diffusion is a process in which molecule move higher to lower concentration

1. Diffusion
Types, Factor and function
Mrs. Praveen Garg
VITS College, Satna

2. Diffusion
 Diffusion is the movement of a substance from an area of high
concentration to an area of low concentration.
 Diffusion occurs in liquids and gases because their particles
move randomly from place to place.
 Diffusion is a passive process of transport. A single substance
tends to move from an area of high concentration to an area of
low concentration until the concentration is equal across the
space.
 Diffusion is an important process for living things.

3. Example of diffusion
 The perfume of a flower that quickly permeates the still air of
a room.
 A drop of food coloring diffuses throughout the water in a
glass so that, eventually, the entire glass will be colored.
 Diffusion is very important in the body for the movement of
substances.
 Such as the movement of oxygen from the air into the blood
and carbon dioxide out of the blood into the air in the lungs,
or the movement of glucose from the blood to the cells.

4. There are two types of diffusion:
 Passive Diffusion.
 Facilitated Diffusion.
Types of diffusion

5. Passive Diffusion
 It is also known as simple diffusion.
 Passive diffusion is a process in which the movement of
molecules along their concentration gradient without the
direct involvement of any other molecules.
 It can involve either the spreading of a material through a
medium or the transport of a particle across a membrane.
 Simple diffusion is relevant in chemical reactions.
 In most biological systems, diffusion occurs across a semi-
permeable membrane made of a lipid bilayer.
 The membrane has pores and openings to allow the passage of
specific molecules.

7. Facilitated Diffusion.
 Facilitated diffusion, requires the presence of another
molecule (the facilitator) in order for diffusion to occur.
 Facilitated diffusion is necessary for the movement of large or
polar molecules across the hydrophobic lipid bilayer.
 Facilitated diffusion is necessary for the biochemical processes
of every cell since there is communication between various
subcellular organelles.
 As an example, while gases and small molecules like methane
or water can diffuse freely across a plasma membrane, larger
charged molecules like carbohydrates or nucleic acids need
the help of transmembrane proteins forming pores or
channels.

9. Factors that Affect Diffusion
Temperature:
• With increase in temperature, the kinetic energy of all particles
in the system increases. This increases the rate at
which solute and solvent molecules moves.
Area of interaction:
• If the block of dry ice is broken into multiple pieces, the area that
interacts with the atmosphere immediately increases.
• The number of molecules that only collide with other carbon
dioxide particles within dry ice decreases.
• Therefore, the rate of diffusion of the gas into air also increases.

10. Concentration Gradient:
• When the medium (or solvent) has a very low concentration of
the solute, the probability of a molecule diffusing away from
the central area is higher.
Particle size:
• The diffusion of a smaller particle will be more rapid than that
of a larger-sized molecule.
• This is related to both the mass of the molecule and its surface
area. A heavier molecule with a larger surface area will diffuse
slowly, while smaller particles will diffuse more quickly.
• For example, while oxygen gas will diffuse slightly more
quickly than carbon dioxide, both of them will move more
quickly than iodine gas.

11. Functions of Diffusion
• Diffusion in the human body is necessary for the absorption of
digested nutrients, gas exchange, the propagation of nerve
impulses, the movement of hormones and other metabolites
towards their target organ and for nearly every event in
embryonic development.

12. Thank you