Digestive Sys

The human digestive system consist of an alimentary canal and many digestive glands

 ALIMENTARY

CANAL : it consist of several organs like mouth ,buccal cavity ,pharynx, anus ,stomach  MOUTH: it is a transverse slit . It is bounded by two soft ,movable lips upper and lower.  ORAL(BUCCAL)CAVITY :it is a large space bounded above by yhe pallete ,below by the throat and on the sides by jaws

PHARYNX: it is about 12 cm. long vertical canal beyond the soft palate . It has two parts (a) NASOPHARYNX. it is the upper part. (b) OROPHARYNX. it is the lower part . OESOPHAGUS. It is 25 cm. long ,narrow muscular ,straight tube ,lined by startified squamous ,containing mocous glands.

CARDIAC PART FUNDUS STOMACH :it is wide J-shaped ,distensible ,muscular ,sac placed obliquely on The left side in the upper part of the abdomen just below the diaphragm .it has 4 parts : BODY PYLORIC PART

SMALL INTESTINE :it is a narrow tube about 7 meters long in a living adult. It consists of 3 parts : (A) DUODENUM : it is C – shaped about 25 cm it recieves the bile –pancreatic duct formed by the union of bile duct and pancreatic duct. (B) JEJUNUM : it is the middle part it is about 2.4 m long . (C) ILEUM : it is the lower part of the small intestine

LARGE INTESTINE • It is shorter than the small intestine . It is about 1.5 m long .it lacks villi and microvilli . It shows 3 regions : • (a) CAECUM the caecum is small ,blind sac coming off the colon at the latter’s junction with the ileum . • (b) COLON : it is wider than the small intestine . It shows ascending colon and descending colon .

(c) RECTUM :it follows the colon it is about 15 to 20 cm. long .it has longitudial folds and large blood vessels . (d) ANUS : it lies at the base of the abdomen .it is gaurded by two anal sphincters ,internal of smooth ,involuntary muscle fibres and external of stariated ,voluntary muscle fibres .