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Salt & Water Balance

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Aldosterone, ADH, ANF
3 Hormones that control Salt and Water Balance.
Aldosterone
This hormone's main target is the kidney and it decreases Na+ excretion and causes water retention and increased blood pressure.
renin-angiotensin
Aldosterone is regulated by ___________ ___________ system involving kidney and liver.
Positively
Blood volume is ___________ correlated with blood pressure.
reabsorption
Blood volume is regulated by regulating sodium __________ in the kidney.
osmosis.
water follows Na+ by _____________
Blood volume
Increased Na+ = increased _______________
Glomerular Filtration
First step of urine formation is ___________ _____________.
Tubular reabsorption
Second step of urine formation is ______________ ________________.
tubular secretion
Third step of urine formation is ____________ ____________
excretion
Fourth step of urine formation is _________
Juxtaglomerular Apparatus
Main organ that regulates aldosterone. Part of the afferent arteriole wall.
Macula densa cells
These cells are part of the distal convoluted tubule wall and located next to juxtaglomerular cells
Juxtaglomerular apparatus
Juxtaglomerular cells and macula densa make up what?
chemical signals
Juxtaglomerular apparatus secrete ________ ________ that ultimately regulate aldosterone.
Sympathetic NS.
Juxtaglomerular apparatus gets activated when the _________ ________ is activated.
mean arterial pressure
A drop in this is sensed by baroreceptors and triggers a sympathetic response.
sympathetic nerves.
Juxtaglomerular cells richly innervated by ________ _________.
stretch receptors
Drop in Afferent Arteriole Blood Pressure is directly sensed by _________ __________ in juxtaglomerular cells.
Drop is Na+ reabsorpt
Glomerular Filtration Rate.
If there is less blood going to the kidney, less Na and water reabsorbed, this will lead to a drop in __________ __________ ________.
Macula densa cells
Drop is Na+ reabsorption in distal convoluted tubules is sensed by __________ __________ _____________.
Renin
When Juxtaglomerular apparatus is activated, __________ is secreted.
Angiotensinogen
Renin acts on __________ which is a large protein made by the liver and already circulating in high concentration in the blood.
Angiotensin I
Angiotensinogen is the substrate for renin and renin acts on it to produce _____________(.
Inactive
Angiotensinogen I is biologically ____________.
ACE
_____________ converts Angiotensinogen I to Angiotensinogen II (8AA).
Pulmonary circuit
Having Renin in the ________ _________, aids in the rapid conversion of Angiotensin I to Angiotensin II.
Glands, receptors.
Angiotensin II acts like a hormone, because it has __________ and ____________.
Blood Pressure
Angiotensin II increases __________ ___________. Thus a target of 40% of blood pressure medications.
Vasoconstriction
Angiotensin II directly causes widespread __________ of arterioles.
Cardiac
Angiotensin II directly causes increase ___________ excitability.
Peripheral resistance
Angiotensin II directly causes increased cardiac output + increased __________ ___________ = increased blood pressure
Aldosterone.
Angiotensin II indirectly acts on adrenal gland to stimulate secretion of ______________
Distal convoluted tubule.
Reabsorption of Na is in the ________ __________ ________
Na channels
Amount of _______ _________ present is limited by amount of Na available to Na+/K+ pump.
Renal outer medullary K
DCT have _________ channels on the lumen membrane.
K secretion
Renal outer medullary K account for _______ ________ into the cell.
SGK
____________ inactivates Nedd4-2.
Nedd4-2.
________ tags Na channels to be removed from the membrane.
Na
High levels of Aldosterone = higher concentration of ____________ channels in the membrane.
K
Aldosterone also promotes _____________ secretion.
Na, K.
Cant save ____ without losing _____.
Plasma osmolality.
Mechanism of maintaining BP has little effect on ________ __________ b/c Na and water are moved along together.
AVP
Hormone the helps in regulating plasma osmolality and regulates urine output.
Hypothalamus,
AVP is synthesized in the ___________.
secretory granules
Once synthesized, AVP is packaged into ___________ _________ and transported down axons to posterior pituitary.
Magnocellular, Parvocellular
AVP is synthesized in two populations of cells, ___________ and ____________ neurons.
Posterior pituitary
Magnocellular projects to ____________ ____________
median emminence
Parvocellular projects to _____________ ___________
Dehydration
AVP Stimuli for Secretion. Blood plasma becomes more concentrated.
increase
AVP Stimuli for Secretion is expressed by __________ in plasma osmolality.
decrease
AVP will cause a dramatic _________ in blood volume (in emergency situation).
Antidiuresis, Vasoconstriction.
Effects of Vasopressin are ___________ and ____________
ADH
___________ concentrates urine to retain water in body and decrease osmolality of the blood.
V2, moderate
Antidiuresis is mediated through high affinity _______ receptors in the kidney at _______ levels of ADH. (day to day regulation).
Vasoconstriction
_____________ helps maintain blood pressure when blood volume drops. (Hemorrhage)
V1, high
Vasoconstriction is mediated by lower affinity ___ receptors that require _________ levels of ADH to be activated.
IP3, Ca
V1 _____ signaling pathway increases ______ which constricts muscle.
a1 adrenergic
V1 has same mechanism as ______ __________ receptors
V2
_____ pathway uses classic cAMP pathway to increase water reabsorption.
Loop of Henle
__________ create high solute concentrations.
High osmotic gradient
_________ _______ _________ allow water to leave.
AVP.
Permeability of collecting ducts to H2O regulated by _______
Dilute
If collecting duct is impermeable to water, you get ____________ urine. (When you are hydrated)
ADH
________ produced during dehydration.
Increases, concentrated.
ADH _________ permeability of collecting ducts to water. Resulting in _________ urine.
Osmosis.
In the collecting ducts, water reabsorbed from filtrate by __________, is leaving concentrated urine
aquaporins
Collecting duct epithelial cells contain vesicles with HIGH concentration of _______ (water channels)
exocytosis
Secretion of ADH causes __________ of vesicles with aquaporins. (Their contents get dumped out of the cell)
Outer
In the process of exocytosis, aquaporin membranes fuse with ______ cell membrane.
Increases permeability
After exocytosis, aquaporin loaded membranes are incorporated into the cell membrane. This greatly _________ ___________ to H2O.
ANF
__________ is secreted by cells in the atrium of the heart and opposes the actions of aldosterone.
BP, increases, Na.
ANF lowers _________,
___________ blood volume,
Increases _____ excretion.
hypervolemia
Activation of stretch receptors in atrium indicates ___________ (too much blood volume)
G-protein coupled, cGMP
AVP uses ____________ receptors that use ___________ as a second messenger.
cGMP
AVP receptors activate ________ dependent kinases.
arterioles, heart,
ANF vasodilates __________
Reduces sympathetic stimulation of __________________. (calms it down)
juxtaglomerular apparatus
Reduces sympathetic stimulation of _________ ____________ so it does not activate to oppose its actions.
glomerular filtration rate, aldosterone, AVP
ANF Increases ______________ ________________ _______________ by relaxing the afferent arterioles - more Na+ and water removed & it directly inhibits ____________secretion by the adrenal gland
Inhibits ____________ secretion by the posterior pituitary.