Image

Name

Function

1.Incisors

2.Canines.

3.Molars

1. Cut and chop.

2.Tear the food to shreds.

 3.Chewing and grinding.

Name  

Image

Function

Remarks

Tongue

“With a bitter back and sweet centre,

sour taste on the sides linger.

The tip takes the latest trend,

in licking a salty sweet blend.

Know how the buddies in the tongue,

taste the food of old and the young.”    

 This taste map, accepted earlier, does not seem to be right.

  Sensation of taste is not only from the tongue; the nose plays an important role.

Recognizes the food, mixes with saliva.

and is pushed to pharynx as  boluses.         

Salivary glands.

Deliver saliva. Saliva softens and lubricates the food . Physical change.

Saliva contains the enzyme Ptyalin (Amylase) that can chemically react with starch.

It also has a germicide, lysozyme.

1.5 L./day.

Name

Image

Function / Properties.

Remarks

Esophagus Gullet.

A well lubricated tube.

Food is transported by the rhythmic contraction and relaxation of sphincter muscles.(circular muscles

Pushing the food is a reflex action. (in voluntary)

Chewing and gulping down are voluntary actions. (You can control them)  

Method of pushing food is peristalsis. This is involuntary.

Length= 25 to 30 cm.

Width 1.5 to 2 cm.

Epiglottis

This guards the trachea. (Windpipe)

If an attempt is made to speak while you swallow, epiglottis cannot function. 

One can get choked.

Stomach

Dilated part of the tract.

Three types of cells secrete gastric juice and mucus.

Only water, salts, alcohol and a little glucose are absorbed here.

Secretions

Pepsinogen-Reacts with HCl and forms Pepsin.

Pepsin acts on proteins.

Cardiac sphincters control the inflow while the Pyloric sphincters release the chyme in an orderly manner.

Capacity =  4 to 5 litres

Time:- Approximately 2 hrs.

This will vary according to the food and the emotional conditions of the person.

1. Duodenum

This is is the first part of the small intestine.

Length;= 25 cm.

There are 2 glands pouring their secretions into the duodenum.

1. Pancreas:-  Gives Pancreatic juice. This contains 3 enzymes and bicarbonate ions.

Rate of flow 1.5 liters /day.

2. Gall bladder:- Releases bile which has been produced in the liver.

The alkaline salts in the bile emulsifies the lipids.

Bile is a greenish coloured liquid. The colour is due to the presence of degenerating matter from haemoglobin.

Capacity = approximately 30.cm3 .

                           Rate:-1 Litre//day.

2. Jejunum

Midsection of the small intestine, connecting the duodenum to the ileum.

Length about 2.5 m.

Contains villi.

3. Ileum

Highly enlarged view of the wall.

This is mainly responsible for the absorption;

The area of absorption is increased by a thousand fold due to tiny velvety like projections called villi.

The epithelial cells in these possess microvilli.

Crypt consists of younger cells which would replace the mature ones as they are discarded after a few days.

Length about 3.5m.

Absorption is not always passive. Often they have to be pushed against diffusion gradients. This has been termed active absorption

Absorbs the water.

Some salts may also be absorbed here.

Usually there are beneficial bacteria which form vitamin B and K.

Rectum

The cellulose and vegetable fibres along with dead cells and the undigested matter form the faeces. or stool.