Unit 2, L17 Hormonal Regulation of Body Salts Flashcards
Why do your kidneys care about Na
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
Positive Na balance
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)
Negative Na balance
Na intake < Na excretion
Decreased ECF volume, leads to decreased blood volume, leads to decreased arterial pressure
ECV definition
Portion of ECF volume within the vascular system that is effectively perfusing the tissues
Relationship between ECV and AP and CO
Decreased ECF means decreased vascular volume, which means decreased AP, or decreased CO is sensed as decreased ECV
Vice versa for increased ECF
Low pressure senor for monitoring ECV
Increase stretch of cardiac atria, leads to increase in ANP, leads to increase Na excretion
High pressure sensors for monitoring ECV
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
Efferent responses to monitoring ECV
Neurohormonal: RAAS, SNS/catecholamines, ANP, BNP, and prostaglandins
Hemodynamic: GFR and peritubular forces
MD senses what?
Flow AND salt content in the lumen, gives TG feedback
If tubular flow and Na content is high, what will that cause
Contraction of afferent arterioles
Decreases GFR, maintains normal filtered load. Additionally, decreases renal secretion, allows for more Na excretion
If there is low flow and low salt, what will that produce
Prostaglanins and NO being released. This increases GFR to maintain normal filtered load, and increases renin secretion, conserves Na
Renin is produced by
JGA
High Na diet does what to renin
Suppresses secretion
Low Na diet does what to renin
Increases renin secretion
Renin is secreted by what
Granular JG cells on afferent arteriole just before the glomerulus
MD will control renin production how
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
Pressure of afferent arterioles will control renin production how
Intrarenal baroreceptors within the JG cells, they can sense a low pressure
How does symp nerve activity control renin production
Acts on JG cells via Beta 1 receptors on JG cells to produce renin
ANG II will promote the production of
ADH
Renin converts _____ to _____
Angiotensinogen to ANG I
ACE converts _____ to _____
ANG I to ANG II
ANG II stimulates _____ release from adrenal cortex
Aldosteronme
Function of adolsterone
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
ANG II function with arterioles
Constricts BOTH arterioles but has a greater effect on efferent, resulting in increase in GFR
ANP is synthesized and released from
Cardiac atria
Increase ANP leads to
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
Natriuretic peptides on the tubules
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
Increased Na+ intake leads to what for symp activity
Decreased symp activity, which increases GFR through dilation of afferent arterioles, decreases Na reabsorption in the proximal tubules, and increases overall Na excretion
Increased Na+ intake leads to what for ANP
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
Increased Na+ intake leads to what for RAAS
Decreases RAAS, so decreases Na reabsorption in the proximal tubule and collecting ducts, overall Na excretion increase
Increased Na+ intake leads to what for oncotic pressure
Decreases oncotic pressure, decreases Na reabsorption in the proximal tubule, and increases overall Na excretion
Decreased Na+ intake leads to what for symp activity
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
Decreased Na+ intake leads to what for ANP
Decreased ANP leads to dilation of efferent arterioles and decreased GFR, increasing Na reabsorption in the collecting ducts and decreasing overall Na excretion
Decreased Na+ intake leads to what for RAAS
Increased RAAS increases renin, through MD sensing it, to increase Na reabsorption in the proximal tubule and collecting ducts.
Decreased Na+ intake leads to what for oncotic pressure
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
Regulation of salt and water reabsorption
Ang II pathway
Decreased ECV leads to increased RAAS, leads to increased ang II, leads to increased reabsorption of Na+, Cl-, and H2O in proximal tubule
Regulation of salt and water reabsorption
Aldosterone pathway
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
Regulation of salt and water reabsorption
ANP
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
Regulation of salt and water reabsorption
Symp nerves
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
Regulation of salt and water reabsorption
Dopamine
Increase ECV leads to increase dopaminergic activity, leading to decreased reabsorption of Na and Cl in the proximal tubule
Regulation of salt and water reabsorption
Antidiuretic hormone
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
Causes of edema
Increase capillary hydrostatic pressure or decreased oncotic pressure
