Mangiarua - Na Water Transport Flashcards
the sodium movement across the luminal membrane is alway ____
Downhill
The major site for reabsorption of water and salt?
The proximal tubule
What happens to reabsorption when there are changes in GFR?
The proximal tubule reasorbs a constant FRaction of filtered fluid. But overall load decreases
Increased urine flow that is due to extra amount of non-reabsorbed solute within the tubular lumen
Can be caused by mannitol
Occurs in severe diabetes
Osmotic diuresis
Location in the nephron which reabsorbs approximately 25% of the filtered sodium and chloride and roughly 15% of the filtered water
Loop of Henle
Mechanism of action for furosemide and betemanide ?
Inhibition of the Na-K-2Cl symptorters in the thick ascending limb of the loop of Henle
What percentage of filtered sodium and chloride ions reach the distal tubule ?
10%
What percentage of filtered water reaches the distal tubule
20%
What is the target for inhibition of thiazide diuretics?
NaCl symporter in the distal convoluted tubule
caused by mutations in the gene that codes for the epithelial sodium channel (ENaC) in the principal cells of the collecting duct system inducing excess Na+ reabsorption. It is characterized by early, and severe hypertension associated with low plasma renin activity, metabolic alkalosis due to hypokalemia, and hypoaldosteronism.
Liddle’s Syndrome
caused by mutations in the gene that codes for the Na-Cl cotransporter in the distal tubule. It is characterized by increased excretion of Na+, Mg2+, Cl-, and K+.
Gitelman’s Syndrome
caused by mutations of genes encoding proteins that transport ions in the thick ascending limb of the nephron, including the Na-K-2Cl cotransporter, the K+ channel, and the Cl- channel. It is characterized by very large urinary losses of NaCl, hypokalemia. Ca2+ and Mg2+ wasting may also occur.
Bartter’s Syndrome
The minimal amount of water that we must excrete each day in order to dissolve the solutes that our body must excrete
Obligatory water loss
0.43L/day
The function of the loop countercurrent multiplier system is to ?
Increase the osmotic concentration of the medullary interstitium
The descending limb of the loop of henle reabasorbs _____
Water
The ascending limb of the loop of Henle reabsorbs _____
Na
Cl
In antidiuresis, there is a _____ osmolarity of the medulla and papillae that are due to urea reabsorbed between the medullary collecting duct and ascending loop of henle
High
40-50%
In diuresis, there is a ______ permeability of the medullary collecting duct
Low
Only 10% of interstital osmolarity is due to urea
“Water free of solutes” is generated in the _____
Ascending limb of the loop of henle
Way to quantify the rate of excretion of total solute
Osmolal clearance
Compares the rate of solute excretion w/ the rate of water excretion
Free water clearance
Free water clearance > 0 when ….
Uosm is less than Posm
Urine is more dilute
Free water is being lost
You are concentrating the plasm
Hydropenia
Fluid restriction
Regardless of availability of fluid, a person must excrete ate least ______ mOsm/min
0.5-1.0
Urine flow that is greater than normal
In excess of 1mL/min in adult human
Diuresis
Increased urine flow that is due to extra amount of non-reabsorbed solute within the tubular lumen
(Can be caused by mannitol)
Osmotic diuresis
Increased urine flow due to decreased reabsorption of “free” water
Occurs in persons who have drunk a large amount of dilute fluid
Also occurs in patients w/ diabetes insipidus
Water diuresis
Urine flow that is less than normal, usually below 0.5 mL / min in adult human
Antidiuresis
