Control of urine volume Flashcards
What controls the volume of urine produced?
It is controlled by a hormone called anti-diuretic hormone (ADH, also called vasopressin)
What is ADH also called?
vasopressin
Where is ADH produced and stored?
In a part of the brain (the hypothalamus) and stored un the pituitary gland
Where is ADH released from and into?
It is released from the pituitary gland into the blood stream
What does ADH affect?
Affects the distal convoluted tubule and the collecting duct
What does ADH caus to happen?
Causes more water to be reabsorbed from the nephron
What does ADH control?
osmoregulation (then the volume of urine produced)
When does blood plasma become too concentrated?
When we:
drink too little water
Lose too much water as sweat or faeces
Consume too much salt
What happens when blood plasma is too concentrated?
ADH travels to the kidneys. ADH causes the walls of the distal tubule and the collecting ducts to become more permeable to water.
More water is reabsorbed from the nephron.
This causes a reduction in:
salt concentration of the plasma
the volume of urine produced
When does blood plasma become normal or too dilute?
When we:
Consume a great deal of water
eat a low-salt diet
What happens when blood plasma is normal or too dilute?
ADH is not released.
the distal tubules and the collecting ducts become relatively impermeable to water.
Very little water is reabsorbed from the distal tubules and collecting ducts.
This causes:
the concentration of the plasma to remain relatively unchanged.
The production of a large volume of urine.
What are the effects of thirst/salty diet/hot day/exercise/sweating on the body:
Effect on blood:
ADH:
Distal tubule and collecting duct:
Urine:
Effect on blood: low water content and high salt concentration
ADH: Released
Distal tubule and collecting duct: More permeable to water
Urine: Low volume of water; higher salt concentration (i.e. low volume of concentrated urine)
What are the effects of excessive water intake or very low-salt diet on the body?
Effect on blood:
ADH:
Distal tubule and collecting duct:
Urine:
Effect on blood: High water content and low salt concentration
ADH: not released
Distal tubule and collecting duct: Less permeable to water
Urine: High volume of water; lower salt concentration (i.e. a high volume of dilute urine)
What are the effects of a high-protein diet on the body?
Effect on blood:
ADH:
Distal tubule and collecting duct:
Urine:
Effect on blood: normal water content and increased concentration of urea
ADH: no effect
Distal tubule and collecting duct: no effect
Urine: same volume of water; increased urea concentration (i.e. the same volume of concentrated urine)
