Osmosis role in Animal cell describe the nature of cells in different solutions such as Hypertonic, Hypotonic and Isotonic medium cells become become Plasmolysed, Turgid and No change respectively.

1. OSMOSIS
ROLE IN ANIMALS CELLS
DEPARTMENT OF BIOTECHNOLOGY
GUIDED BY
DR.DHANANJAY SHUKLA
ASST.PROFESSOR
PRESENTED BY
DHIRENDRA KUMAR
M.Sc. I SEM

2. ABOUT OSMOSIS
• The word “osmosis” is comes from Greek word
“Osmos” means “a push” then it was make Osmosis
(during mid of 19th century).
• Osmosis is spontaneous process by which water
molecules passes through semi permeable membrane
(Cell Membrane) from lower solute concentration to
higher solute concentration until the solution comes
equilibrium.
• It was first thoroughly studied in 1877 by a German
plant physiologist Wilhelm Pfeffer and accurate study
in leaky membrane (Plasma Membrane) by in 1854 by
a British chemist, Thomas Graham.

3. TERMS USED IN OSMOSIS
Water Potential: it is a concept fundamental to understanding water movement.it is denoted as ̫Ψw.
Solute Potential: it is a magnitude of lower water potential of solution due to dissolution of solute
is called solute potential. It is denoted as Ψs.
Pressure potential: it is ability of cell wall or membrane to make swelled. It is denoted by Ψp .
According to Van’t Hoff factor that says water potential is equals to sum of solute potential and pressure
potential.
Ψw = Ψs + Ψp
where, Ψw = water potential
Ψs = solute potential
Ψp = pressure potential

4. Osmosis depends upon nature of solution as follows;
1- Hypotonic solution: if cell placed on a which has lower concentration of solute in that case cell must
be burst.
2- Isotonic solution: it is which has equal concentration of solute as well as cell’s cytoplasm
concentration.
3- Hypertonic solution : it refers a solution which has higher concentration of solute as compare to cell
in that case cell must be plasmolysed

5. Osmosis Role in Animals Cells
• It plays key role in animal cells because they will lysed when they are placed in
a hypotonic solution.
• Some cells, such as erythrocytes, will actually burst as water enters them by osmotic flow. Rupture
of the plasma membrane by a flow of water into the cytosol is termed osmotic lysis. Consequently,
it is essential that animal cells be maintained in an isotonic medium, which has a solute
concentration close to that of the cell cytosol
• Even in an isotonic environment, all animal cells face a problem in maintaining their cell volume.
Cells contain a large number of charged macromolecules and small metabolites that attract ions of
opposite charge (e.g., K+, Ca2+, PO4
3−). Also recall that there is a slow leakage of extracellular ions,
particularly Na+ and Cl−, into cells down their concentration gradient then cell must be lysed.
• To prevent this, animal cells actively export inorganic ions as rapidly as they leak in. The export of
Na+ by the ATP-powered Na+/K+ pump plays the major role in this mechanism for preventing cell
swelling. If cultured cells are treated with an inhibitor that prevents production of ATP, they swell
and eventually burst, demonstrating the importance of active transport in maintaining cell volume.

6. The Effects of Osmosis
In Plant Cells : Plant cells are enclosed by a rigid cell wall. When
the plant cell is placed in a hypotonic solution , it takes up water by
osmosis and starts to swell, but the cell wall prevents it from
bursting.this is called Turgidity but,in hypertonic solution cells must
be plasmolysed.
In Animal Cells: Animal cells do not have cell walls. In hypotonic
solutions, animal cells swell up and explode as they cannot become
turgid because absence of cell wall to prevent the cell from bursting.
In hypertonic solutions, water diffuses out of the cell due to osmosis
and the cell shrinks. Thus, the animal cell has always to be
surrounded by an isotonic solution.
In the human body, the kidneys controls regulatory system and
desaltification of salt in blood plasma which is directly controlled by
hypothalamus.

7. In Dialysis : It is a process where both the solvent molecules
and small solute molecules are able to pass through the
selectively permeable dialysis membrane but other larger
components such as large colloidal molecules like proteins
cannot pass through pores in the dialysis membranes .
The most important medical application of dialysis is in
dialysis machines, where hemodialysis is used in the
purification of blood from patients suffering from renal
malfunction. Blood from the patient is circulated through a
long cellophane dialysis tube suspended in an isotonic solution
called the dialysate which is an electrolyte solution containing
the normal constituents of blood plasma.
Reverse Osmosis: Reverse osmosis is the process by which
the liquid solvent moves across the semi-permeable membrane
against its concentration gradient,This process is also known as
hyperfiltration as it is one of the best filtration methods known
.The removal of particles as small as ions from a solution is
made possible using this method. Reverse osmosis is most
commonly used to purify water and desalination. Reverse
osmosis is capable of rejecting bacteria, salts, sugars, proteins,
particles, dyes, etc.

8. In Drug Delivery
• The osmotic-controlled release oral delivery system
(OROS) is an advanced controlled release oral drug delivery
system in the form of a rigid tablet with a semi-permeable
outer membrane and one or more small laser drilled holes in
it. As the tablet passes through the body, water is absorbed
through the semipermeable membrane via osmosis, and the
resulting osmotic pressure is used to push the active drug
through the opening in the tablet.
• OROS is a trademarked name owned by ALZA Corporation,
which pioneered the use of osmotic pumps for oral drug
delivery.

9. Why is osmosis so important?
• The most important function of osmosis is stabilising the internal environment of an organism by
keeping the water and intercellular fluids levels balanced. In all living organisms, nutrients and
minerals make their way to the cells because of osmosis. This obviously is essential to the survival
of a cell.

10. Any Query ?