lecture 19

Question 1

how is covid19 related to the angiotensin 2 disease state

Answer 1

SARSCoV2 spike proteins bind to target cells via angiotensin converting enz 2 > inhibition of ACE2 + decreased ACE2 expression in infected cells > higher circulating levels of Ang2

Question 2

what are the harmful effects of ang2 and how does body stop it

Answer 2

ang2 can cause damage to tissues
- in alveoli = decrease lung uptake oxygen
- in cardiac myoc = CHF
can also cause inflammation and apoptosis

stop by ACE2 break down to ang1-7 and can bind to MAS1 R to counteract harmful effects

Question 3

how does BV correlate with BP

Answer 3

= increase BV = increase pressure on walls of blood vessels
= increase BV > increase venous return to heart > increased stroke volume > increased cardiac output > increased BP

Question 4

how does increased SNS input to kidney act contribute to hypertension

Answer 4

increase SNS input to kidneys > increase renin > increase ang2 = decreased renal Na secretion = BV increases BP increases (these effects can contribute to chronic hypertension)

Question 5

what is renal SNS involvement in hypertension

Answer 5

efferent renal sns act. usually increases hypertension
- (chronic lowlevel renal nerve stim induces hypertension)
- sympatholytic drugs decrease BP

Question 6

how can the renin-angio system be manipulated to clinically decrease BP

Answer 6

inhibition via
AT1 anta
ACE inhibi
b blockers

Question 7

whats AT1 R anta clinically useful for + ex

Answer 7

useful for lowering BP
- Cozaar = angiotensin 2 R blocker (ARB)
- decrease vasocon
- decreases release of aldosterone

Question 8

whats ACE inhibitors clinically useful for + ex

Answer 8

useful for lowering BP
- inhibits ACE > deccrease amount of angiotensin 2 produced = lower BP

Question 9

whats b blocker clinically useful for + ex

Answer 9

lowering BP
- decrease ang2 production
- inhibit renin release from JG cells caused by SNS act
- b blocker decrease BP by inhibiting the blood pressure increasing effects of ang2 (vasocon + incr salt intake + increase water in)

Question 10

What is CHF

Answer 10

heart failture due to reduction of contractility of heart > decrease stroke volume > decrease BP > this decrease cardiac output causes activation of compensatory system (Vasopressin RAS SNS) and to increase fluid retention to increase volume of blood delivered to heart
- increase volume stretches muscles (result in decreasing SV and fluid accumulation in tissues)

Question 11

describe starling’s law

Answer 11

drop in BP causes increase fluid retention > increased volume of blood increases stroke volume
The greater that the heart muscle is stretched during diastole the greater the force of contraction during systole

Question 12

CHF in the right side of the heart

Answer 12

• failure of right ventricle = accumulation of blood in right heart + venous system >blood vessels accum in capillaries = weaker + fluid build up in tissue > edema (more pronounced in lower extremities due to grav)

Question 13

CHF in the left side of the heart

Answer 13

• failure of left side = accumulation of blood in pulmonary circulation > blood in lungs = cant breath

Question 14

treatments for CHF?

Answer 14

AT1 anta - decrease effects of ang2 > decrease retention of Na and water and decrease vasocon
ACE inhib - decrease production of ang2
b blockers - decrease SNS mediated production of ang2
diuretics - increase excretion of na and water by kidneys (loop stronger than thiazide)

Question 15

describe function of loops of henle, thick ascending limb, distal con tubule

Answer 15

loop of henle = sire for water reabsorption driven by hyperosmotic interstitium of renal medulla
thick ascending limb = site of Na K Cl reuptake transport
distal convoluting tub = site of na reuptake trans

Question 16

describe diuretic action in renal tub

Answer 16

• in thick ascending limb: loop diuretics inhibit the Na K Cl symporter > decreases Na absorp (normally reabsorbs 25% of Na+ load)
• in distal con tub: thiazide diuretics inhibit Na Cl transporter (normally 5%)

Question 17

the renin-angiotensin-system is antagonized by _____ peptides and released with _____

Answer 17

natriuretic peptides - increase sodium excretion and released with hypervol

Question 18

what are the 2 natriuretic peptides

Answer 18

Atrial natriuretc peptide (ANP) is produced by
smooth muscle cells in the heart atria
Brain-type natriuretic peptide (BNP) is produced
by the CNS as well as the heart ventricles

Question 19

what tissues does natriuretic peptides act on

Answer 19

vasculature (induce dilation) and kidneys (increase glomerular filtration rate, Increase excretion of sodium, Decrease release of renin)

Question 20

what are natriuretic peptides effect on vasculature

Answer 20

induce dilation
reduce calcium released from SR + reduce calcium sensitivity of contractile proteins = lower BP

Question 21

what are natriuretic peptides effect on kidney to increase filtration rate

Answer 21

• causes relaxation of glomerular cells > increases SA for filtration of blood = diuresis

Question 22

what are natriuretic peptides effect on kidney to increase sodium excretion

Answer 22

inhibit Na reabsorption in kidney tubules so inhibit Na chs = diuresis

Question 23

what are natriuretic peptides effect on kidney to decreases release of renin

Answer 23

decreases ang2 lvls > decreases aldosterone levels > decrease vasoconstriction

Question 24

whats ACE inhibitors clinically useful for + ex

Answer 24

useful for lowering BP
- inhibits ACE > decrease amount of angiotensin 2 produced = lower BP