Digestive System

• The digestive system includes:

• 1- The alimentary tract.

• 2- Certain accessory glands.

• Mouth: The mouth is divided into vestibule and mouth proper

• Lips and cheeks: The lips and cheeks are composed chiefly of muscles and fat covered with skin and lined with mucous membrane.

• Gums: Gums are dense fibrous tissues covered with mucous membrane

• Teeth: Teeth:A) Permanent teeth:

A full set of adult teeth consists of 32. 8 in each half jaw counting from before backwards are: 2 incisors, 1 canine, 2 premolars, and 3 molars.

B) Deciduous teeth (Primary or milk teeth): They are 20 in number. 5 in each half jaw, counting from

before backwards are two incisors, one canine and two molars. Eruption of deciduous teeth starts at 6 months of age and is completed at two years. Eruption of permentant teeth begins at 6 years of age and ends at 12 years. The third permanent molar erupts around 18 years (Wisdom tooth).

• Tongue: The tongue is a mobile muscular organ that bulges upwards from the floor of the mouth. It is concerned with mastication, deglutition, speech and taste. The mucous membrane of the anterior 2/3 is roughened by the presence of papillae that is responsible for taste sensation.

Salivary glands

Pharynx

It is divided into-Nasopharynx-Oropharynx-Laryngo-pharynx

ff•Oesophagus

Oesophagus

The stomach is divided into three parts: •the fundus of stomach•the body of stomach•the pyloric part, which is divided into the pyloric antrum and pyloric canal and pyloric sphincter

Stomach bed

• The small intestine is concerned with completion of digestion and absorption of the digested food. It is formed of duodenum, jejnum and ileum. It is about 7 meters long.

Small intestine

Duodenum•the superior part (first part)

•the descending part (second part)

•the inferior part (third part)

•the ascending part (fourth part)

The jejunum

• The jejunum represents the proximal two-fifths.

• The ileum makes up the distal three-fifths of the small intestine

The ileum

Large intestine• It is divided

into the cecum, appendix, ascending colon, transverse colon, descending colon, sigmoid colon, rectum and anal canal.

Differences Between the Small and Large Intestine

• Teniae coli• Haustrations• Appendices

epiploica

•Plicae circulares

•Villi

•Peyer's patches

Small intestineLarge intestineLengthIt is about 7 m longIt is about 1.5 m longCaliberSmallerLarger

MobilityFreely mobileLess freely mobileTeniae coli (3 bands of

longitudinal muscles)AbsentPresent

SacculationsAbsentPresentAppendices epiplica (fat )AbsentPresent over the free surface of

the colon except the caecum, the appendix and the rectum

The mucous membraneHas permanent folds, called plicae circulares

No plicae circulares

Villi in mucosaPresentAbsentPeyer's patches (lymphatic

aggregations)Presentabsent

Differences between the small and large intestine

Liver:

LiverLiver

The liver is the largest gland in the body concered with metabolism of the absorbed food, detoxification of chemicals and secretion of the bile salts which emerge from the liver through the right and left hepatic ducts. It lies under the right copula of the diaphragm. It is formed of 2 large lobes right and left, and 2 small lobes caudate and quadrate lobes which are present on the under surface of the liver. They are separated by (porta hepatis) the hilum of the liver, through which vessels and ducts pass

Extrahepatic biliary passages

spleen