Digestive System Notes

Topics: Digestion, Stomach, Small intestine Pages: 3 (680 words) Published: December 31, 2012
Digestive system

6.1.1 explain why digestion of large food molecules is essential

* Large food molecules are polymers, broken down into monomers in order to be absorbed into the blood * Humans eat substances by other organsims, many which are not suitable for human tissues therefore they must be broken down and reassembled in a form that is suitable * Many molecules in foods are too large to be absorbed by the villi in the small intestine, the large molecules have to be broken down into small molecules that can then be absorbed by diffusion, facilitated diffusion or active transport.

6.1.2 explain the need for enzymes in digestion
enzymes speed up the rate of digestion

6.1.3 state the source, substrate, product and optimum PH conditions for one amylase, one protease and one lipase

Enzyme | Main secreting glands | Optimum pH| Region where enzyme works | Amylase | Salivary glands | 7 | Mouth |
| Pancreas | 7 | Small intestine |
Protease | Stomach wall| 2| Stomach |
| Pancreas | 7 | Small intestine |
Lipase | Pancreas | 7 | Small intestine |

6.1.4 draw and label a diagram of the digestive system

6.1.5 outline the functions of the stomach, small intestine and large intestine


* the wall of the stomach is grandular, secreting mucus, hydrochloric acid and protease * hydrochloric acid creates very acid conditions that kill bacteria in food that has been swallowed. To avoid food poisoning. * Acid conditions denature proteins and suit protein digestion by hydrolysis protease secreted in the stomach ( pepsin) begins the process by breaking up polypeptides into shorter chains of amino acids * The wall of the stomach is elastic ( large meals can be swallowed quickly, stored and then gradually released in the small intestine) * The wall of the stomach is muscular and contracts rthymically to squeeze the food, mixing it and breaking it into smaller lumps Small intestine

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