Human Digestion

Biology

Concept: Human Digestion

Humans take nutrition, by taking in food from the mouth. Teeth present in the mouth crush the food into smaller particles and mixed with saliva so as to make the food soft. Saliva , released from the salivary glands, contains salivary amylase which is an enzyme that helps digest starch.

The food then enters into the oesophagus (food pipe), through which the food moves down the elimentary canal due to muscular movement called Peristalsis.

Peristalsis

The rhythemic movement of the muscles of alimentary canal, due to which the food starts moving slowly is called Peristalsis. This occurs slowly so that majority of nutrients may be extracted from the food we eat. The reverse of this process is called Reverse Peristalsis or simply vomitting.

The video below shows the entire process of digetion. Kindly watch carefully. Follow the path of food as it moves down the alimentary canal.

Another video, that would be helpful to you.

Hope you have followed the path of food from the buccal cavity to the anus. Lets recap the events of human digestion quickly.

• food enters the buccal cavity
• food crushed by teeth into smaller units
• particles are mixed with saliva, which digests starch and converts it into glucose.
• the food, mixed with saliva, moves down the alimentary canal through peristalsis.
• in the stomach, pepsin enzyme starts the digestion of protein, facilitated by HCl.
• the food enters the small intestine which recieves gastric secretions from liver, pancrease and gall bladder.
• complete digestion of food takes place in small intestine .
• The length of the small intestine differs in various animals depending on the food they eat. Herbivores eating grass need a longer small intestine to allow the cellulose to be digested. Meat is easier to digest, hence carnivores like tigers have a shorter small intestine.
• carbohydrate - glucose, protein- amino acid, fats - fatty acid and glycerol
• these basic sub-units are absorbed by tiny finger like projections called villi and tranfered to various cells of the human body through the blood stream.
• the remaining food in the intestine is transfered to colon(large intestine) where water is absorbed
• the final waste is excreted out of the body through anus.