Hypertension: Central and Peripheral Mechanisms

Question 1

What four systems influence blood pressure?

Answer 1

1) Renal System
2) Nervous System
3) Humoral System
4) Local Vessel Level

Question 2

What is the definition of HTN?

Answer 2

Stage 1 : SBP 140-159 OR DBP 90-99

Stage 2: SBP >160 OR DBP >100

Question 3

1) What organ is primarily responsible for long-term blood pressure control?
2) What are the two mechanisms that it uses to control BP?

Answer 3

1) Kidney
2) Reduction in renal blood flow –> increased reabsorption of Na and fluid
AND
decreased pressure in renal arterioles –> renin release –> vasoconstriction and fluid retention

Question 4

What is the effect of the sympathetic and parasympathetic nervous system on the heart?

Answer 4

Sympathetic: increased CO and BP (increased contractility, vasoconstriction, increased HR)
Parasympathetic: decreased BP by decreasing HR and some vasodilation

Question 5

What mechanism is responsible for rapid moment to moment adjustments in blood pressure? How does it work?

Answer 5

Baroreceptor Reflexes
Respond to stretch or pressure on arterial walls
Increased stretch = increased firing = decreased CO and vasodilation to decreased BP

Question 6

How is the baroreceptor response changed with chronic HTN?

Answer 6

Shifts the receptor firing curve to the right = labile blood pressures and defective regulation of chronically high blood pressure
(constant firing makes it less sensitive)

Question 7

Chemoreceptors

1) what are they sensitive to?
2) when is this triggered?

Answer 7

1) sensitive to low oxygen, high CO2 and H+ excess

2) very low BP to trigger –> last ditch effort

Question 8

Atrial stretch reflex?

1) what is it sensitive to?
2) what does stimulation cause?

Answer 8

1) volume changes

2) increased HR, increased water filtration, and decreased ADH and increased ANP

Question 9

What is the vasodilator theory?

Answer 9

The greater the rate of metabolism and/or the less availability of oxygen leads to a greater formation of vasodilator substances in the tissue cells

Question 10

1) What is the effect of Magnesium?

2) What is the effect of calcium?

Answer 10

1) vasodilator

2) vasoconstrictor

Question 11

What endothelial derived factors cause relaxation?

Answer 11

Nitric Oxide, prostacyclin, EDHF, bradykinin

Question 12

What endothelial derived factors cause constriction?

Answer 12

Endothelin, thromboxane, angiotensin II

Question 13

What is the first line of treatment for hypertension?

Answer 13

Life style management:

Diet, weight reduction, reduce stress, increase exercise, stop smoking