Unit 4 - Renal Tubule Flashcards
What plays a crucial role in maintaining ionic concentration
Na+/K+ ATPase
Where are the Na+/K+ ATPase pumps located in the renal tubule?
On the basolateral membrane
How many sodium and potassium ions are exchanged in a Na+/K+ ATPase?
- three Na+ ions are moved in
- two K+ ions are moved in
What is created by the Na+/K+ ATPase?
- low intracellular sodium concentration
- negative charge intracellularly
What is formed by the negative intracellular charge created by the Na+/K+ ATPase?
Electrochemical force from the lumen to the interstitium
What is allowed to flow through a transporter from the tubule into the cell down a concentration gradient?
Na+
Movement of anions coupled to the movement of sodium
How much of the solute-laden filtrate is reclaimed in the proximal tubule?
60 - 80%
What volume of fluid is filtered across the glomerulus daily?
180 litres
What volume of the 180 litres of fluid filtered through the glomerulus reaches the distal tubular elements?
50 litres
- 130 litres of fluid is reabsorbed
Which molecules are involved in the reabsorption process in the proximal tubule?
- sodium
- chloride
- bicarbonate
- phosphate
- glucose
What percentage of the filtered NaHCO3 is absorbed in the proximal tubule?
80%
What percentage of the filtered NaCl is absorbed in the proximal tubule?
50%
Which part of the kidney reabsorbs >90% glomerular filtrate?
Nephron
What proportion of glomerular filtrate is absorbed in the proximal tubule?
2/3
What proportion of glomerular filtrate is absorbed in the distal tubule?
1/3
Which part of the nephron has few mitochondria and little Na+/K+ ATPase?
Descending limb
What is the consequence of the descending limb having few mitochondria and little Na+/K+ATPase?
Not active methods for reabsorption
What is the descending limb highly porous to?
- water
- urea
Why is the descending limb highly porous to water and urea?
Cells are leaky
- lack of tight junction
Abundant aquaporin I channels
What volume of the 60 litres of filtrate that enters the descending limb is reabsorbed?
30 litres
How does the concentration of the filtrate in the descending limb change?
Goes from isotonic to hypertonic
Isotonic solutions are two solutions that have the same concentration of a solute. Hypertonic solution. Hypertonic solution is one of two solutions that has a higher concentration of a solute.
What percentage of particles that enter the ascending limb are reabsorbed?
75%
Why is there a high density of Na+/K+ATPase in the ascending limb of the nephron?
High energy requirement
- lots of active reabsorption
Why is the ascending limb highly susceptible to injury through hypoperfusion or hypoxia?
High energy requirement
- lots of oxygen needed for ATPase
