the

How the Body Corrects Concentration Changes - Thirst and ADH

so this is how the brain senses changes

in concentration and now how does the

body correct those changes well it does

so in two ways so the first way that the

body corrects changes in concentration

is by changing the amount of water that

you drink

so it'll affect thirst and how does this

happen

well we already have an osmolar scepter

here in the brain that's been activated

by the change in concentration so it

just sends a signal to another nearby

part of the brain that causes you to

become more thirsty and the second way

that you correct your change in

concentration is to change the amount of

water that your kidneys are excreting

and the way that this works is that you

have some ozma receptor here in the

hypothalamus that's been activated and

it actually secretes a hormone into

circulation so it secretes a hormone

which is called anti diuretic hormone

often abbreviated ADH but it actually

has many names sometimes instead of ADH

it's called vaso pressin sometimes it's

even called a third name which is

arginine vaso pressin or even arginine

vasopressin peptide which can be

abbreviated a V P so it's kind of

irritating there are so many names but

just try to remember that these are all

the same thing and you should know that

these Osmo receptors project it down

into this little part of the brain which

has a name as well this is called the

posterior pituitary and it's a gland we

call it a gland because it secretes

stuff what does it secrete well one of

the things is this ADH so the posterior

pituitary and gland so at the posterior

pituitary gland ADH is secreted into

circulation so let's put it in a little

blood vessel there and then it goes all

the way through systemic circulation and

eventually makes its way to the kidney

and that's where it has its effect to

change water excretion so these are all

the details that you need to know the

overall picture here is the brain is

sensing changes in concentration and

then it's going to correct them by

changing your thirst and changing your

water excretion and to be a little more

specific let's say you had an increase

in concentration what's that going to do

that's going to cause a increase in

thirst because you want to take in more

water to offset that concentration rise

and a decrease in water excretion and on

the other hand a decrease in

concentration is going to cause a

decrease in thirst so that you don't

dilute your fluids even more and an

increase in water excretion so that you

can raise your concentration back to

normal levels now the last thing I want

to mention this video is getting long

and intense

but ADH causes decreased water excretion

so when you have a rise in your

concentration you're gonna want to

reduce your water excretion and you do

that by increasing your ADH whereas here

when you have a drop in concentration

you want to excrete more water and you

do that by secreting less ADH