Nutrition In Human Beings

The food which animals take cannot be used directly by the cells for the metabolism of their body.

In digestion, complex food molecules are broken down both mechanically and chemically, into smaller molecules of water soluble substances that can be used by the cells. In human beings, digestion and absorption of food occurs in the alimentary canal or the digestive system

The Digestive system of Human

Humans have highly evolved and complicated digestive system consisting of an alimentary canal and different types of digestive glands.

The various organs beginning from mouth are as follows:

Mouth →Oesophagus → Stomach →Small intestine →Large intestine

Alimentary canal begins with mouth and ends with anus.

Alimentary canal consists of following organs:

Mouth

The mouth is bordered by upper and lower lips which help in taking the food into the buccal (mouth) cavity. The lips are sensitive to touch, heat and cold. They also help in speaking. The mouth leads to buccal cavity where three pairs of salivary glands are present, and on the floor of the cavity a tongue bearing taste buds is present.

Teeth

The teeth are hard structures present in the mouth cavity and are specially developed for efficient mastication, i.e., mechanically breaking the ingested food into smaller pieces.

Jaws present in buccal cavity are provided with four different types of teeth:

(i) Incisors : For cutting

(ii) Canines : For tearing

(iii) Premolars: For grinding

(iv) Molars : For grinding