Water regulation

1.

WATER REGULATION

2.

Lesson objectives
To explain the role of antidiuretic
hormone (ADH) in water regulation.

3.

Lets think!
Why do human feel thirsty?

4.

What is homeostasis?
Homeostasis is internal balance of the
body.
Body needs certain conditions to function
properly.
Ex: body temperature, salt concentration,
water amount, blood pH etc.

5.

What is osmoregulation?
Water balance influence on salt balance
because salts and many other substances
are dissolved in water.
Osmoregulation is maintaining balance
between water and solutes.

6.

Maintaining osmoregulation
Osmoregulation is related with excretion.
If body has too much water salt
concentration will fall. In that case urine
that is excreted will be dilute, containing
large amount of water.
If the body has a little amount of water urine
will be concentrated, containing a little
amount of water.

7.

Regulation of urine concentration
Urine concentration is regulated by water
reabsorption.

8.

Regulation of water reabsorption
Water reabsorption is regulated by
osmoreceptors in brain. They are sensitive
to increase of solute concentration.

9.

If solute concentration balance
increases hypothalamus sends signal
to pituitary gland.
Then pituitary gland produce ADH
(vasopressin).
ADH target is collecting duct of
nephron.
ADH increases permeability of
water in collecting duct by increasing
aquaporin number so it reabsorbs
more water and urine will be
concentrated.
When salt concentration is stabilized
osmoreceptors stop sending signals
to pituitary which stops to produce
ADH, so kidneys reabsorb less
water.

10.

11.

Failure of ADH production:
Hyperfunction of ADH
2. Hypofunction of ADH
1.

12.

Hyperfunction of ADH
Excess production of ADH is called
hyperfunction of ADH.
Hyperfunction of ADH causes SIADH
(Syndrome of Inappropriate Antidiuretic
Hormone).
SIADH causes dilute blood and
concentrated urine.

13.

Causes of hyperfunction of ADH
Drug side effects
Lung disease
Hypothalamus and pituitary disease
Cancer

14.

Hypofunction of ADH
Hypofunction of ADH is insufficient
production of ADH.
Hypofunction of ADH causes kidneys to
excrete too much water, dilute urine,
dehydration, drop in blood pressure.
It can cause diabetes insipidus. Its
symptoms are high level of thirst and
urine excretion.

15.

Causes of hypofunction of ADH
Hypothalamus and pituitary damage
Polydipsia (excess water drinking)
Tumor
Trauma

16.

Let’s do the activity on p. 87

17.

Homework
Read p. 86-87
Answer to literacy questions on p 87.
New words