Cells which are adapted to carry out a specific function in the body
A protein-digesting enzyme found in the mammalian stomach.
A group of cells in an organism that are specialised to work together to carry out a particular function.
Finger-like projections of the lining of the small intestine which increase the surface area for the absorption of digested soluble food molecules into the blood
The food you eat needs to be broken down into small soluble molecules. The whole of your digestive system works to make this happen. Enzymes speed up the breakup of molecules, and chemicals such as hydrochloric acid and bile also help.
For the digestive system to work it needs to breakdown the food as fast as possible and the soluble food molecules need to be absorbed effectively into the bloodstream so they can be carried to the cells where they are needed.
We need the energy and the chemical components of our food to be made available to the cells of our bodies quickly. The enzymes that are secreted throughout the digestive system make this possible. Without enzymes you would still be able to break down your food but it would take a very long time.
When the enzyme pepsin is in a solution at the right pH it breaks the protein in a piece of meat down into amino acids in a matter of hours.
Only a certain number of digested food molecules can diffuse into the blood over a given surface area of the intestine lining at any one time. The whole of the surface of the small intestine is covered with finger-like projections called villi which greatly increase the surface area of the small intestine. This increases the number of digested food molecules diffusing into the blood and the rate at which they diffuse.
This animation shows you the effect of folding the gut lining into 'villi' on the length of the gut. It has the same effect on the width of the gut. You can imagine how this increases the surface area available for the absorption of digested food molecules.