The kidneys

what is the importance of water regulation in the body?

cells lose or gain water through osmosis too much means the cell may burst and too little means the cell will shrivel

how do we lose water?

From the skin in sweat and from the lungs when breathing out

what is deamination?

the process through which the liver converts excess amino acids into ammonia, however ammonia is toxic so is immediately converted to urea for excretion

what is selective reabsorption?

When useful molecules are absorbed back into the blood, other molecules are left in the tubule and all the molecules/waste left over is what forms urine

what are the three functions of the kidneys?

- remove waste products from the blood/body
- regulate ion levels
- regulate water levels

how do small substances such as urea get forced out of the blood during filtration

as a result of high pressure mass flow of blood, they don’t diffuse out of the blood

is only some or all of the glucose reabsorbed during selective reabsorption

all of the glucose

what happens when water levels are too low?

- the hypothalamus detects the conc of water in the bloodstream and sends a signal to the pituitary gland to release a hormone called ADH then, this makes the kidney tubules more permeable, so they absorb more water during selective reabsorption (hence why when you don't drink a lot of water your wee is more yellow as there's more urea in the urine)

what happens when the water levels are too high?

the hypothalamus detects the conc of water in the bloodstream and stops sending signals to the pituitary gland, so it won't release as much ADH so the kidney tubules become less permeable and so reabsorb less water during selective reabsorption and so the urine is more dilute