Gene Models & Nephron Function III Flashcards
What do the connecting tubules connect
late distal tubule to cortical collecting duct
What are the two cell types in the late distal tubule
principal, intercalated
What is secreted in the Late distal tubule and collecting duct
K+ and H+
What do the principal cells reabsorb
Na+, H2O
What do the principal cells secrete
K+, H+
What are the two types of intercalated cells
alpha and beta
What is secreted/reabsorbed in the intercalated
H+ and HCO3- are secreted and reabsorbed
What channels are on the apical side of the principal cells
ENaC, ROMK, Aquaporin 2
What channels are on the basolateral side of the principal cells
Kir2.3, AQP3, AQP4, sodium potassium ATPase
What is the function of the principal cell
regulation of urine composition
What is the function of Kir2.3
maintain negative membrane potential, and low intracellular sodium conc
What regulates ENaC in the principal cell
signalling pathways - phosphorylation
What does reabsorption of sodium in the principal cell drive
potassium secretion
Which channels are not regulated in the principal cell
AQP3, AQP4
What does the number of AQP2 channels depend on
fluid in the body
What is the rate limiting step for water reabsorption across the collecting duct
AQP2
What steps up the driving force for water reabsorpion
high conc of sodium and potassium in interstitial fluid
Name some diseases of the principal cells
Diabetes insipidus, Liddle’s syndrome, Pseudohypoaldosteronism
What are the symptoms of diabetes insipidus
problems concentrating the urine
What channel is affected in diabetes insipidus
AQP2
What channel is affected in Liddle’s syndrome
ENaC
Describe symptoms of Liddle’s syndrome
hypertension, too much reabsorption of sodium and water
What do the symptoms of pseudohypoaldosteronism mimic
low levels of hormone aldosterone
What is amiloride
potassium sparing diuretic
What does amiloride block
ENaC, sodium and water reabsorption
What does amiloride target
principal cells
What does amiloride treat
high BP
TRUE or FALSE - alpha intercalated cells have a proton pump on the apical membrane
True
What is the function of the proton pump in the alpha intercalated cell
hydrolyse ATP - pump hydrogen ions out against conc grad
What channels are located on the basolateral membrane of the apical intercalated cell
halogen ion channel - AE1, chloride channel
What is the function of the chloride channel in the alpha intercalated cell
recycling of chloride across basolateral membrane
What is the function of AE1 in the alpha intercalated cell
moves bicarbonate out - reabsorbed
Why is reabsorption of bicarbonate important
regulation of body fluid pH
What disease is associated with alpha intercalated cells
distal renal tubular acidosis
What causes distal renal tubular acidosis
mutation in AE1 - basolateral membrane
What happens to cells when AE1 is mutated
AE1 appears on both membranes - bicarbonate is lost
What are the symptoms of distal renal tubular acidosis
metabolic acidosis, low body fluid pH, renal damage, nephrocalcinosis
Describe the permeability of the medullary collecting duct
high permeability to water, urea, low sodium permeability
When is the medullary collecting duct permeable to water and urea
in the presence of vasopressin
What are the symptoms of acute renal failure
fall in glomerular filtration rate, accumulation of urea, creatinine
How is acute renal failure treated
dialysis
TRUE or FALSE - acute renal failure is irreversible
FALSE
What are the symptoms of acute renal failure
hypervolalemia, hyperkalaemia, acidosis, high urea/creatinine
What is hypervolaemia
oliguria due to low GFR
What does hyperkalaemia cause in acute renal failure
cardiac excitability, risk of cardiac death
