B12.3 The human kidney Flashcards
Where is the urine stored?
In the bladder
What does the kidney filter?
Glucose
Mineral ions
Urea
Water
What is the purpose of the renal artery?
Brings blood containing urea and other substances in solution to the kidney
What is the purpose of the renal vein?
Carries blood away from the kidney after urea and other substances have been removed
What is selective reabsorption?
Where the amount of water and dissolved mineral ions are reabsorbed varies as it depends on what is needed by your body
What does a healthy kidney do?
Produces urine by filtering the blood - then reabsorbs all of the glucose + any mineral ions and water
What is the kidney made up of?
Tiny tubules - it is along these tubules that selective reabsorption of water and mineral ions takes place
How is the amount of water in the blood maintained?
By a negative feedback system involving the hormone ADH
Where is ADH secreted from?
The pituitary gland
How is the concentration of solutes in the blood plasma detected?
By receptor cells in the brain
What happens if the blood becomes too concentrated?
Pituitary gland releases lots of ADH.
This affects the tubules so they reabsorb much more water - leads to small volume of very concentrated urine and the concentration of solutes in the blood returns to normal
What happens if the solute concentration becomes dilute?
Less ADH is released into the blood.
Less water is reabsorbed in the kidney tubules - so you produce a large volume of dilute urine and the blood solute concentration returns to normal
What happens on a hot day if you drink little and do a lot of exercise?
Lose a lot of water in your sweat and produce very little urine - will be concentrated and dark yellow
What happens on a cool day with excess liquid?
Produce dilute almost colourless urine
Why does the kidney work hard after you eaten a lot of salty processed food on a hot day?
Salt affects the concentration of body fluids, the balance of which must be maintained for optimal cell function.
The kidney is involved in balancing the body’s salt levels.
If salt levels go up, kidneys remove salt and excrete it in urine.
A hot day will cause a lot of uncontrolled water loss through sweating, so kidneys will need to conserve water as well as remove excess salt.
