DIGESTIVE SYSTEM OF MAN. Part 1

DIGESTIVE SYSTEM IN MAN:-

The digestive system of man is consist of following parts:-

1) MOUTH:-

It is the anterior opening of the gut,which is bounded by fleshy lips. The lips not only close the mouth but also help in ingestion. The mouth opens into buccal cavity.

2) BUCCAL CAVITY :-

The human buccal cavity consist of following parts as :-

a) Tongue:-

It is an elongated muscular organ which is primarily a chemical sensory organ.

Functions:-
However, during digestion its help in rolling of food.

b) Teeth:-

The buccal cavity is a chamber surrounded by two jaws,upper jaw and lower jaw. In there jaws tooth are present which are of different types is called Heterodont . These teeth are in gums are known as Therodont. In human being thesr are two sets of teeth in entire life. The teeth which appear early age are known as Milky teeth. These teeth are replaced by bony teeth.

Different types of teeth :-

* Incisors:-
These are front teeth.
 Function:
 used for cutting and bitting.

* Canines:
Canines are side teeth.
Function:
used for stretching food.

* Premolars and Molars:
These are back teeth
Function: 
used for chewing and grinding food material. By the help of these teeth the food is properly masticated.

*Dental formula:-
(i 2/2 , c 1/1, pm 2/2 , m 3/3 ) × 2 = 32

SALIVARY GLANDS:-
In the buccal cavity there are three pairs of salivary gland.These glands are:-

*Parotid gland:-
Situated below the ear pinna on inner side  of buccal cavity.

*Sublingual gland :-
Present under the tongue .

*Submandibular gland :-
Situated below the jaws.

The secretion of salivary gland is known as Saliva.
The saliva is mixed with food material. The saliva contains:-
°Water    °Mucus    ° Salt

Function:-
The food becomes soft and lubricated. It can be easily swallowed.
These are used to kill germs.

Important enzyme:

Amylase OR Ptyalin enzyme :-

Starch + ----amylase--- > carbohydrate (bolus formed)

3) PHARYNX:-

At the end of buccal cavity small part pharynx is present which opens into oesophagus. In the pharynx there is an opening known as Glottis .It lead into respiratory tract .The glottis has valve known as Epiglottis when food passes through it . It is closed by epiglottis, so the food particles cannot enter the glottis.

4) OESOPHAGUS:-

It is a narrow tube like structure. It passed through neck and then opens into stomach.

Function:-

•No enzyme is secreted in oesophagus.

•Only mucus is present to lubricate the inner walls.

•The basic propulsive movement of G.I.T is peristalsis.
                                                                                       (continue on next part b post )