Flashcards in Handling Sodium And Hypertension Deck (86)
What is the most osmotically effective solute in the ECF?
The input and output of Na+ is approximately how much per day?
How is Na+ lost from the body?
What is the osmotic status of sweat?
In which part of the nephron can we control how much Na+ is reabsorbed?
What percentage of sodium is reabsorbed in the PCT?
How will changes in the peritubular capillaries affect the PCT Na+ reabsorption?
Decreased pressure in capillaries = increased reabsorption
Increased pressure in capillaries = decreased reabsorption
Describe what happens to Na+ reabsorption when renal BP increases
Decreased Na-H antiporter and reduced ATPase activity
Decreased Na+ reabsorption in PCT
Decreased water reabsorption in PCT
ECF volume decreases
How is Cl- reabsorbed?
Coupled to pumps and dependent of Na+
What percentage of bicarbonate is reabsorbed in the PCT?
What percentage of Cl- is reabsorbed in the PCT?
Which sodium transporters are present in the PCT?
Which sodium transporter is present in the loop of Henle?
Which sodium transporter is present in the early DCT?
Which sodium transporter is present in the late DCT and CD?
Which molecules are reabsorbed up to 100% in the PCT?
What is the order of molecules reabsorbed as you travel down the PCT?
First = glucose, amino acids, lactate
Second = bicarbonate
Third = phosphate
Fourth = chloride
How is the PCT divided?
S1, S2, S3
Describe the glomerulotubular balance
Autoregulation - blunts Na+ excretion in response to GFR changes
Always try to take 67% of whatever is filtered
Higher GFR -> more reabsorption
How come the PCT can regulate how much Na+ it reabsorbs?
Because the PCT has flexibility due to not using all of its transporters all of the time
What is the equation for filtered load?
Filtered load = GFR x concentration
What is the osmotic status of the filtrate at the bottom of the loop?
Hypertonic in comparison to plasma
How does Na+ reabsorption occur in the thin ascending limb?
Relies on the steep gradient of Na+ conc to drive passive reabsorption of Na+
How does Na+ reabsorption occur in the thick ascending limb?
What does NKCC2 move?
Na+, K+ and 2Cl- from filtrate into cells
What happens to the ions that pass through NKCC2?
Na+ pumped into interstitium via ATPase
K+ diffuses via ROMK back into the tubule
Cl- diffuses into the interstitium
Which region of the nephron is particularly sensitive to hypoxia?
Thick ascending limb of loop of Henle
Uses the most energy
What is the osmotic status of filtrate leaving the loop of Henle?
Hypo-osmotic in comparison to plasma
Why is the filtrate further diluted in the DCT?
Because active Na+ reabsorption can occur but the water permeability of the DCT is fairly low so water cannot follow