Long term control of blood pressure/hypertension

Question 1

How can hypotension be defined in general? What about hypertension? How can you get transient elevations and chronic elevations of arterial pressure?

Answer 1

Low BP of systolic less than 90; sustained elevated arterial pressure of 140/90 or greater;

transient: fever, physical exertion, emotional upset
chronic: heart failure, vascular disease, renal failure, stroke

Question 2

Define what mediates fast, intermediate, and slow changes in arterial blood pressure

Answer 2

Baroreceptor reflex: cardiac and vascular;
renal actions: PVR;
renal salt and water excretion

Question 3

What is the predominant mechanism for feedback gain at optimal pressure?

Answer 3

RAA system

Question 4

How do kidneys act directly and indirectly to maintain long-term blood pressure?

Answer 4

Direct: alter blood volume;
RAA system (JGA)

Question 5

What causes release of renin? What does angiotensin II help stimulate in terms of secretion? What does this product help with in terms of release?

Answer 5

Lowered blood pressure;
aldosterone;
ADH release

Question 6

How can the RAA system act (2 ways)?

Answer 6

Locally and globally

Question 7

What determines renin secretion?

Answer 7

1. Neural baroreceptors through renal sympathetics to granular cells in JGA
2. Intra-renal baroreceptors in aa
3. NaCl delivery to macula densa of JGA (too much would inhibit renin secretion)

Question 8

What can lead to afferent arteriole resistance going down? What can lead to efferent arteriole resistance going up? What do these both promote?

Answer 8

decreased NaCl at macula densa;
Increased renin and A II;
Increased glomerular filtration pressure

Question 9

What does A II do for PVR, GFR, and blood volume? How can it ultimately affect renin production negatively?

Answer 9

Vasoconstriction (increase PVR);
Constrict mesangial cells and reduce surface area, reducing GFR;
stimulates aldosterone secretion and prox Na-H exchange to increase blood volume;
binds on granular cells (AT-receptor) to lower IC Ca, inhibiting renin

Question 10

What in the short term maintains a BP setpoint? Long-term?

Answer 10

Baroreceptor reflex;

kidneys

Question 11

What four “organs” help maintain blood pressure?

Name the factors influencing blood pressure

Answer 11

Heart, bv’s, kidney, brain;
CO, PR, blood volume;
BP = CO x PVR = SV x HR x PVR

Question 12

What do Na and water do with respect to volume of blood and vascular system?

Answer 12

Adjust the volume of blood to fit vascular system

Question 13

What determines ECF, and how much does Na make up this substance?

Answer 13

Total osmotic content; 90%

Question 14

What is the major player in controlling Na content? What else contributes?

Answer 14

A II; some symp nerve activity, ADH, and ANP

Question 15

On graph of intake or output vs. arterial pressure, what is the 100 mm Hg mark called? What happens with e.g. increased volume or salt?

Answer 15

Equilibrium point; you have negative state where you return towards “normal”

Question 16

What is the main trigger for reduction in plasma and ECF volume?

Answer 16

Increased blood pressure and increased afferent arteriolar pressure (aim to decrease A II and later increase GFR)

Question 17

What major factor controls aldosterone? What does it help stimulate in cortical tubules and CD?

Answer 17

A II levels, with minor help from plasma K concentration and ANP;
stimulate Na reabsorption, or about 2% of total filtered sodium

Question 18

What is ultimately the result of increased renal arterial pressure and increased pressure in the glomerular capillaries on the afferent arterioles?

Answer 18

Constriction, leading to decreased renal blood flow, as well as inhibiting the increase in glomerular capillary pressure

Question 19

What do natiuretic peptides do? Examples?

What things can enhance Na reabsorption, or decrease it?

Answer 19

Inhibit release of renin, relax afferent arteriole, can help diagnose e.g. CHF;
cortisol, estrogen, GH, TH, insulin;
glucagon, progesterone, PTH

Question 20

What do baroreceptors assess? Osmoreceptors?

What two components control water excretion and how do they do it?

Answer 20

Vascular fullness vs. plasma osmolality;

proximal (regulate ECF based on BP) and distal (ADH determines)

Question 21

In the case of change in plasma volume vs decreased osmolality, which wins out?

Answer 21

Plasma volume (ie effects of baroreceptors will trounce effects of osmoreceptors since the priority is VOLUME retention)

Question 22

What is the primary determinant of long term blood pressure? How do prox nephron and distal nephron differ in their handling of salt and water? What regulates ADH secretion?

Answer 22

Sodium content via its effects on ECF volume;
affects Na and water together in prox, vs. Na by aldosterone and water by ADH in distal;
Baroreceptors vs. osmoreceptors (BP vs. plasma osmolality)

Question 23

Hypothesis for hypertension is…

Answer 23

abnormal renal sodium handling could result in HTN

Question 24

What condition can lead to hypernatremia and hypokalemia?

Answer 24

Primary hyperaldosteronism

Question 25

What can obesity lead to that would result in HTN?

Answer 25

Hyperinsulinemia (smooth muscle proliferation and vasoconstriction; kidneys with more Na reabsorption; heart with greater cardiac output due to SNS)