The Kidney - Osmoregulation Flashcards
What does ADH stand for
Anti-diuretic hormone
What controls water potential
Hypothalamus
Osmoreceptor neurones
Antierior pituitary glans
ADH
WHat process controls water potential of body fluids
Osmoregulation
What monitors water potential of the blood
Osmoreceptors
How do osmoreceptors control water potential (detecting change)
Osmoreceptors found in the hypothalamus
Detect a decrease in water potential of the blood, verve impulses are sent along sensory neurones to the posterior pituitary gland
How do osmoreceptors control water potential of the blood (after detecting the change)
Nerve impulses stimulate the posterior pituitary gland to release antidiuretic hormone (ADH)
ADH enter the blood and travel throughout the body
What does ADH do to control water potential
ADH is released in the posterior pituitary gland which causes the kidneys to reabsorb more water to reduce the loss of water in the urine
Is osmoregulation positive or negative feedback
Negative
How does osmoregulation detect change detail
1) Osmo-receptor cells in hypothalamus lose water by osmosis and shrink (osmosis is high to low concentration of water, high water potential in blood causes water in cells to leave via osmosis)
2) This stimulated neuro-secretory cells to produce more ADH from the posterior pituitary gland
How does ADH control water potential in detail
1) ADH travels to kidney and acts on collecting ducts in the kidney that increases aquaporins that are inserted into the cell surface membrane in the collecting duct so water can enter the bloodstream
2) Urine is therefore produced with a lesser water potential
Negative feedback of water potential in blood when water potential is high
1) Hypothalamus detects high blood water potential
2) Pituitary secretes less ADH
3) Aquaporin channels close
4) Less water is reabsorbed from urine
5) Water potential brought back up to normal
Negative feedback of water potential in blood when too low
1) Hypothalamus detects low blood water potential
2) Pituitary secretes more ADH
3) ADH increases production of cAMP
4) cAMP increases the number of aquaporins
5) More water is reabsorbed from the urine
6) Water potential of blood is brought back up to normal
What molecules affect blood glucose concentration
Insulin
Glucagon
Adrenaline
How does insulin, glucagon and adrenaline affects blood glucose concentration control
Insulin = decereases blood conc of glucose if too high
Glucagon = increases
Adrenaline = increases
How does insulin reduce glucose in blood
Convert glucose into glycogen
Put it in muscles
Break down glucose and use it
Make it into fats
What is water potential monitored by
Osmo-receptors in the hypothalamus of the brain
How ADH affects water reabsorption in the collecting duct of the nephron
1) ADH binds to receptor proteins in the cell surface membranes of the collecting duct cells
2) Aquaporins are phosphorylated (number increases)
3) Vesicles (with aquaporin-containing membranes) move towards luminal membranes of collecting duct cells so water can leave more easily into the bloodstream
4) Vesicles fuse with luminal membranes
5) Water moves through aquaporines down the water potential gradient into the concentration tissue fluid and blood plasma in the medulla of the kidney
Process of what happens if the water potential of the blood is too high
1) Osmoreceptors in the hypothalamus are not stimulated
2) no nerve impulses are sent to the posterior pituitary gland
3) No ADH released
4) Aquaporins are moved out of the luminal membranes of the collecting duct cells
5) The filtrate flows along collecting duct but loses no water and is very dilute
6) A large volume of dilute urine is proeduced
7) This flows from the kidneys through the ureters into the bladder
Glycogenesis and Glycogenolysis
Glycogenesis = glucose -> glycogen
Glycogenolysis = Glycogen -> glucose
What are the three ways glucose can enter the bloodstream
1) absorption in the gut following carbohydrate digestion
2) Hydrolysis of glycogen stores
3) Non-carbohydrates converted to glucose (lipids, amino acids)
What happens if the water potential of blood is too high
1) Osmoreceptors in hypothalamus not stimulated
2) No nerve impulses sent to the posterior pituitary gland
3) No ADH is released
4) Aquaporins are moved out of the luminal membranes of the collecting duct cells
5) Collecting duct cells are no longer permeable to water
6) The filtrate flows along the collecting duct without losing water because its very dilute
7) A large volume of dilute urine is produced
8) The urine flows from the kidneys through ureters into the bladder
What does ADH control
How many ions are being pumped out (sodium ions)
Increasing sodium ions being pumped out makes water filter into bloodstream more, making urine more dilute and less
What monitors the water potential of blood
Osmo-receptors in the hypothalamus of the brain
Summary of what happens when water potential of the blood is too low IN BRAIN
ADH increases
Osmo-receptors in hypothalamus lose water by osmosis so they shrink stimulating the neuro-secretory cells to produce more ADH from posterior pituitary gland
What happens ot the collecting duct in the presence of adh
ADH arrives at kidney and binds to cell surface receptors in the cells that line the collecting duct. This triggers a series of enzyme controlled reactions.
Aquaporins are inserted into the cell surface membrane to make the wall permeable to water
Water reabsorbed by osmosis into blood produces urine of lesser water potential and more concentrated urine
What are aquaporins
Water permeable channels
What happens to the collecting duct in the absence of adh
Cells surface membranes fold inwards removing water permeable channels
Less water is reabsorbed by osmosis into blood
More dilute urine produced
Describe the negative feedback loop of when blood water potential is HIGH
1) Hypothalamus detects high blood water potential
2) Pituitary secretes less ADH
3) Aquaporin channels close
4) Less water is reabsorbed from urine
5) Normal blood water potential
Describe the negative feedback loop of when blood water potential is too low
1) Hypothalamus detects low blood water potential
2) Pituitary secretes more ADH
3) ADH increases production of cAMP
4) cAMP increases the number of aquaporins
5) More water is reabsorbed from urine
6) Back to normal blood water potential
Process of how ADH affects water reabsorption in the collecting duct of the nephron
1) ADH binds to receptor proteins in the cell surface mmebranes of the collecting duct cells
2) Aquaporins are phosphorylated
3) Vesicles move towards luminal membranes of collecting duct cells
4) Vesicles fuse with luminal membranes
5) Water moves through aquaporins down the water potential gradient into the concentrated tissue fluid and blood plasma in the medulla of the kidney
WHat hapens if water potential in the blood is too high
1) Osmoreceptors in hypothalamus not stimulated
2) No nerve impulses are sent to the posterior pituitary gland
3) No ADH released
4) Aquaporins moved out of the luminal membranes of the collecting duct
5) Collecting duct cells impermeable to water
6) Filtrate flows along collecting duct but no water is lost
7) Dilute urine produced
How does ADH affect urine
1) Permeability of membrane is increased
2) More water absorbed by collecting duct and distal tubule
3) Smaller volume of urine
4) Urine more concentrated
