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.
→ 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.
→ 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.
→ Digestion is the process of conversion of complex and non-diffusible food substances into simple diffusible substances.
→ Absorption is movement of water and digested food into the wall of the alimentary canal and then into blood.
→ Digestion is accomplished by Mechanical and Biochemical processes.
→ The digestive system consists of Alimentary canal (Gut) and its associated glands.
→ Digestive glands: Salivary glands, Gastric glands, Liver, Pancreas and Intestinal glands.
→ Small Intestine is the longest part of the alimentary canal and most of the digestion takes place in small intestine.
→ The essential substances in food are carbohydrates, proteins and fats.
→ Carbohydrates provide energy, proteins are building blocks and fats provide reserve energy.
→ The tongue acts as a universal tooth brush. L.S of Tooth consists of crown, neck, root. [IPE]
→ The acidic semi digested fluid food formed in the stomach is called chyme. [IPE]
→ Liver is the largest gland in the body which secretes bile juice. [IPE]
→ Bile juice plays an important role in lipid(fat) digestion. [IPE]
→ Bile salts help in the emulsification of Fats. Bile activates lipases. [IPE]
→ In the stomach gastric acid is secreted by the parietal cells. [NEET-2016]
→ Gastric juice of infants contains pepsinogen, lipase, rennin [NEET-2015]
→ Fructose is absorbed into the blood through mucosa cells of intestine by the process called facilitated transport. [NEET-2014]
→ The enzyme composition of pancreatic juice: Lipase, Amylase, Trypsinogen, Chymotrypsinogen, Procarboxypeptidase [NEET-2017]
→ The hormones Cholecvstokiniri and secretin stimulate the production of pancreatic juice and bicarbonate. [NEET-2016]
→ The cells whose secretion protects the lining of gastro-intestinal tract from various enzymes are goblet cells. [NEET-2019]
→ Succus entericus is referred to as intestinal juice. [NEET-2021]
→ The enzyme enterokinase helps in conversion of trypsinogen into trypsin. [NEET-2020]