T3 L4: Formation of urine 2 Flashcards
What happens in the descending limb of the loop of Henle?
Extraction of water
What happens in the ascending limb of the loop of Henle?
Extraction of Na+ and Cl-
Describe the cells in the thin descending limb of the loop of Henle
Flat cells because there’s no active transport of salts. Freely permeable to water via AQP1
Describe the cells in the thick ascending limb of the loop of Henle
Tubular cells, impermeable to water. Have specialised Na+/K+/2Cl- (NKCC2) co-transporters
What is osmolality?
The measure of concentrations based on dissolved solutes measured as osmoles per litre
What is countercurrant multiplication in the kidneys?
Salts from the thicker ascending loH leave and attract water to go outside the thin descending loH which allows the reabsorption of water from the descending loH. Its facilitated by NKCC2
What role does urea have in the countercurract multiplication of the kidneys?
It diffuses out of the collecting duct and goes into the medulla down its concentration gradient and adds to the osmolality of the medullary interstitium
Where is urea reabsorbed?
In the proximal tubule
What are the structures in order that tubular fluid goes through in a nephron?
- glomerulous
- proximal tubule
- loop of Henle
- distal tubule
- collecting duct
What happens in the distal tubule?
Active absorption and secretion of solutes. Na+ and Cl- are actively reabsorbed in exchange for K+ and H+ which are secreted into the tubular fluid
What are principal cells, what do they do and what controls them?
Aldosterone makes them reabsorb Na+ and push K+ out in the distal tubule
What do macula densa cells do?
They sense Na+
Where is aldosterone released from?
Adrenal glands
How does aldosterone affect blood pressure?
Aldosterone causes principle cells to reabsorb Na+ so more water moves into the plasma and BP increases
What do intercalated cells do?
They exchange Na+ for H+ in the distal tubule and early collecting duct
