Dental Formula Of Humans

Dental Formula Of Humans with example

(A) Milk teeth - These are temporary, arise at 6 - 11 month age, 20 in number

(B) Permanent teeth - arise at 6 -12 years, 32 in number

• Three pairs of salivary glands are found in mouth which releases their secretions into the buccal cavity. They secrete salivary amylase for starch digestion. So digestion of starch starts from mouth.

Tongue

It is thick, musculo-sensory organ attached posteriorly to the floor of mouth by a soft ligamentous fold.Covered by the mucous membrane of thick stratified squamous epithelium with taste buds of 4.

Weber’s gland are present along the posterior laberal margin on either side secrete mucous. Its main function is to taste the food. It also helps in swallowing of food and mucus secretion.

PHARYNX

Behind the mouth is a chamber where food and the air channels meet. This chamber or region is called pharynx. The food channel continues as oesophagus (food pipe). The air passage continues as larynx and trachea (wind pipe). The opening of the larynx is guarded by a muscular flap called epiglottis, which prevents the entry of food into the wind pipe while swallowing.

Mouth and Pharynx

Mouth and Pharynx are lined with stratified squamous epithelium of ectodermal origin, hence represent stomodeal part. The muscle layer is of skeletal muscle type hence the movement of food here is voluntary.

OESOPHAGUS

It is a straight, collapsible and muscular tube, which passes through the neck, thorax and through the diaphragm into the stomach.

It produces a wave of muscular contraction by which food passes down into the stomach.

Stomach:

It is a `J' shaped bag present on left side of abdomen. It contains several branched and tubular glands present on the inner surface of its wall, which secret gastric juice. The opening of stomach into the intestine has a ring-like muscle, the pyloric sphincter, which acts like a valve and does not open till the food in the stomach is fully mixed and churned by muscular contractions of the stomach wall.