Changes

==Diffusion as a Transport Mechanism==

==Diffusion as a Transport Mechanism==

Diffusion is very efficient over short distances and does not require energy.  As such it is used in a variety of body systems where gradients and membranes suited to allow it are found.  However over large distances diffusion is very slow hence the need for a circulatory system to carry say oxygen around the body.  Although oxygen enters the blood in the lungs and leaves the blood in the tissue by diffusion the circulatory system is needed to fill the gap in between.

Diffusion is very efficient over short distances and does not require energy.  As such it is used in a variety of body systems where gradients and membranes suited to it are found.  However over large distances diffusion is very slow hence the need for a circulatory system to carry say oxygen around the body.  Although oxygen enters the blood in the lungs and leaves the blood in the tissue by diffusion the circulatory system is needed to fill the gap in between.

==Diffusion Through the Lipid Bilayer==

==Diffusion Through the Lipid Bilayer==