Normal Blood Pressure Regulation

Question 1

BP=

practical analogy

Answer 1

BP= CO x SVR

where:
CO= HR x stroke volume
SVR= 1/r^4

*to increase pressure in a hose you either have to add more volume (CO) or squeeze the hose (SVR)

Question 2

Vasodilation and vasoconstriction effect on SVR & color/temperature of extremities

Answer 2

Vasodilate–> dec. SVR—> more blood flow–> extremities warm and pink

vasoconstrict –> inc. SVR –> dec. blood flow –> extremities cool and pale

Question 3

Local regulators of vasoconstriction/vasodilation and receptors they act on

Answer 3

Endothelin: ETa receptor, vasoconstrictor
NO: no receptor, diffuses, vasodilator
adenosine: local vasodilator

Question 4

Nitroglycerin MOA

Answer 4

Breaks down into NO

• causes venodilation –> dec. preload–> dec. O2 demand
• causes coronary artery vasodilation –> inc. O2 supply

Question 5

Q (flow)=

Answer 5

Q= pressure/resistance

Question 6

Overall scheme of blood pressure control

Answer 6

Neural: SNS has efferents to heart (inc. CO), adrenal medulla (NE, Epi release), kidney (renin release) and vessel walls. Vagus innervates heart to slow it down

Humoral: kidney releases renin in response to low perfusion pressure. AngII causes vasoconstriction, the release of aldosterone (sodium reabsorption), and reabsorption of sodium directly. It also tells the hypothallamus to release ADH, and stimulate thirst.

Question 7

How do baroreceptors work? When do they fire?

Answer 7

At normal blood pressure, barareceptors fire tonically and stimulate the PNS. At low BP, firing rate decreases and SNS is stimulated

Question 8

Systemic mediators of blood pressure and receptors

-actions?

Answer 8

Norepinephrine: alpha-1 receptor on vascular smooth muscle

arginine vasopressin: V1 receptor on vascular smooth muscle

Angiotensin II: AT1 receptor on vascular smooth muscle

** all do vasconstriction AND venoconstriction**