Homeostasis And The Kidney Flashcards
Where does Selective Reabsorption take place
The proximal convoluted tubule
How and where are substances selectively reabsorbed to
Water by osmosis into adjacent blood capillaries
Ions partly by diffusion or active transport
Glucose and amino acids by active transport into the blood
Small proteins by pinocytosis
What level is the filtrate at by the end of the PCT
The filtrate is isotonic in the plasma
How is the large surface area maintained in the PCT
Numerous microvilli and unfolding of the basal cell-surface membrane
What occurs to ions in the loop of Henle
Sodium and chloride ions pass out of the ascending limbs by diffusion and active transport into the surrounding tissue of the medulla
What occurs in the descending limb of the loop of Henle
An osmotic gradient due to lack of ions is created, so water draws out of the limb to be carried by blood to surrounding capillaries
What is the difference of fluid level in the descending limb to the ascending limb
The fluid is saltier going down the descending limb, and is less salty as it goes up the ascending limb
How does reabsorption occur in the DCT
The ionic composition and the pH of blood are adjusted
What is reabsorption
When useful substances come back into the blood and occurs as the filtrate as is passed along the nephron and collecting duct
Where is ADH produced, and then secreted
The hypothalamus, into the posterior lobe of the pituitary body
What does a rise in blood concentration do to level of ADH in the blood
Osmoreceptors send impulses to the posterior lobe of the pituitary gland which causes the related of more ADH to increases the permeability of water of the DCT and collecting duct
What does a fall in blood concentration do to ADH concentration in the blood
It inhibits the release of ADH so the walls of the DCT becomes impermeable to water
Why is the negative feedback system negative
An increase in water potential will later result in a decrease in water potential
