Tubular Reabsorption & Secretion(B)- Exam 3 Flashcards
What percent of filtered load of sodium and water is reabsorbed in the proximal tubule?
65% (little less percentage for chloride; quantity can be increased or decreased as needed)
What are the cells of the proximal tubule designed for?
High reabsorption capacity of sodium and water
What supports the extensive active transport activity in the proximal tubule?
Contains a large number of mitochondria
What provides a huge surface area for rapid diffusion in the proximal tubule?
Luminal (apical) brush border
What contains extensive number channels in between cells providing huge surface area?
Basolateral border
What contains extensive number of protein carrier molecules in the proximal tubule?
Luminal border
Why is there an extensive number of protein carrier molecules in the proximal tubule?
Co-transport of amino acids and glucose
Counter-transport of hydrogen ions (move a large quantity of hydrogen ions against small hydrogen ion gradient)
What contains an extensive amount of N/K ATPase in the proximal tubule?
Basolateral border
What is notable about the first half of the proximal tubule?
- Extensive co-transport of sodium with glucose and amino acids
- Sodium reabsorption carries glucose, bicarb, organic ions leaving chloride resulting in increasing [Cl-]
What is the change in [Cl-] in the early part of the proximal tubule?
105 mEq/L increases to 140 mEq/L
What is notable about the second half of the proximal tubule?
- High chloride concentration favors chloride diffusion (some movement thru Cl- channels)
- Most glucose and amino acids have been reabsorbed; sodium reabsorption drives chloride reabsorption (electrochemical gradient)
What changes (quantity/concentration) in the tubule throughout the reabsorption process?
Quantity of sodium in tubule changes, but concentration does not change because water reabsorption matches sodium reabsorption
Does osmolarity change during reabsorption?
No, water reabsorption matches sodium reabsorption
What happens to glucose and amino acid concentrations as they move through the tubules?
Decrease due to extensive reasborption
What happens to creatinine and urea concentrations as they move through the tubule?
they become more concentrated because they are not reabsorbed
Total amount of Na+, Cl-, HCO3-, glucose, amino acids in tubules ________(increase/decrease/does not change).
Decrease; but Cl- concentration goes up as were in the second half of the proximal tubule
Total amount of creatinine and urea in tubule _________(increase/decrease/does not change)
Does not change
What end products of metabolism are secreted by the proximal tubule?
Bile salts
Oxalate
Urate
Various catecholamines
What drugs and toxins are secreted?
Penicillin
Salicylates
What other acid is also secreted?
Para-aminohippuric acid (PAH)
What percent of PAH in the renal blood flow is removed?
90%
How can you use PAH to determine renal blood flow?
Knowing that 90% of PAH in renal blood flow is removed
What are the three functional segments of hte loop of henle?
Thin descending segment
Thin ascending segment
Thick ascending segment
What kind of membrane/characteristics does the thin descending and ascending segments have?
Thin epithelial membrane
(No brush border)
Few mitochondria (not a lot of active transport)
Minimal metabolic level