Diffusion and Osmosis
 

Look at the video on the right. Water and many minerals dissolved in solution must enter the body through diffusion and osmosis.

Diffusion is the movement of substance

Dialysis is when

Osmosis is when

The movement of water across a semipermeable membrane is called

A perfume bottle is opened in the far corner of the room, the perfume moves across the room so that a person standing on the other side can smell it. This is an example of

 

 

 

Diffusion of water molecules across a selective permeable membrane is known as osmosis. Consider the animation on the right. It shows a membrane permeable to water separating a solution of glucose from pure water.

Water moves from an area where there is low solute concentration to an area of high solute concentration, as shown by the arrow, until both concentrations are equal. The solution with a higher concentration of solute is known as hypertonic while a solution with a low concentration of solute is known as hypotonic. When both solutions reach the same concentration they are said to be isotonic.

 

The direction of movement of water molecules is determined only by the difference in total solute concentration and not by the nature of the solutes.

Consider the image on the right. It shows two solutions separated by a semi permeable membrane. Since the total concentration of solute particles is the same on both sides of the membrane, even though different solute particles exist, no net movement of water occurs.

 

 

Isotonic is a word you sometimes associate with sports drinks. Why do manufacturers advertise their sports drinks as isotonic and what does this mean?

Consider the image on the right. It shows two solutions separated by a semipermeable membrane.

Solution A is considered to be

Solution B is considered to be

Net movement of water

 

 

Consider the image on the right. It shows two solutions separated by a semipermeable membrane.

Solution A is considered to be

Solution B is considered to be

Net movement of water

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