Questions derived From bRS Phys Flashcards
At steady state, ECF and ICF osmolarity are?
The same
What happens in the infusion of Isotonic NaCl?
ECF volume increases (no change occurs in osmolarity and therefor no shift of water to ICF)
Plasma [protein and hematocrit] decreases
Arterial blood pressure increases
What changes occurs in diarrhea (loss of isotonic fluid)
ECF volume decreases (but no change occurs in the osmolarity, so water does not shift from ICF)
Plasma [protein and. Hematocrit] increase
Arterial blood pressure decreases
What occurs in excessive NaCl intake?
Osmolarity of ECF increases
Water shifts from ICF to ECF (causing ICF osmolarity to increase)
ECF volume increases and ICF volume decreases
Plasma [protein and hematocrit] decrease bc of the increase in ECF volume
What happens in sweating in a desert? (Hyperosmotic volume contraction)
ECF osmolarity increases (more water than salt lost in sweat)
ECF Volume decreases -> water shifts from ICF to ECF -> ICF osmolarity increases to equal ECF
ICF volume decreases
Plasma [protein] decreases (hematocrit concentration stays the same due to the loss of fluid from RBC’s)
What happens in Syndrome of inappropriate antidiuretic hormone? (Gain of water)
Osmolarity of ECF decreases
ECF volume increases, water shifts to cells, ICF osmolarity decreases, ICF volume increases
Plasma protein concentration decreases
(Hematocrit remains same bc water shifts into RBC’s)
What happens in adrenocortical insufficiency (loss of NaCL)
Aka hyposomotic volume contraction
Osmolarity of ECF decreases
Water shifts into cells, ecf volume dcreases, ICF osmolarity decreases, ICF volume increases
Plasma [protein] increaases
Hematocrit concentration increases
Arterial blood pressure decreases
Vasoconstriction of renal arterioles occurs due to ?
Activation of sympathetic nervous system
Angiotensin II
What causes vasodilation of renal arteries ?
Prostaglandins E2 and I2, bradykinin
Nitric Oxide
Dopamine
Autoregulation of renal blood flow is accomplished by ?
Changing renal vascular resistance
(Myogenic mechanism - stretch reflex)
(Tubuloglomerular feedback - macula densa senses increased load and causes constriction in nearby afferent arteriole)
RBF is constant over a blood pressure range of ?
80-200mmHg
What happens to BUN and creatinine when GFR decreases?
They both increases
In prerenal azotemia (hypovolemia) BUN increases ____ than serum creatinine and there is a _______ BUN/creatinine ratio
More
Increased
Normal filtration fraction ?
0.20
FF = GFR/RPF
Increases in filtration fraction leads to ?
Increased protein concentration of peritubular capillaries and increased reabsorption in the proximal tubule
Decrease in filtration fraction leads to ?
Decreases in concentration of protein in the peritubluar capillaries and a decrease in reabsorption in the proximal tubule
The glomerular barrier consists of ?
The cappillary endothelium
Basement membrane
Filtration slits of the podocytes
What causes increases in Bowmans space hydrostatic pressure?
Constriction of the ureters
Increases in glomerular capillary protein concentration cause ______ in net ultrafiltration pressure and GFR
Decreases
______ in the proximal tubule reabsorbs glucose from tubular fluid into the blood
Na-Glucose cotransport
RPF is measured by the clearance of PAAH at plasma concentrations of PAH that are ______ than at Tm
Lower
Parathyroid hormone causes ______ and increased urinary ______
Phosphaturia
.cAMP
The ______ and _____ reabsorb more than 90% of the filtered calcium by passive processes that are coupled to Na reabsorption
Proximal tubule and thick ascending limb
_____ % of plasma calcium is filtered
60
Loop diuretics (Furosemide) cause ____ urinary calcium excretion
Increased
[urinary calcium is linked to Na reabsorption in the loop of henle. Inhibiting Na reabsorption therefore also inhibits Ca reabsorption]
The _________ and _________ reabsorb 8% of the filtered calcium by an active process
Distal tubule and collecting duct
How does PTH increase calcium reabsorption in the kidney?
By activating adenylate cyclase in the distal tubule.
Thiazide diuretics _____ calcium reabsorption in the early distal tubule
Increase
In the thick ascending limb, Mg and Ca ______ for reabsorption, therefore, hypercalcemia causes an increase in Mg Excretion and vice versa
Compete
Hyperosmotic urine is produced when circulating _____ levels are high
ADH
Gradient of osmolarity from the cortex to the papilla. Composed primarily of NaCl and urea. Established by countercurrent multiplication and urea recycling. Maintained by countercurrent exchange in the vasa recta
Corticopapillary osmotic gradient
Gradient of osmolarity from the cortex to the papilla. Composed primarily of NaCl and urea. Established by countercurrent multiplication and urea recycling. Maintained by countercurrent exchange in the vasa recta
Corticopapillary osmotic gradient
Countercurrent multiplication in the loop of henle is dependent on?
NaCl reabsorption in the thick ascending limb and countercurrent flow in the descending and ascending limbs of the loop of Henle
(It is augmented by ADH which stimulates NaCl reabsorption in the thick ascending limb)
The presence of ADH ______ the size of the corticopapillary osmotic gradient
Increases
The capillaries that supply the loop of henle
Vasa recta
Maintain corticopapillary gradient by serving as osmotic exchangers.
Blood from this equilibriates osmotically w/ the interstitial fluid of the medulla and papilla
Vasa recta
When producing concentrated urine, _____ of the filtered H2O is reabsorbed isosmotically (with Na, Cl, Bicarb, gluc) in the proximal tubule
2/3
The thick ascending limb of the loop of henle, with high ADH (making hyperosmotic urine) is called the ______
Diluting segment
In High ADH (hyperosmotic urine) the thick ascending limb of the loop of henle reabsorbs ______ by _______, and is impermeable to _______
NaCl
Na-K-2Cl cotransporter
H2O
The TF/Posm after the thick ascending limb in high ADH (hyperconcentration of urine) has a TF/Posm that is ___ 1.0
TF/Posm < 1.O
The early distal tubule in situations of high ADH is ______ to water
Impermeable
ADH ______ the H2O permeability of the principal cells in the late distal tublule
Increases
ADH ______ the H2O permeability of the principal cells of the collecting ducts in high ADH scenarios
Increases
Hyposmotic urine is produced when ?
Circulating ADH levels are low or ADH is ineffective
______ stimulates both countercurrent multiplication and urea recycling
ADH
In the absence of ADH what happens to water in the proximal tubule /?
The same as in situations of high ADH
About 2/3 of the filtered water is absorbed isosmotically in the proximal tubule
In no ADH, what happens in the thick ascending limb of the loop of henle ?
Same as w/ in Presence of ADH (but not as much as in it )
NaCl reabsorbed w/o water and the tubular fluid becomes dilute
What happens in the early distal tubule in no ADH
Same as w/ presence of ADH
NaCl is reabsorbed w/o H2O and tubular fluid is further diluted
What happens in the late distal tubule and collecting ducts in the absence of ADH ?
The cells here are impermeable to water in the absence of ADH
Even though fluid flows thru the corticopapillary osmotic gradient, the osmotic equilibration does not occur
Osmolarity of final urine dilut
What part of the nephron is free water produced in ?
The diluting segments
The thick ascending limb and the early distal tubule
In the absence of ADH, Ch2o is _____-
Positive
In the presence of ADH, Ch2o is
Negative
Ch2o =
V - Cosm
Urine that is isosmotic to plasma (Ch2o = 0) is produced when treatment with ?
Loop diuretics
Because these will inhibit NaCl reabsorption in the thick ascending limb. Inhibiting both dilution in the thick ascending limb and production of the corticopapillary osmotic gradient, therefore, the urine cannot be diluted during high water intake or concentrated during water deprivation
What can lead to the production of urine that is hyposmotic to plasma ?
High water intake
Central diabetes insipidus
Nephrogenic diabetes insipidus
(These all lead to low or innefective ADH )
What can cause urine that is hyperosmotic to plasma ?
(High ADH)
Water deprivation
SIADH
An acid produced from carbon dioxide
Can be excreted by the body by ventilation
Volatile acid
An acid such as lactic acid or sulfuric acid that accumulates in the body as a result of digestion, dz, or metabolism. Must be excreted from the body by organs other than the lungs (urine)
Nonvolatile acids
Reabsorption of filtered HCO3- occurs primarily in the _____-__
Proximal tubule
Increases in Pco2 result in ______ rates of HCO3- reabsorption
Increased
ECF volume expansion results in________ HCO3- reabsorption
Decreased
ECF volume contraction results in _______ HCO3- absorption
Increased
Angiotensin II ______ Na-H exchange and thus _______ HCO3- reabsorption
Stimulates
Increases
Fixed H produced from the catabolism of protein and phospholipid is excreted by which two mechanism?
Titratable acid and NH4
H-ATPase is _____ by aldosterone
Increased
NH3 is produced in renal cells from ______
Glutamine
Hyperkalemia ______ NH3 synthesis
Inhibitis
