AP Inter 2nd Year Zoology Notes Chapter 1(a) Digestion and Absorption

Students can go through AP Inter 2nd Year Zoology Notes Lesson 1(a) Digestion and Absorption will help students in revising the entire concepts quickly.

AP Inter 2nd Year Zoology Notes Lesson 1(a) Digestion and Absorption

→ The process of conversion of the complex food substances into their simple absorbable forms is called digestion.

→ Digestion involves both mechanical and biochemical processes.

→ Human digestive system consists of the alimentary canal and the associated glands.

→ The alimentary canal begins with the mouth and ends with the anus.

→ Mouth, oral cavity, pharynx, oesophagus, stomach, small intestine, large intestine and anus are the parts of the alimentary canal.

→ An adult human has 32 permanant teeth, which are of four different types namely incisors, canines, premolars and molars.

→ The dental formula of human adult is \(\frac{2123}{2123}\) = 32.

AP Inter 2nd Year Zoology Notes Chapter 1(a) Digestion and Absorption

→ The tongue acts as universal tooth brush and helps in mixing saliva with food, taste detection, deglution and speaking.

→ Stomach is a wide ‘J’ shaped muscular bag like structure, it has three parts cardiac portion, fundic region and pyloric region.

→ Small intestine is the longest part of the alimentary canal, it has three regions namely duodenum, jejunum and ileum.

→ Vermi form appendix is a narrow finger like projection, it is a vestigial organ arises from caecum.

→ Humans have three pairs of salivary glands namely parotid glands, the submaxillary glands and sublingual glands.

→ Salivary glands secrete saliva, contain water, salts, mucin salivary amylase and lysozyme.

→ Gastric glands are of three types namely cardiac glands, pyloricglands and fundic glands.

→ Gastric juice contains pro-enzymes like pepsinogen, pro-renin (in children).

→ Gastric juice pH ranging from 0.9 to 1.8.

→ Intestinal glands are two types namely Brunner’s glands and Crypts of lieberkuhn and secrete intestinal juice.

→ Intestinal juice contains peptidases and disaccharidases etc.

AP Inter 2nd Year Zoology Notes Chapter 1(a) Digestion and Absorption

→ Liver is the largest gland in the body, secretes bile juice.

→ Bile juice plays an important role in lipid digestion.

→ Pancreas is the second largest gland in the body; the endocrine part of pancreas secretes alkaline.panereatic juice and exocrine part secretes insulin and glucagon hormones.

→ Pancreatic juice contains trypsinogen, chymotrypisnogen, carboxy peptidase, steapsin, pancreatre amylase and nucleases.

→ Partly digested acidic food formed in the stomach is called chyme.

→ Gastrin is secreted from the epithelium of the stomach. It stimulates the secretions of HCl and pepsinogen.

→ Secretin is secreted by the epithelium of duodenum and stimulate the secretions of water and bicarbonates of the pancreatic juice.

→ Cholecystokinin is secreted from the epithelium of the duodenum and stimulate the secretion of pancreatic enzymes and the release of bile.

→ Villi and kinin secreted from intestinal villi stimulate the movement of villi to increase absorption.