Unit 2, L17 Hormonal Regulation of Body Salts

Question 1

Why do your kidneys care about Na

Answer 1

Na is the major cation of the ECF compartment, which consists of plasma and interstitial fluid
Amount of Na in ECF determines the ECV volume, which in turn determines plasma volume, blood volume, and blood pressure

Question 2

Positive Na balance

Answer 2

Na intake > Na excretion

Extra Na retained in body, leads to increased ECF volume, leads to increased blood volume, leads to increased arterial presure, leads to increased body weight (edema)

Question 3

Negative Na balance

Answer 3

Na intake < Na excretion

Decreased ECF volume, leads to decreased blood volume, leads to decreased arterial pressure

Question 4

ECV definition

Answer 4

Portion of ECF volume within the vascular system that is effectively perfusing the tissues

Question 5

Relationship between ECV and AP and CO

Answer 5

Decreased ECF means decreased vascular volume, which means decreased AP, or decreased CO is sensed as decreased ECV

Vice versa for increased ECF

Question 6

Low pressure senor for monitoring ECV

Answer 6

Increase stretch of cardiac atria, leads to increase in ANP, leads to increase Na excretion

Question 7

High pressure sensors for monitoring ECV

Answer 7

Increase pressure at aortic arch and increase pressure in carotid sinus baroreceptors leads to decrease in symp and ADH

Slow tubular flow leads to stimulation of JGA, which increases renin

Question 8

Efferent responses to monitoring ECV

Answer 8

Neurohormonal: RAAS, SNS/catecholamines, ANP, BNP, and prostaglandins

Hemodynamic: GFR and peritubular forces

Question 9

MD senses what?

Answer 9

Flow AND salt content in the lumen, gives TG feedback

Question 10

If tubular flow and Na content is high, what will that cause

Answer 10

Contraction of afferent arterioles

Decreases GFR, maintains normal filtered load. Additionally, decreases renal secretion, allows for more Na excretion

Question 11

If there is low flow and low salt, what will that produce

Answer 11

Prostaglanins and NO being released. This increases GFR to maintain normal filtered load, and increases renin secretion, conserves Na

Question 12

Renin is produced by

Answer 12

JGA

Question 13

High Na diet does what to renin

Answer 13

Suppresses secretion

Question 14

Low Na diet does what to renin

Answer 14

Increases renin secretion

Question 15

Renin is secreted by what

Answer 15

Granular JG cells on afferent arteriole just before the glomerulus

Question 16

MD will control renin production how

Answer 16

Release of ATP from MD causes vasoconstriction of afferent arteriole, so that will reduce amount of renin being produced and prostaglandins will cause an increase in renin from JG cells

Question 17

Pressure of afferent arterioles will control renin production how

Answer 17

Intrarenal baroreceptors within the JG cells, they can sense a low pressure

Question 18

How does symp nerve activity control renin production

Answer 18

Acts on JG cells via Beta 1 receptors on JG cells to produce renin

Question 19

ANG II will promote the production of

Answer 19

ADH

Question 20

Renin converts _____ to _____

Answer 20

Angiotensinogen to ANG I

Question 21

ACE converts _____ to _____

Answer 21

ANG I to ANG II

Question 22

ANG II stimulates _____ release from adrenal cortex

Answer 22

Aldosteronme

Question 23

Function of adolsterone

Answer 23

Aldosterone circulates to the kidney (DT and CD), where it increases Na/K/ATPase activity, which increases Na reabsorption and K secretion and excretion

Increased Na reabsorption leads to increase water reabsorption, if ADH is present

Question 24

ANG II function with arterioles

Answer 24

Constricts BOTH arterioles but has a greater effect on efferent, resulting in increase in GFR

Question 25

ANP is synthesized and released from

Answer 25

Cardiac atria

Question 26

Increase ANP leads to

Answer 26

Decrease symp activity, leading to vasodilation of afferent arterioles and vasoconstriction of efferent arterioles, leading to increase GFR, and increased tubular load Na, which leads to decreased Na reabsorption and increased Na excretion

Question 27

Natriuretic peptides on the tubules

Answer 27

Inhibits release of renin
Inhibits the action of ANG II
Specifically acts in medullary collecting duct to inhibit Na absorption
Overall result is salt wasting

Question 28

Increased Na+ intake leads to what for symp activity

Answer 28

Decreased symp activity, which increases GFR through dilation of afferent arterioles, decreases Na reabsorption in the proximal tubules, and increases overall Na excretion

Question 29

Increased Na+ intake leads to what for ANP

Answer 29

Increases ANP release, which increases GFR through constriction of efferent arterioles, this decreases Na reabsorption in the collecting ducts, and gives overall Na excretion increase

Question 30

Increased Na+ intake leads to what for RAAS

Answer 30

Decreases RAAS, so decreases Na reabsorption in the proximal tubule and collecting ducts, overall Na excretion increase

Question 31

Increased Na+ intake leads to what for oncotic pressure

Answer 31

Decreases oncotic pressure, decreases Na reabsorption in the proximal tubule, and increases overall Na excretion

Question 32

Decreased Na+ intake leads to what for symp activity

Answer 32

Increased symp activity leads to constriction of afferent arterioles, decreases GFR. Leads to overall increase in Na reabsorption in the proximal tubule, decreasing overall Na excretion

Question 33

Decreased Na+ intake leads to what for ANP

Answer 33

Decreased ANP leads to dilation of efferent arterioles and decreased GFR, increasing Na reabsorption in the collecting ducts and decreasing overall Na excretion

Question 34

Decreased Na+ intake leads to what for RAAS

Answer 34

Increased RAAS increases renin, through MD sensing it, to increase Na reabsorption in the proximal tubule and collecting ducts.

Question 35

Decreased Na+ intake leads to what for oncotic pressure

Answer 35

Increased oncotic pressure, as you have a decreased volume, so pull more water and salt into the vasculature, increases Na reabsorption in the proximal tubule

Question 36

Regulation of salt and water reabsorption

Ang II pathway

Answer 36

Decreased ECV leads to increased RAAS, leads to increased ang II, leads to increased reabsorption of Na+, Cl-, and H2O in proximal tubule

Question 37

Regulation of salt and water reabsorption

Aldosterone pathway

Answer 37

Increased ang II or increased plasma K leads to increase in aldosterone, which leads to increase in reabsorption of Na and CL in the thick ascending limb of the loop of Henle, distal tubule, and collecting duct

Question 38

Regulation of salt and water reabsorption

ANP

Answer 38

Increased ECV or an increase in BP leads to atrial stretch, which leads to an increase in ANP, leading to an increase in natriuresis, leading to a decrease in total peripheral resistance, leading to a decrease in reabsorption of Na, Cl, and decrease ADH

Question 39

Regulation of salt and water reabsorption

Symp nerves

Answer 39

Decrease in ECV leads to increase in symp nerve activity, leading to increase in NE and E, leading to increase in reabsorption of Na and Cl in the proximal and distal nephron

Question 40

Regulation of salt and water reabsorption

Dopamine

Answer 40

Increase ECV leads to increase dopaminergic activity, leading to decreased reabsorption of Na and Cl in the proximal tubule

Question 41

Regulation of salt and water reabsorption

Antidiuretic hormone

Answer 41

Decrease ECV or increased plasma osmolality will leads to increased ADH, leading to increased reabsorption of H2O in collecting duct with little effect on Na and Cl excretion

Question 42

Causes of edema

Answer 42

Increase capillary hydrostatic pressure or decreased oncotic pressure