Osmoregulation is the process of maintaining salt and water balance (osmotic balance) across membranes within the body. The fluids inside and surrounding cells are composed of water, electrolytes, and nonelectrolytes. An electrolyte is a compound that dissociates into ions when dissolved in water.

1. REXLIN THERES S
20-PZO-006

2. SYNOPSIS
 INTRODUCTION
 IMPORTANT TERMS-OSMOSIS, ISOTONIC,HYPOTONIC AND HYPERTONIC
 OSMOREGULATION IN FISHES
A. OSMOREGULATION IN FRESH WATER FISHES
B. OSMOREGULATION IN MARINE WATER FISHES
C. OSMOREGULATION IN MIGRATORY FISHES
 OSMOREGULATION IN BIRDS
A. OSMOREGULATION IN MARINE BIRDS
B. OSMOREGULATION IN TERRESTRIAL BIRDS
 CONCLUSION
 VIDEO
 REFERENCE
 QUESTION BANK

3.  The maintenance of an optimal concentration
of water and salts in the tissue and body
fluids of animals is called osmoregulation.
 The term was first coined by Hober (1902).
INTRODUCTION

4. OSMOSIS
Osmosis is the movement water
molecules through a selectively
permeable membrane from a region
of high water potential (region of
lower solute concentration) to a
region of low water potential (region
of higher solute concentration),

5. ISOTONIC,HYPOTONIC AND HYPERTONIC
Hypotonic animal–has a lower
concentration salt than external
environment
Isotonic animal –has a similar
concentration salt to the environment
Hypertonic animal –has a higher
concentration of salt compare to external
environment

6. TYPES OF OSMOREGULATION
 Osmoconformers
 Osmoregulators.
Osmoconformers are organisms that keep their internal fluids isotonic to their
environment, that is, they maintain an internal salinity similar to their external environment
Osmoregulators regulate the salt concentration by spending a high amount of energy .
Organisms that maintain an internal osmolarity different from the medium in which they
are immersed have been termed osmoregulators.

7. OSMOREGULATION IN FISHES
 In all fishes kidney is the main osmoregulatory organ.
 Gill membrane also helps in osmoregulation.
OSMOREGULATION IN FRESH WATER FISHES
 These fishes are Hypertonic to the environment i.e. the salt concentration of body fluid
is higher than environment
PROBLEMS
 Water continuously diffuses into fish body fluid through skin and gill membrane(Endo
osmosis)
 Ions (Na+&Cl-) diffuses out through skin and gill membranes

8. PHYSIOLOGICLADAPTATION IN
FRESHWATER FISHES
 Kidneys are adapted to excrete large
amount of dilute urine –have large
glomeruli
 These fishes do not drink water
 Active uptake of salts with the help of
chloride secreting cells present in gill
lamellae
EXAMPLE: Fresh water Teleost

9. OSMOREGULATION IN MARINE WATER
FISHES
These fishes are Hypotonic to the environment i.e.
their body fluid have less salt concentration in
comparison to surrounding water
PROBLEMS
 Water continuously diffuses out of fish body fluid
through skin and gill membrane(Exo osmosis)
 Salt diffuses from surrounding sea water into fish
body through skin and gill membrane

10. ADAPTATION INVOLVED IN MARINE BONYFISHES –EXAMPLE: Teleost
 Production of less quantity of concentrated urine because kidney has small or no glomeruli
 Drink large quantity of sea water(salt)
 Excretion of excess of salts with the help of chloride secreting cells present in gill lamellae
ADAPTATION IN MARINE CARTILAGINOUS FISHES- EXAMPLE: Sharks and Rays
 These fishes have same amount of salt in their body fluid as marine bony fishes .
 But these fishes have the ability to accumulate large amount of urea .Their tissue are adapted to
function at high concentration of urea.
 High concentration of urea makes the body fluids isotonic to seawater.
 Excess salt is excreted by rectal salt gland

11. SUMMARY

12. OSMOREGULATION IN MIGRATORY FISHES
 Catadromous fishes migrate from freshwater to seawater for spawning
Example: eel(Anguilla bengalensis)
 Anadromous fishes migrate from seawater to freshwater for spawning
Example: Salmon
 Such fishes have to regulate their blood tonicity in the two contrasting
media.
Therefore it maintains itself by
i. Drinking water or not drinking water
ii. chloride secreting cells of the gills function both as secreting and
absorbing unit

13. OSMOREGULATION IN MARINE BIRDS
 Marine birds exhibit high rate of evaporation as they are not fully submerged in water
 Many drink sea water to compensate the water loss
 Birds that can adapt to a marine habitat, the need to
excrete sodium chloride and generate free water far exceeds the
capabilities of their kidneys.
 This requirement is met by secretion of a highly concentrated
sodium chloride solution by paired supraorbital nasal salt glands
connect with the nasal cavity

14.  In birds that are fed a diet high in salt
concentration, the glands increase in size and
become even larger than normal.
 The salt gland generally remains inactive and
starts secreting only in response to an osmotic
stress
 The secreted fluid has a simple composition; it
contains mostly sodium and chloride in rather
concentration.
 EXAMPLES: Sea gulls, Cormorants, and
Pelicans
Location of salt gland in marine birds.

15. Skull of seabird has a pair of salt glands located over
the eyes that excrete salty fluid from the nostrils which
runs down grooves in the bill.

16. OSMOREGULATION IN TERRESTRIAL BIRDS
 The terrestrial habitat lacks both water and salts in the surrounding
medium ,therefore, the terrestrial animals often face the problem of both
water and salt losses.
 Water loss may be due to evaporation of water from the general body
surface
 Salt loss may be due to excretion of concentrated urine

17. PHYSIOLOGICAL ADAPTATION IN TERRESTRIAL BIRDS
 For water conservation the body is covered by means of a water proof
covering(FEATHERS) which prevents the evaporation of water from the body.
 Birds excrete a semisolid urine containing uric acid , thus minimizing water loss.
 Uric acid is quite insoluble in water, and it can be excreted without, the use of much
water.
 Within the cloaca most of the water is reabsorbed and the waste is excreted in
semisolid form.

18. HORMONAL CONTROL OF
OSMOREGULATION
VASSOPRESSINS-In birds , the hormone increases the permeability
of the renal tubules to water and thus permits more water reabsorption
and reduced urine production.
PROLACTIN-In bony fishes prolactin from anterior pituitary
enhances production of a dilute urine.

19. CONCLUSION
 Osmoregulation is an important process in animals as it allows organisms to
maintain a balance between water and minerals at the cellular level despite
changes in the external environment.
 Damage to the kidney through bacterial infection or other means is often
deadly as these organs play an important role in mechanism of
osmoregulation.

20. OSMOREGULATION IN FISHES

21. REFERENCES
1.http://epgp.inflibnet.ac.in/OsmoregulationinmarineairbreathinganimalsQuad1.pdf
2.https://www.shareyouressays.com/knowledge/short-notes-on-the-osmoregulation-in-
terrestrial-animals/115194
3.https://www.petmd.com/fish/care/Osmoregulationdiffusion.
4.https://www.frontiersin.org/articles/10.3389/fphys.2010.00013/full
BOOKS
1.Dr.P.S.Verma, B.S.Tyagi, V.K.Agarwal. Animal physiology
2.H.R.Singh,Neeraj Kumar. Animal physiology and biochemistry

22. QUESTIONS
PART-A
1.Define osmosis
2.Differentiate Hypotonic, Hypertonic, and Isotonic
3.What is osmoregulation
4.What are the organs involved in osmoregulation in fishes and birds
5.Write down the problems faced by fresh water fishes
6. Explain the physiological adaptation in fresh water fish
7. Write down the problems faced by marine water fishes
8. Explain the physiological adaptation in marine water fish
9.Give examples of fresh water fish and marine water fish

23. 10. What are Catadromous fish? Give example
11. What are Anadromous fish? Give example
12.What is the function of supraorbital nasal salt glands
13. Write down the problems faced by terrestrial birds
14. Explain the physiological adaptation in terrestrial birds
15.Why osmoregulation is an important mechanism
16.What are osmoconformer
17.What are osmoregulatory
18.Name the hormone plays an important role in osmoregulation in fishes and birds

24. PART-B
1.Explain the mechanism of osmoregulation in fishes
2. Explain the mechanism of osmoregulation in birds
PART-C
1.What is osmoregulation? Describe the physiological adaptation involved in
osmoregulation in fishes and birds.