7.20: ADH regulates water content of the blood

What does ADH stand for?

Anti-diuretic hormone

What is a diuretic?

Something that makes you wee

What is an anti-diuretic?

Something that makes you wee less

Where is ADH released from?

The pituitary gland

How does ADH reach the kidneys?

Through the bloodstream

Is more or less ADH released when water potential is high (the water content of the blood)?

Less ADH, which makes you wee more

How does ADH work?

Having a high concentration of ADH in the blood increases the permeability of the collecting duct, so that less water can be reabsorbed into the blood and less is released through urination

What is the impact of ADH being released on urine?

Urine has a higher concentration of urea and less is released (a lower volume)

If someone is working out on a hot day, what is their urine like?

Their urine will be concentrated and of a low volume since their body doesn’t have enough water, so it needs to recycle it within the body - to do this, the pituitary gland released ADH to make the collecting duct more permeable (so more water is reused in the body) and a lower concentration of water can leave the body. The reason the body is dehydrated is because it is both a hot day (causing more water to be released through sweating and water vapour from breathing and speaking) and the person is exercising (so they are losing more water through sweating more)

What is ADH an example of?

A negative feedback loop

What is the aim of this negative feedback loop?

Keep the concentration of the blood plasma constant as the conditions are continually changing from the ideal, so hormones are released/inhibited to return these changes back to the ideal point