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APK2105C CH 19
N/A
67
Physiology
Undergraduate 2
12/12/2012

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Term
Body (mostly the kidneys) can change how much they reabsorb water and Na+ but do NOT _________
Definition
Secrete it
Term
Nearly all the water enters the body through the ________
Definition
Digestive Tract
Term
Water leaves the body through
Definition
-Insensible loss from skin and respiration
-Sweat
-Digestive Waste
-Urine Excretion **
Term
Plasma volume impacts _____ and _______
Definition
MAP and Osmolarity
Term
Hypervolemia
Definition
Increased plasma volume
Term
Hypovolemia
Definition
Decrease plasma volume
Term
Increased water, but not increased solute =
Definition
decreased osmolarity
Term
Decreased water, but not increased solute =
Definition
increase osmolarity
Term
In renal tubules, water reabsorption
Definition
is passive and is coupled to the active reabsorption of solutes
Term
In proximal and distal tubules, reabsorption of solute (increase/decreases) the osmolarity of the peritubular fluid, which drives _________
Definition
increases
drives reabsorpotion of water by osmosis
Term
In the collecting duct, ___________ drives reabsorption of water
Definition
medullary osmotic gradient
Term
An __________ always drives water reabsorption (Filtration)
Definition
Osmotic gradient
Term
What is the primary solute in ECF?
Definition
Na+, therefore it is responsible for water reabsorption
Term
70% of all Na+ is reabsorped in the __________
Definition
Proximal convoluted tubule (Water follows)
Term
What are the steps for Water and Urea reabsorption?
Definition
1) Solutes (Na+, X, Y) are actively reabsorbed, increasing the osmolarity of peritubular fluid and plasma
2) Water is reabsorbed by osmosis
3) Urea (permeating solute) is reabsorbed passively
Term
Fluid in the proximal tubule is _________ with interstitial fluid of the renal cortex
Definition
iso-osmotic (300 mOsm)
Term
Medullary Osmotic Gradient
Definition
established by the loop of Henle in juxtamedullary nephrons
-outer region: 300 mOsm (iso-osmotic)
-Inner region: 1200-1400 mOsm (highly concentrated with solutes)
Term
Countercurrent Multiplier ______ the gradient
Definition
established
Term
Transport of urea out of the collecting duct _______ the gradient
Definition
maintains
Term
Countercurrent multiplier refers to the
Definition
the two limbs of the Loop of Henle are moving in opposite directions
Term
The _____________ is permeable to water, therefore there is _____ Na+, K+, Cl- transport
Definition
Descending Limb
NO
Term
The __________ is impermeable to water, and (is/isn't) a cotransporter of Na+, K+, Cl-
Definition
Thick ascending limb
Is
Term
In the countercurrent multiplier, initially all fluids are iso-osmotic, but what action increases the osmolarity of the interstitial fluid and decreases the osmolarity of the tubular fluid?
Definition
Active transport of solutes (Na+, Cl-, K+) from the ascending limb of the loop of Henle into the medullary interstitial fluid
Term
In the countercurrent multiplier, the increased osmolarity of the medullary interstitial fluid causes what?
Definition
Water to be drawn from the lumen of the descending limb of the loop of Henle into the interstitial fluid
Term
(countercurrent multiplier) After water moves out of the descending limb by osmosis, there is an ________ state in the descending limb, but an osmotic difference in the _________ and _______ limbs
Definition
iso-osmotic
descending and ascending limbs
Term
(countercurrent multiplier) At steady state...
Definition
the fluid entering the loop of Henle from the proximal tubule is iso-osmotic to extracellular fluid
Term
Main steps to countercurrent multiplier to reach medullary osmotic gradient
Definition
1) Fluid enters tubule
2) Active transport of ions into medullary interstitial fluid (increases osmolarity)
3) Water moves out of descending limb by osmosis
4) Iso-osmotic state in descending limb; Osmotic difference between descending and ascending limbs
Term
Urea
Definition
waste product generated during protein catabolsim
Term
Urea is ______ transported out of the _________ to (increase/decrease) osmolarity in interstitial fluid
Definition
actively
collecting duct
increase
Term
The fluid in the distal tubule and collecting duct is hypo-osmotic to the ____________, which creates _____________
Definition
medullary interstitial fluid
an osmotic force for water to leave the tubules
Term
When the membrane of the late distal tubule and collecting duct is IMPERMEABLE to water, water
Definition
cannot leave the the tubule and is excreted in the urine, producing a large volume of urine with low osmolarity
Term
When the membrane is highly permeable to water, the final urine
Definition
is iso-osmotic with the deepest layers of the renal medullar, producing a small volume of urine with high osmolarity
Term
Urine will ______ be more concentrated than the concentrated medulla
Definition
NEVER
Term
The epithelial walls of the late DCT and CD are
Definition
NOT permeable to water
Term
Aquaporins are necessary to
Definition
make epithelial walls permeable to water
Term
Aquaporin-3 is
Definition
ALWAYS present in the basolateral membrane
Term
Aquaporin-2 is
Definition
present in the apical membrane and ONLY in the presence of the hormone ADH
Term
Obligatory Water loss
Definition
440 mL of water per day that must be excreted to eliminate substances
Term
Longer loops of Henle can
Definition
form a larger medullary osmotic gradient by the countercurrent multiplier, therefore allowing greater water reabsorption (smaller obligatory water loss and stronger ability to conserve water)
EX: Camels and Australian hopping mice (longest loops of Henle)
Term
Antidiuretic Hormone (ADH)
Definition
(Vasopressin) regulates the permeability of the late distal tubules and collecting ducts to water
Term
At high concentrations of ADH, water reabsorption is ______ and urine output is _____
Definition
Water reabsorption is high
Urine output is low
Term
ADH is secreted from the __________ by _________ cells that originate in the _________
Definition
posterior pituitary gland
Neurosecretory cells
Hypothalamus
Term
Osmoreceptors in the hypothalamus....
Definition
monitor the osmolarity of extracellular fluid
Term
If osmolarity increases, ADH secretion is (stimulated/inhibited) which (increases/decreases) water reabsorption
Definition
Secretion is stimulated
Increased Water Reabsorption
Term
Increased Osmolarity of extracellular fluid = (Hypothalamus) Osmoreceptors detect and respond = (Increase/Decrease) Activity of neurosecretory cells in hypothalamus= (Increase/Decrease) ADH secretion in Posterior Pituitary = (increase/decrease) water reabsorpotion in the kidneys = (increase/decrease) Water excretion = Conservation of Body Water (negative feedback)
Definition
Increase activity of neurosecretory cells
Increase ADH secretion
Increase Water reabsorption
Decreases Water Excretion
Term
Decreased MAP or Decreased Blood Volume = Baroreceptors detect and respond = (Increase/decrease) activity of neurosecretory cells in hypothalamus = (increase/decrease) ADH secretion in Posterior Pituitary = (increase/decrease) Water reabsorption in the kidneys = (increase/decrease) Water excretion = Conservation of blood volume (negative feedback)
Definition
Increase in activity of neurosecretory cells
Increase in ADH secretion
Increase in Water Reabsorption
Decrease in Water Excretion
Term
If osmolarity decreases, then ADH secretion is (inhibited/secreted), which (increases/decreases) water reabsorption and (increases/decreases) water excretion
Definition
ADH inhibited
Decreases Water reabsorption
Increases Water Excretion
Term
If blood volume or blood pressure increases, ADH secretion is (increased/decreased), resulting in (increases/decreased) water excretion, which decreases blood volume and blood pressure
Definition
ADH secretion is decreases
Increased Water excretion
Term
If blood pressure drops below 80 mmHG, then the GFR
Definition
decreases
Term
Na+ is freely filtered at the glomerulues and undergoes tubular reabsorption but it is not
Definition
secreted
Term
Na+ is filtered at the
Definition
glomerulus
Term
Regulation of plasma Na+ occurs only at the level of
Definition
reabsorption
Term
Aldosterone is
Definition
a steroid hormone that is released from the adrenal cortex in response to Angiotension II and secretion of potassium
Term
Aldosterone increases Na+ reabsorption by
Definition
1) opening Na+ and K+ channels on apical membrane
2) Increases number of Na+/K+ pumps on the basolateral membrane
Term
Renin
Definition
Like a hormone, but really a proteolytic enzyme
Term
When sodium concentration in the tubular fluid decreases, renin secretion
Definition
Increases
Term
Renin acts on a protein that is always present in the plasma, ________
Definition
Angiotensinogen (secreted by the liver)
Term
Renin is found
Definition
in the granular cells within the walls of the afferent arteriole, that in formed from the juxtamedullary apparatus
Term
Four ways in which Angiotensin II increases MAP
Definition
1) Stimulates Vasocontriction of systemic arterioles (Increases TPR = Increased MAP)
2) Stimules Adrenal cortex to secrete aldosterone (increases sodium reabsorption = water reabsorption to increase)
3) Stimulates posterior pituitary to secrete ADH, which increases water reabsorption (maintaining fluid loss and plasma volume)
4) Activates hypothalmic neurons to stimulate thirst and fluid intake, which increases plasma volume (increasing MAP)
Term
A Decrease in MAP =
(increase/decrease) Afferent Arteriole Pressure
(Increase/decrease) Sympathetic activity
(increase/decrease) GFR
(Increase/decrease) Na+ and Cl-
(increase/decrease) Paracrine Secretion
===== (increase/decrease) renin release
Definition
decrease Afferent Arteriole Pressure
Increase Sympathetic activity
decrease GFR
decrease Na+ and Cl-
increase Paracrine Secretion
===== increase renin release
Term
Renin-Angiotensin-Aldosterone System
Definition
(Liver)--> Angiotensinogen --> (juxtaglomerular cells in kidney) --> Renin --> Angiotensin I --> (Capillary endothelial cells) --> Angiotensin II --> Adrenal Cortex --> Aldosterone
Term
Plasma solute concentration directly or indirectly affects __________
Definition
-mean arterial pressure
-plasma volume
-the amount of water in the various body fluid compartments
Term
If blood pH increases,
Definition
An increase in blood alkalinity would trigger an increase in H+ ion reabsorption from the kidney tubule.
Term
An osmotic gradient develops in the renal medulla because various parts of the loop of Henle differ from each other by
Definition
-active transport of solutes
-permeability to water
-direction of fluid movement
Term
Depending on the location in the kidney tubule, sodium ion reabsorption may be directly or indirectly linked to _______ transport.
Definition
Glucose, Chloride and Potassium
Term
Fluid leaving the loop of Henle is _______ in volume and ________ to the fluid entering the loop.
Definition
lower; hypo-osmotic
Term
Angiotension II stimulates
Definition
Release of ADH and Aldosterone
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