Renal Flashcards
What is the pathway of blood supply to the kidleys?
Renal Artery, Afferent Arterioles, Glomerular Capillaries, Efferent Arterioles, Peritubular Capillaries, Renal vein
What is the function of the Glomerulus?
Filtration membrane across capillaries: provides filtration of blood cells and most proteins
What are fenestrations?
large pores in endothelial cells
What are Mesangial cells?
Contractile cells located around glomerulus that help regulate how much surface area is available for glomerular filtration-when contracting the surface area for filtration decreases
What is the function of Juxtaglomerular apparatus?
helps regulate blood pressure
What are the functions of the kidney and urinary system?
excretion of metabolic waste products and foreign chemicals, regulate plasma volume, and blood pressure, regulate osmolarity and electrolytes, Vit. D synthesis, Erythropoietin synthesis, acid base balance, and gluconeogenesis
The efferent arteriole is ____ in diameter than the afferent arteriole in the kidney?
smaller
Resistance to blood outflow is high which _____ blood pressure within glomerulus?
increases
Capsular oncotic pressure is typically what?
zero, unless there is a pathological condition present
GFR=
Kf * net filtration pressure
what does Kf equal?
12.5
Constriction of afferent arteriole ____ blood flow into glomerulus
decreases
Constriction of afferent arteriole _____ blood hydrostatic pressure
decreases
Constriction of afferent arteriole ___ GFR
decreases
Constriction of efferent arteriole ___
outflow of blood from glomerulus
Constriction of efferent arteriole ___ blood hydrostatic pressure in glomerulus
increases
Constriction of efferent arteriole ____ GFR
increases
SNS causes ____ of afferent and efferent arterioles
vasoconstriction
What effect does ANGII have on the glomerulus?
vasoconstricts efferent arteriole
What effect does ANP have on the glomerulus?
dilates afferent arterioles
what effect does Norepi and Epi have on the glomerulus?
vasoconstricts afferent and efferent arterioles
what effect does Nitric oxide have on the glomerulus?
causes vasodilation of afferent arteriole
what effect do prostaglandins have on the glomerulus?
vasodilates afferent arteriole
what effect does endothelin have on the glomerulus?
vasoconstricts afferent arteriole
How would arteriosclerosis in the afferent arteriole decrease GFR?
decrease glomerular hydrostatic pressure
How would a kidney stone in a ureter decrease GFR?
increase capsular hydrostatic pressure
What effect does ANGII have on GFR?
Increase
What effect does ANP have on GFR?
Increase
What effect do prostaglandins have on GFR?
increase
what effect does strong SNS stimulation have on GFR?
Decrease
Secretion of H+ ions is essential for reabsorption of what?
HCO3-
What catalyzes H2CO3- into water and CO2?
carbonic anhydrase
What would happen to the HCO3- reabsorption in the PCT if the sodium/potassium ATPase in those cells was inhibited?
It would decrease because there will be a loss of the ion gradient to keep the H+ ions flowing with the sodium Hydrogen anti-porter
Where in the kidney pathway does urine become hypotonic?
ascending LOH and early DCT
How can inhibition of the Na/Cl/K symporter lead to hypomagnesemia?
This will block the K gradient building in the lumen which will lead to less positive pressure there to drive the Mg back into the blood.
If you increase sodium delivery you will increase potassium ____
secretion
A carbonic anhydrase inhibitor acting in the CD will cause alkalosis or acidosis?
Acidosis
Furosemide will have what effect on K+ secretion in the CD?
Increase; sodium reabsorption is inhibited in the LOH so there is more sodium in the filtrate and when it reaches the CD at that concentration a lot more sodium reabsorption occurs
Hyperaldosteronism can cause (hyper or hypokalemia) and (acidosis or alkalosis)
Hypokalemia and alkalosis
SNS stimulation and a drop in renal perfusion will ____ stimulation of renin
increase
Hyperkalemia can also _____ the aldosterone secretion
stimulate
What does ADH do to reabsorption?
increase reabsorption of water
What does ANGII do to reabsorption?
Increases Na and water reabsorption and secretion of H in PCT by stimulating Na/H anti-porters
What does Aldosterone do to reabsorption?
stimulates release of aldosterone form adrenal gland. Increases Na reabsorption and secretion of K in principle cells. Stimulates H from intercalated cells.
What does ANP do to reabsorption?
Released from atrial cells in response to stretching…directly inhibits Na reabsorption in the CD and suppresses secretion of renin
what is the effect of PTH on reabsorption?
Released in response to hypocalcemia and increase Ca reabsorption in thick ascending LoH and early DCT…decreases HPO4 reabsorption in PCT
In the PCT, the osmolarity of the filtrate (does/does not) change
does not; due to both water and solutes being reabsorbed
In the descending LOH, filtrate becomes (more/less/same) concentration because…
more because only water is reabsorbed
In the ascending LOH/early DCT, filtrate becomes (concentrated/dilute/remains neutral) since…
dilute since solutes are reabsorbed, but not water
In the late DCT and CD, filtrate becomes (more/less) diluted because… (trick question…but why?)
more diluted in the absence of ADH…less with ADH
What are the requirements for excreting concentrated urine?
ADH and hyperosmotic medullary interstitium
Substances that slow renal reabsorption of water cause what?
cause diuresis and therefore decreases blood volume
Caffeine does what to the kidneys?
inhibits Na reabsorption
Alcohol does what to the kidneys?
inhibits ADH secretion
pH= (classical formulation)
-log[H+]
pH= (Henderson-Hasselbalch Equation)
6.1 + log (HCO3-/.03 * PCO2)
Only multiply by .03 in the Henderson-Hasselbalch Equation if you (Did/Did Not) get the concentration of CO2?
Did Not
H+ secreted by PCT is essential to reabsorb what?
HCO3-
H+ secretion is driven by what?
Na reabsorption
As PCO2 levels rise in the blood and filtrate, there will be (less/more) H+ secretion leading to (more/less) HCO3- reabsorption?
more, more
What is the initial problem in Respiratory acidosis?
Increased PCO2 due to hypoventilation causes decreased pH
What compensation occurs during Respiratory acidosis?
Increased renal secretion of H+ and reabsorption of HCO3-…pH still slightly low even with compensation
what is the initial problem with Respiratory alkalosis?
Decreased PCO2 due to hyperventilation…increased pH
What is the compensation that occurs during respiratory alkalosis?
Decreased reabsorption of HCO3- and secretion of H+… pH will be slightly over 7.4
What is the initial problem during Metabolic alkalosis?
Increased free HCO3- (due to loss of acids or gain of HCO3-…increased pH
What is the compensation that occurs with Metabolic alkalosis
Hypoventilation causes increase PCO2 and pH will be slightly high
what is the initial problem with Metabolic acidosis?
Decreased pH, accompanied by decreased free HCO3- (due to gain of acids or loss of HCO3-
what is the compensation that occurs with Metabolic acidosis?
Hyperventilation which decreases PCO2 and the pH will be slightly low
What can the Anion gap tell you?
if metabolic acidosis is due to loss of HCO3- from the body or an accumulation of acids
Anion Gap=
Na- (Cl + HCO3-)
Normal Anion Gap values range from
8-16 mEq/L
If anion gap is normal, metabolic acidosis is due to what?
loss of HCO3- from the body
What can happen with an accumulation of H+ released from acids in metabolic acidosis due to accumulation of acids?
binds to HCO3- which decreases free HCO3- which decreases and the anion gap increases
Acidosis causes exchange of extracellular ___ for intracellular ____
H+ for K+
Alkalosis causes exchange of intracellular ___ for extracellular ____
H+ for K+
What is renal clearance?
volume of plasma from which a particular substance is completely removed per unit time (ml/min)
A substance can be cleared from the blood by the kidneys via what?
filtration and/or secretion (not reabsorbance)
To see if a substance has net reabsorption or secretion then compare it to what?
GFR of inulin/SCR and if it is higher then it is secreted
what is the formula for GFR?
(Uinulin*V)/Pinulin
What is the normal value of GFR?
125ml/min
what is the normal range of CrCL?
90-140 ml/min
which is more accurate and why (inulin vs. CrCl)
inulin…it is completely secreted from the body as the body has no physiologic need for/from it.
What is the formula for reabsorption?
filtered load - excretion rate
what is the formula for filtered load?
GFR*Ps
What is the formula for excretion rate?
Us * V
If a substance is bound to a protein such as albumin how will this affect its filtration?
decrease
What is the formula for secretion rate?
excretion rate - filtered load
What characterizes Acute renal failure?
A decrease in glomerular filtration rate
What is oliguria?
diminished urine output
What is anuria?
total cessation of urine output
What are pre-renal causes of acute renal failure?
result in decreased glomerular hydrostatic pressure and therefore decreased GFR. Comes from a decrease in intravascular volume or loss of effective blood volume
Renal failure due to kidney stones would be characterized as what?
Post-renal cause
Post-renal causes of renal failure decrease GFR by what mechanism?
increasing capsular hydrostatic pressure
Renal failure due to an ACE inhibitor would be characterized as what?
A pre-renal cause
Pre-renal causes of renal failure decrease GFR by what mechanism?
Decreasing glomerular hydrostatic pressure
What is the mechanism of an ACE inhibitor?
blocks vasoconstriction of efferent arteriole by ANGII which can lead to vasodilation and decreased GFR
What is the mechanism of an NSAID upon the kidleys?
block synthesis of prostaglandins and interfere with afferent arteriolar vasodilation causing a decrease in GFR
What is an Intrarenal cause of renal failure?
when direct damage occurs to the kidney rather than an obstruction or perfusion issue
What is a post-renal cause to renal failure?
obstruction of urine flow
Chronic renal failure will cause a ____ number of functioning nephrons and therefore a ____ GFR?
decreased, decreased
What can cause proteinuria?
damage to the glomerulus
What will prostaglandins do to the renal system?
mediated afferent arteriolar vasodilation in nephrons
what will ANG II do to the kidneys?
mediated efferent arteriolar vasoconstriction in nephrons
How can an ACE inhibitor delay the progression of chronic kidney failure?
by blocking ANGII which will cause vasodilation in efferent arterioles thus decrease glomerular hydrostatic pressure and preserves nephrons thru this mechanism.
Can chronic kidney disease be present with a normal or near normal GFR?
yes, if other markers are present
Serious symptoms usually do not occur in chronic renal failure until what?
loss of 70-75% of nephrons
what is the most common cause of death from renal failure?
cardiac dysfunction
