Unit 1 Renal Flashcards
How does high salt intake contribute to greater excretion calcium in the kidneys
Since Ca2+ is coupled to Na+ reabsorption in the PCT, when there’s an increase in salt intake theres a decrease in salt reabsorption theres also a decreased Ca2+ reabsorption (inc. excretion).
What percent of Calcium is reabsorbed in the PCT?
65%
What is the MOA of calcium reabsorption in the PCT
Electrochemically- paracellularly
As the lumen have a net positive potential, calcium moves passively (REGULATED by Na+ reabsorption)
What is the MOA of calcium reabsorption in the TAL
Electrochemically- paracellularly
As the lumen develops a net positive potential due to the NKCC co transporter, calcium is reabsorbed paracellularly
What parts of the nephron reabsorbs calcium
PCT, TAL, DCT
What is the MOA of calcium reabsorption in the DCT
Actively-transcellular
PTH regulated process
What percent of calcium is reabsorbed in the TAL?
20%
What percent of calcium is reabsorbed in the DCT
7-10%
What can alkalemia do to calcium?
It can cause hypocalcemia. this is because theres less protons binding to proteins, which leads free calcium to bind to proteins. this causes less active calcium, thus hypocalcemia.
What is low when someone has diarrhea?
Bicarb—-> metabolic acidosis
What is low when someone is throwing up excessively?
HCl—-> metabolic alkalosis and hypochloremia
What kidney arterioles does angiotensin II affect?
Both afferent and efferent, BUT efferent more
Causes vasoconstriction
How does angiotensin II affect the filtration fraction?
A2 causes decreased RFF due to constriction of both renal arterioles.
GFR decreases overall as well but not as much as RPF due to increased constriction of efferent arteriole, which slightly increases GFR
Therefore, FF is increased
How does an increased FF change peritubular capillary oncotic pressure
Since more plasma is filtered into the glomerulus, this leaves more a higher protein concentration leaving the efferent arteriole, thus the oncotic pressure of the peritubular capillaries is higher.
What does the JGA regulate?
BP, GFR, renin secretion
Where is the JGA located?
Between the afferent arteriole and DCT
What components make up the JGA?
Mucula Densa
Juxtaglomerular cells
Mesangial cells
Function/location of macula densa
Regulate NaCl concentration
-if NaCl is high in DCT–> inhibits renin release (from JG cells)–> dec. aldosterone–> inc. Na excretion
-if NaCl is low in DCT–> stimulates renin release (from JG cells)–> inc. aldosterone–> inc. Na reabsorption
Located in the DCT where it meets afferent arterioles
Function/location of JG cells
Location: in the afferent arterioles near the macula densa
Regulates BP by secretion/inhibition of renin
Function/location of mesangial cells
between JG cells and macula densa
function = unknown
what can cause post-renal damage
Kidney stones, they can block ureters, cause back flow which can lead to AKI
Roadmap of how decreased renal artery resistance and lead to increased oxygen consumption.
Dec. resistance—> inc. flow–? increases hydrostaic pressure of arteriole–> Inc GFR –> Inc. sodium (normal) in tubule —> more transporters needed for reabsorption —> more Na-K ATPase —> increased O2 consumption
Calculate new plasma osmolarity of 80kg man who drank 2L of water
288 mOsm/L
What transporter is messed up in type 1 RTA
All in DCT and CD
-H+ ATPase –> decreased H+ secretion –> metabolic acidosis
What transporter is messed up in type 2 RTA
In PCT
-Na/H+ exchanger —> Decreased reabsorption of Bicarb–> Metabolic acidosis
-Na/Bicarb cotransporter –> decreased reabsorption of bicarb—> metabolic acidosis
What transporter is messed up in type 4 RTA
in DCT and CD
-Na transporters insensitive to aldosterone—> ENaC isnt working–> decreased Na+ reabsorption–> dec. proton pump activity–> dec. proton excretion–> metabolic acidosis
which RTA’s have hyperkalemia?
type 4 because aldosterone transporters arent working—> decreased K+ exchange—> dec. K+ excretion —> hyperkalemia
Which RTA’s have hypokalemia?
Type 1 and 2
this is due to decreased sodium reabsorption in proximal and distal convoluted tubules which leads to increased sodium reabsorption in the collecting duct, which leads to increased potassium excretion –> hypokalemia
Which RTA has kidney stones
RTA type 1, due to very alkaline urine.
What is the free water clearance equation?
V - Cosm
= V - (Uosm x V)/ Posm
answer can be negative
What does a negative Ch2o mean?
Body is conserving water
What does a positive Ch2o mean?
Body is excreting excess water
Why does the single effect have a greater effect of concentrating urine in the presence of ADH?
Because it further increases the medulla osmolarity in the TAL. This, along with ADH, further increases the drive of water out of the collecting duct and into the interstitium, which leads to the urine being more concentrated
Which diuretic is the ONLY one that decreases calcium excretion
Thiazides
What type of stone is present in RTA type 1
Calcium phosphate
What conditions typically causes calcium phosphate stones
hyperparathyroidism
What conditions typically causes calcium oxalate stones?
Hyperoxaluria.
Calciuria and oxaluria present
What conditions are typically cause uric acid stones
gout
What conditions typically cause struvite stones
UTI’s with urease bacteria present
What diuretic like response is present in barterr syndrome
Loop diuretics (TAL)
What diuretic like response is present in gitelmann syndrome
Thiazide (DCT)
What is Conn syndrome
Primary hyperaldosteronism- adrenal glands produce excess aldosterone
What is the shape of cystine kidney stones
hexagonal
ARPKD
small cysts in small people (kids)
ADPCD
large cysts in large people (adults)
Wilms tumor gene and inheritance
WT1/2, AD
Von Hippel Lindau disease gene and inheritance
VHL, AD
Tubular sclerosis gene and inheritance
TSC1/2, AD
What do calcium phosphate stones look like under microscope
Wedge shaped prisms. They look like quart crystals
What do calcium oxalate stones look like under the microscope?
Dumbell or envelope shape
WHat do struvite stones look like under the microscope?
Coffin lid. Looks like a rectangle within a rectangle
What do uric acid stones look like under the microscope?
Rhomboid, foot-ball shaped, yellowish and brown
What do cystine stones look like under the microscope?
Hexagonal (6 sides), Benzene ring
What parts of the nephron handles potassium
PCT, TAL, DCT/CD
How is potassium handled in the PCT
Passive paracellular reabsorption via electrochemical gradient
How is potassium handled in the TAL
Passive paracellular reabsorption via positive luminal potential created by NKCC co transporter
How is potassium handled in the DCT/CD
Secreted via principal cells (Na+ exchanges for K+)
Reabsorbed via alpha intercalated cells by proton-potassium exchanger
What percent of potassium is reabsorbed in the PCT
65%
What percent of potassium is reabsorbed in the TAL
25%
What percent of potassium is reabsorbed in the DCT/CD
depends on diet
What parts of the nephron handles magnesium
PCT,TAL,DCT
How is magnesium handled in the PCT
passive reabsorption parracellularly
How is magnesium handled in the TAL
Passive paracellularly due to positive luminal potential via NKCC cotransporter
How is magnesium handled in the DCT
Active transport via TPRM6 (Mag-Cal co transporter
What percent of magnesium is reabsorbed in the PCT
15-20%
What percent of magnesium is reabsorbed in the TAL
60-70%
What percent of magnesium is reabsorbed in the DCT
5-10%
What affects potasium reabsorption
Diet, aldosterone, acid-base disturbances
What part of the nephron handles phosphate
Mostly the PCT, barely the DCT or CD
How does the PCT handle phosphate?
Actively via the Na+/phosphate cotransporter
What effects PCT reabsorption of phosphate
High Phosphate= dec. reabsorption
inc PTH = dec. reabsorption
What percentage of phosphate is reabsorbed in the PCT?
70-80%
Why is glutamine so important in the kidneys (PCT/CD)
It is broken down into ammonia and bicarb via glutaminase.
Therefore creating ammonia to buffer H+ in the urine and also bicarb for reabsorption and to buffer H+ in the blood
What role does ammonia play in the TAL
It is moved into the interstitium to increase medullary osmolarity, and decrease osmolarity in the tubular lumen
What role does ammonia play in the CD
It moves into tubular lumen as ammonia to buffer H+ (turns into ammonium). This is called diffusion trap.
How does potassium levels affect ammonia production
Hypokalemia–> increases production
Hyperkalemia–> decreases production
