Regulation of Arterial Pressure

Question 1

MAP =

Answer 1

CO x TPR = HR x SV x TPR

2/3 (DBP) + 1/3 (SBP)

Question 2

MAP is regulated by:

Answer 2

Baroreceptors

Hormonally via RAAS

Question 3

Locations of baroreceptor reflexes (2)

Answer 3

Carotid sinus
-CN IX
-Sinus nerve of Hering
Aortic sinus
-CN X
-Aortic nerve
They lead to the: Nucleus  tractus solitarius (NTS)

Question 4

Once NTS receives info, what are the options?

Answer 4

Can have a parasympathetic response using the dorsal motor nucleus of the vagus nerve and nucleus ambiguus.
OR
Can have sympathetic response using the rostral ventrolateral medulla.

Question 5

Sympathetic influence

Answer 5

Decrease baroreceptor firing rate.
Influences heart muscles, vessels and SA node directly..
Also influences the adrenal gland.

Question 6

Receptors for constriction of arterioles and veins

Answer 6

alpha receptor

Question 7

Receptor for HR and contractility

Answer 7

beta-1

Question 8

Parasympathetic influence

Answer 8

Increased baroreceptor firing.
Decreased HR, via vagus n. to SA node.
Uses muscarinic receptors.

Question 9

Baroreceptor adaptations

Answer 9

Can change the set-point to different conditions, i.e. people with HTN, etc.

Question 10

How does RAAS control BP?

Answer 10

By adjusting BV.

Question 11

Renin

Answer 11

Enzyme from kidneys released from drop in BP.
Release is stimulated by beta-1 adrenergic receptor.
Converts angiotensin to angiotensin I.

Question 12

Juxtaglomerular cells

Answer 12

Cells that secrete renin. Found in the walls of renal affarent arterioles in response to low BP or to sympathetic stimulation.

Question 13

Angiotensin II

Answer 13

Causes the secretion of aldosterone from adrenal cortex.
Leads to Na and H2O retention by kidneys.
Increases BV, preload, SV, CO, BP.
Reduces urine production.

Question 14

Vasopressin

Answer 14

Acts on V1 receptors on SM and V2 receptors on collecting ducts in kidneys.

Question 15

Vasopressin is released in response to (3):

What is the goal?

Answer 15

Angiotensin II
Atrial receptors in presence of low preload.
Increased osmolarity.

To increase TPR and water retention.

Question 16

Natriuretic preload (AND, BNP, CNP)

Answer 16

Secreted by excessive preload of atria and ventricles.
Decreases TPR.
Increases fluid loss.
Inhibits renin.
Protects against overdilation or overstretching of cardiac chambers.

Question 17

Effects of changes in posture

Answer 17

Initially, MAP decreases along with all else.

However, there is an initial compensation the other way