L54. Tubular Function - Kindey structure and filtration Flashcards
Name the 4 layers through which reabsorption and secretion occur.
Tubule lumen, tubule wall, interstitial space, peritubular capillary.
-> reabsorption
Name substances which are and are not reabsorbed in the kidneys.
Glucose, water and amino acids are reabsorbed.
Creatinine is not - it is freely filtered but not absorbed. it can be used to measure glomerular filtration rate.
What do aquaporins do?
Allow water to move down a conc gradient
Describe the limbs of henle.
(all in the medulla)
Thin descending limb
Thin ascending limb
Thick ascending limb (heading towards cortex)
What feature is present in the thin descending limb?
Contains aquaporins - permeable to water
Name a feature of the thin ascending limb.
No aquaporins - impermeable to water
Name a feature of the thick ascending limb.
No aquaporins.
Site of active sodium reabsorption (sodium moves out)
Describe countercurrent multiplication.
As more water is pumped out of the LHS of the loop of henle, the RHS’s high salt conc reacts by pumping salt out into the interstitium (medulla). This is a constant cycle of increased and decreased concentrations.
What are the vasa-recta capillaries?
Long hairpin-shaped blood vessels which run parallel to the loop of henle. The turns slow blood flow which helps maintain the osmotic gradient.
What happens in the distal convoluted tubule?
Site of fluid volume and electrolyte regulation.
Name 3 hormones which regulate Na+ and H20 reabsorption.
ADH (increases water reabsorption)
ANH (promotes Na+ secretion)
Aldosterone (increases Na+ reabsorption)
What does ANH inhibit?
ADH and aldosterone to produce a large volume of dilute urine.
Name the general rule for filtration.
everything follows sodium
What is secondary active transport?
When energy is provided after the action.
