wall tension/cardiac stretch

Question 25

What is a rise in B-type natriuretic peptide (BNP) associated with?

Answer 25

-increases in ventricular filling pressures
-congestive heart failure

Question 26

What local factors can have a long term effect on BP, especially in disease states?

Answer 26

-nitric oxide
-endothelin
-adenosine
-angiotensin II