Diffusion And Osmosis_3rd Sem
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SILIGURI INSTITUTE OF TECHNOLOGY
Name:-Moina Ersad Dept:-Biomedical Engineering 2nd Year,3rd Semester Guide Teacher:-Sujan K.Samanta Session:-2007-2008
Diffusion:The tendency on the part of molecules , atoms , ions etc.; of gases ,liquids and solids to get evenly distributed throughout the available space on account of their random kinetic motion is called diffusion.
Images showing diffusion:-
Some important facts regarding diffusion:
Gases diffuse more rapidly then liquids, and solids are the slowest to diffuse. When the particles of diffusing substance get evenly distributed ,a state of equilibrium is reached .It stops further movement. Diffusion of particles of one substance in independent of the diffusion of particles of other substance ,provided they do not react.This is known as independent diffusion. Diffusion pressure of the individual substance is then known as Partial pressure.
Diffusion Pressure:The pressure exerted by the tendency of the particles to diffuse from the area of its higher concentration to its lower concentration is called diffusion pressure . It is proportional to the concentration of the diffusing particles.
Facilitated Diffusion:Facilitated diffusion is the transport of substances across a membrane by a transmembrane protein molecule. The transport proteins tend to be specific for one molecule (a bit like enzymes), so substances can only cross a membrane if it contains the appropriate protein.
Factors influencing diffusion:
Density:-Rate of diffusion of a substance is inversely proportional to the square root of its relative density .This is known as the Graham’s Law.
Permeability of the medium:-Rate of diffusion decreases with the decrease in density of the medium.
Temperature:-A rise in temperature increases the rate of diffusion. Eg:sugar crystals do not dissolve easily in ice cold water while they do so easily in warm water.
Diffusion pressure gradient:-Rate of diffusion is directly proportional to the difference of diffusion pressure at the two ends of the system and
Importance:
Diffusion keeps the cell wall of the internal plant tissues moist. It is a means of spreading of ions and other substances throughout the protoplast. Transpiration or loss of water as vapour is a diffusion process. Exchange of gases (CO2 and O2) between plant interior and outside occurs through diffusion. Aroma of flowers is due to diffusion of volatile aromatic compounds to attract
Fick’s law of diffusion:In the mid-1800's, Fick introduced two differential equations that quantified the above statement for the case of transport through thin membranes.
Fick's First Law states that the flux, J, of a component of concentration, C, across a membrane of unit area, in a predefined plane, is proportional to the concentration differential across that plane (see note), and is expressed by:
Fick's Second Law states that the rate of change of concentration in a volume element of a membrane, within the diffusional field, is proportional to the rate of change of concentration gradient at that point in the field, as given by: where t=time.
Graham’s law of Diffusion:The rate at which gases diffuse is inversely proportional to the square root of their densities.
Osmosis:The movement of water from its higher chemical potential to its lower chemical potential without allowing the diffusion of solute by means of a semi permeable membrane is called osmosis. A solution which can cause an osmotic entry of water into it is said to be osmotically active solution. It posses low water potential.
Process of Osmosis:-
Types of Osmosis:
Endosmosis:-It is the osmotic entry of water into a cell organ or system.
Exosmosis:-It is the osmotic withdrawal of water from a cell, organ or a system.
The figure shows what happens when 2 fresh raw eggs with their shells removed with acid are placed into sucrose solution (hypertonic) and distilled water (hypotonic). Water enters the egg in water (endosmosis) causing it to swell
Osmotic Pressure:-
The pressure required to completely stop the entry of water, into an osmotically active solution across, a semi permeable membrane is called osmotic pressure. It is measured in atmospheres,bars or pascals.
Reverse Osmosis:It is the expulsion of pure water from a solution through a semi permeable membrane under the influence of pressure higher then the osmotic pressure of the solution. Use:-It is used in removing salts from saline water as well as extra purification of water.
Factors controlling osmosis:Osmosis is driven by two factors:3.
Concentration of dissolved solute on the two sides of the semi permeable membrane.
Difference in pressure.
Osmotic concentrations:There are three types of osmotic solutions: Hypotonic solution:-A solution having low osmotic concentration as compared to other solution.
Hypertonic solution:-A solution having high osmotic concentration as compared to other solution.
Isotonic solution:-Two solution with same concentration or pressure or potential.
Importance:
Entry of soil water into root is carried out by osmosis. Osmosis performs cell to cell movement of water. Living cells remain distended or turgid only by osmotic entry of water into them. Various cell organelles like mitochondria and chloroplast will collapse if they are not able to maintain proper osmotic concentration. Many plant movements like folding and drooping of leaves in Mimosa are brought about by osmosis.
Differences between diffusion & osmosis:Diffusion
Osmosis
It
is the movement of all It is the movement of types of substances from only solvent or water the area of higher free from the area of higher energy to lower . free energy to lower. It
can operate in any medium
It
operates only in liquid medium.
It
is applicable to all types of substances
It
It
A
does not require any semi permeable membrane. It
is applicable only to solvent part of a solution. semi permeable membrane is a must for its operation.
helps in equalizing the It does not equalize the concentration of diffusing concentration of a substances throughout solvent on the two sides the available space. of the system.
Diffusion
Osmosis
References:Books: Trueman’s Book on Elementary Biology Ross and Wilson’s Book on Human Physiology. Websites: www.espwaterproducts.com www.osmoflo.com.au www.mrothery.co.uk www.colorado.edu
Name:-Moina Ersad Dept:-Biomedical Engineering 2nd Year,3rd Semester Guide Teacher:-Sujan K.Samanta Session:-2007-2008
Diffusion:The tendency on the part of molecules , atoms , ions etc.; of gases ,liquids and solids to get evenly distributed throughout the available space on account of their random kinetic motion is called diffusion.
Images showing diffusion:-
Some important facts regarding diffusion:
Gases diffuse more rapidly then liquids, and solids are the slowest to diffuse. When the particles of diffusing substance get evenly distributed ,a state of equilibrium is reached .It stops further movement. Diffusion of particles of one substance in independent of the diffusion of particles of other substance ,provided they do not react.This is known as independent diffusion. Diffusion pressure of the individual substance is then known as Partial pressure.
Diffusion Pressure:The pressure exerted by the tendency of the particles to diffuse from the area of its higher concentration to its lower concentration is called diffusion pressure . It is proportional to the concentration of the diffusing particles.
Facilitated Diffusion:Facilitated diffusion is the transport of substances across a membrane by a transmembrane protein molecule. The transport proteins tend to be specific for one molecule (a bit like enzymes), so substances can only cross a membrane if it contains the appropriate protein.
Factors influencing diffusion:
Density:-Rate of diffusion of a substance is inversely proportional to the square root of its relative density .This is known as the Graham’s Law.
Permeability of the medium:-Rate of diffusion decreases with the decrease in density of the medium.
Temperature:-A rise in temperature increases the rate of diffusion. Eg:sugar crystals do not dissolve easily in ice cold water while they do so easily in warm water.
Diffusion pressure gradient:-Rate of diffusion is directly proportional to the difference of diffusion pressure at the two ends of the system and
Importance:
Diffusion keeps the cell wall of the internal plant tissues moist. It is a means of spreading of ions and other substances throughout the protoplast. Transpiration or loss of water as vapour is a diffusion process. Exchange of gases (CO2 and O2) between plant interior and outside occurs through diffusion. Aroma of flowers is due to diffusion of volatile aromatic compounds to attract
Fick’s law of diffusion:In the mid-1800's, Fick introduced two differential equations that quantified the above statement for the case of transport through thin membranes.
Fick's First Law states that the flux, J, of a component of concentration, C, across a membrane of unit area, in a predefined plane, is proportional to the concentration differential across that plane (see note), and is expressed by:
Fick's Second Law states that the rate of change of concentration in a volume element of a membrane, within the diffusional field, is proportional to the rate of change of concentration gradient at that point in the field, as given by: where t=time.
Graham’s law of Diffusion:The rate at which gases diffuse is inversely proportional to the square root of their densities.
Osmosis:The movement of water from its higher chemical potential to its lower chemical potential without allowing the diffusion of solute by means of a semi permeable membrane is called osmosis. A solution which can cause an osmotic entry of water into it is said to be osmotically active solution. It posses low water potential.
Process of Osmosis:-
Types of Osmosis:
Endosmosis:-It is the osmotic entry of water into a cell organ or system.
Exosmosis:-It is the osmotic withdrawal of water from a cell, organ or a system.
The figure shows what happens when 2 fresh raw eggs with their shells removed with acid are placed into sucrose solution (hypertonic) and distilled water (hypotonic). Water enters the egg in water (endosmosis) causing it to swell
Osmotic Pressure:-
The pressure required to completely stop the entry of water, into an osmotically active solution across, a semi permeable membrane is called osmotic pressure. It is measured in atmospheres,bars or pascals.
Reverse Osmosis:It is the expulsion of pure water from a solution through a semi permeable membrane under the influence of pressure higher then the osmotic pressure of the solution. Use:-It is used in removing salts from saline water as well as extra purification of water.
Factors controlling osmosis:Osmosis is driven by two factors:3.
Concentration of dissolved solute on the two sides of the semi permeable membrane.
Difference in pressure.
Osmotic concentrations:There are three types of osmotic solutions: Hypotonic solution:-A solution having low osmotic concentration as compared to other solution.
Hypertonic solution:-A solution having high osmotic concentration as compared to other solution.
Isotonic solution:-Two solution with same concentration or pressure or potential.
Importance:
Entry of soil water into root is carried out by osmosis. Osmosis performs cell to cell movement of water. Living cells remain distended or turgid only by osmotic entry of water into them. Various cell organelles like mitochondria and chloroplast will collapse if they are not able to maintain proper osmotic concentration. Many plant movements like folding and drooping of leaves in Mimosa are brought about by osmosis.
Differences between diffusion & osmosis:Diffusion
Osmosis
It
is the movement of all It is the movement of types of substances from only solvent or water the area of higher free from the area of higher energy to lower . free energy to lower. It
can operate in any medium
It
operates only in liquid medium.
It
is applicable to all types of substances
It
It
A
does not require any semi permeable membrane. It
is applicable only to solvent part of a solution. semi permeable membrane is a must for its operation.
helps in equalizing the It does not equalize the concentration of diffusing concentration of a substances throughout solvent on the two sides the available space. of the system.
Diffusion
Osmosis
References:Books: Trueman’s Book on Elementary Biology Ross and Wilson’s Book on Human Physiology. Websites: www.espwaterproducts.com www.osmoflo.com.au www.mrothery.co.uk www.colorado.edu
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