Kidney Flashcards
What parts of the kidney are responsible for ultrafiltration?
The glomerulus and Bowman’s capsule
What is the function of the proximal convoluted tubule?
Reabsorption of glucose, amino acid, minerals & hormones back into the blood
What is the function of the loop of Henle?
Makes the medulla more concentrated than the cortex via the countercurrent multiplier
What is the function of the distal convoluted tubule?
Reabsorption of ions and water
What is the function of the collecting duct?
Fine tuning of water concentration in urine
What is responsible for detecting low water levels in the blood?
Osmoreceptors in the hypothalamus
What happens once osmoreceptors detect low water potential in the blood?
Triggers the secretion of ADH from the pituitary gland
How does ADH reach the collecting duct from the pituitary gland?
ADH is a hormone that travels in the blood to the collecting duct
What does ADH do once it reaches the collecting duct, and what is the result of this?
ADH binds to receptors on the cell surface of collecting duct cells, which activates cAMP
What does cAMP do in collecting duct cells?
It causes vesicles containing aquaporins to fuse with the membrane, meaning aquaporins are inserted into the collecting duct membrane
What are aquaporins?
Membrane water channels that allow for the transport of water across the collecting duct membrane
What is the result of an increased number of aquaporins in the collecting duct tubule?
Water will leave the collecting duct tubule into tissue fluid, and will eventually renter the blood via osmosis, conserving water in the body
What happens when there is an excess of water in the body?
The secretion of ADH is inhibited, so cAMP levels also fall, causing aquaporins to be removed from the tubule, meaning more water remains in urine to be rid of
