role of hormones

1. ROLE OF HORMONES
IN
EXCRETION
M.RAJKUMAR.M.sc,M.Ph
il
Periyar University,

2. What is excretion?
 Excretion in Physiology is the process
of elimination of metabolic wastes and
other toxic substances from the body.

3. Nitrogen wastes?
 Nitrogen wastes are residuals derived
from the degradation of proteins.
 These are ( major ) :
1. Ammonia
2. Urea
3. Uric acid

4. AMMONIA (NH3)
 Ammonia is formed by the
deaminatated of amino acids .
 Its very toxic and it should be
eliminated immediately.
 This process requires very little
energy.
 Ammonia is highly soluble in water.
NH3 + H2O -- NH4 OH
(ammonium hydroxide)

5.  Aquatic animals such as bony fishes,
aquatic invertebrates, and amphibians
excrete ammonia because it is easily
dissolved in the water.
The animals excreting ammonia are
called ammonotelic animals .

6. * Its derived from ammonia through
ornithine cycle.
* Its less toxic and more soluble in water
when compared to ammonia .
* Its excreted by semiterrestrial animals .
* The animals excreting urea are called
ureotelic animals.
Eg : Earthworms , amphibians , semi
terrestrial turtles , mammals , etc…
UREA

7. URIC ACID
 its less toxic and insoluble in water .
Its excreted out as thick pastes or
pellets.
 Its excreted by true terrestrial
vertebrates.
 Reptiles and birds eliminate uric acid .
 The white material seen in bird
droppings is uric acid.
 The animals excreting uric acid are
called uricotelic animals.

9. * The excretory system is formed of
kidneys (two), ureters (two), bladder
and urethra.

11. How is urea formed in
the human body?
* Urea is a product of the degradation of
amino acids. In the process amino
acids lose their amine group which is
then transformed into ammonia.
* In the ammonia reacts with carbon
dioxide to form urea and water, a
process called ureogenesis.

12. Three hormones participate in
the regulation of the renal
function :
* Antidiuretic hormone (ADH), or
vasopressin,
* Aldosterone and
* Atrial natriuretic factor (ANF).

13. HORMONES :
 Hormones are used to communicate
between organs and tissues to
regulate physiological and behavioral
activities,
 such as digestion, metabolism,
respiration, tissue function, sleep,
excretion, lactation, stress, growth and
development, movement ,
reproduction, etc.

14. * Hormones affect distant cells by
binding to specific receptor proteins in
the target cell resulting in a change in
cell function.
* The hypothalamus has special
centers for the regulation of body
fluids called osmoreceptors.

15. * The body fluid supply is low, these
centers are stimulated and sent out
impulses to the posterior lobe of the
pituitary.
* Response to this stimulus, it secretes
a hormone called antidiuretic hormone
or vasopression.

16. VASOPRESSIN:
* Vasopressin, also known as
arginine vasopressin (AVP),
antidiuretic hormone (ADH), is a
neuro hypophysial hormone found in
most mammals.
* Its two primary functions are to retain
water in the body and to constrict
blood vessels.

18. * Its transported by the blood. this
hormone is present in renal epithelium
cells of the distal tubule .
* collecting duct are highly permeable
to water .
* plays an important role in social
behavior, sexual motivation and
maternal responses to stress.

19. * It has a very short half-life between
16–24 minutes.
* It is released when the body is
dehydrated and causes the kidneys to
conserve water, thus concentrating
the urine and reducing urine volume.

21. Lack of AVP :
* Decrease or release level of AVP
leads to diabetes insipidus.
 polyuria(excess urine production)and
polydipsia (thirst).
* hypernatremia (increased
blood sodium concentration),

22. Excess AVP :
 High levels of AVP secretion may lead
to hyponatremia. (decreased
blood sodium concentration),

23. Atrial natriuretic peptide :
* It is otherwise known as atrial
natriuretic factor (ANF), atrial
natriuretic hormone (ANH),
Cardionatrine, Cardiodilatine (CDD)
or atriopeptin, is a protein
(polypeptide) hormone secreted by
heart muscle cells.
* It is involved in the homeostatic,
control of body water, sodium,
potassium and fat (adipose tissue).

25. * It is released by muscle cells in the
upper chambers (atria) of the heart
(atrial myocytes) in response to high
blood volume.
* ANP acts to reduce the water, sodium
and adipose loads on the circulatory
system, there by reducing blood
pressure.

26. Aldosterone :
* Aldosterone is a steroid hormone
(mineralo corticoid family) produced by
the outer section (zona glomerulosa)
of the adrenal cortex in the adrenal
gland.
* Na+ pumping is regulated by another
hormones called Aldosterone.

30. * The body fluid volume decrease , the
amount of Na+ in the body fluid
increases ; this leads to the
production of aldosterone.
* Aldosterone is a hormone that acts
upon the nephron tubules stimulating
the reabsorption of sodium.

31. * Aldosterone is made by the adrenal
glands , located over the superior
portion of the kidneys.