In: Biology

Nutrition in Humans

There are five stages in human nutrition; Ingestion, Digestion, Absorption, Assimilation and Egestion.


Expert Solution

Alimentary Canal:

Alimentary canal in humans is a long tube of varying diameter.

It starts with the mouth and ends with the anus.

Oesophagus, stomach, small intestine and large intestine are the parts of the alimentary canal.


It is the opening of the alimentary canal and helps in ingestion of food.

The buccal cavity which is present behind the mouth is also commonly referred to as the mouth.

The buccal cavity has teeth and tongue.

The set of teeth helps in the mastication of food.

The tongue has taste buds on it and thus helps in tasting the food.

The salivary glands open also in the buccal cavity and pour saliva which initiates the process of digestion.



Teeth are the hard structures present in the buccal cavity.

They help us to cut, shear and masticate the food we eat.

Vertical section of a tooth shows four layers as enamel, dentine, cement and dental pulp.

Enamel is outermost, shiny, highly mineralized and hardest part of the human body.

Dentine makes the bulk of the tooth and contains 70% inorganic salts.

Cement is present at the lining of a tooth and bony socket.

The dental pulp is the central soft part of a tooth and contains nerve endings, blood and lymph vessels along with connective tissue.

There are four types of teeth in humans, Incisors, canines, molars and premolars, each with a specific function.

Incisors cut the food, canines tear the food while molars and premolars crush it.

The dental formula in adult humans is 2:1:2:3.


Humans are omnivores, they can eat plant-based food as well as animal-based food.

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