Kidney structure and function 2 Flashcards
Explain how the loop of Henle is involved in the absorption of water from filtrate.
At the top of the ascending limb sodium ions are actively transported out of the filtrate into the interstitial fluid at the base sodium ions diffuse out down their concentration gradient; the ascending limb is impermeable to water; in the descending limb water moves out in to the tissue, as it is permeable to water; and there is a low water potential or high concentration of ions in the interstitial fluid; The longer the loop, the lower the water potential in the interstitial fluid; Water leaves collecting duct; By osmosis, down water potential gradient.
Explain how the loop of Henle maintains a gradient of ions which allows water to be reabsorbed from the collecting duct.
Epithelial cells of tubule cells carry out active transport;
transport sodium ions out of the filtrate into the interstitial fluid; against concentration gradient; this maintains water potential gradient for water reabsorption from the descending limb and collecting duct; it is a countercurrent multiplier.
Epithelial cells of tubule cells carry out active transport;
transport sodium ions out of the filtrate into the interstitial fluid; against concentration gradient; this maintains water potential gradient for water reabsorption from the descending limb and collecting duct; it is a countercurrent multiplier.
Reabsorption of water by osmosis; At the Proximal Convoluted Tubule and descending limb of the loop of Henle; and at the Distal Convoluted Tubule and Collecting Duct concentrates urea in the filtrate.
How are the cells of the Distal convoluted tubule adapted to their function?
Microvilli to increase surface area for absorption, many mitochondria to provide ATP from aerobic respiration for active transport.
What is the role of the Distal Convoluted Tubule?
Make final adjustments to the water and salts that are reabsorbed, and the pH of the blood by selecting the ions to be reabsorbed. Is sensitive to ADH.
How is the loop of Henle and collecting duct an example of a counter current multiplier?
The filtrate in the collecting duct with a low water potential, meets interstitial fluid that has an even lower water potential. This means the water potential gradient exists for the length of the collecting duct.
How does water pass out of the collecting duct?
By osmosis, through channel proteins called aquaporins.
How can the number of aquaporins change
The Antidiuretic hormone can alter the number of channels and control water loss.
