16, Digestion and Absorption Class 11

Digestion and Absorption Notes for Class 11 biology Download pdf Chapter 16 Digestion and Absorption Download in pdf

Chapter 16 Digestion and Absorption

Notes For Biology Class11 Download In PDF

POINTS TO REMEMBER

Digestion : The process in alimentary canal by which the complex food is converted mechanically and biochemically into simple substances suitable for absorption and assimilation. Food : A substance which on taken and digested in the body provides mate- rials for growth, repair, energy, reproduction, resistance from disease or regulation of body processes.

Thecodont : The teeth embedded in the sockets of the jaw bone. e.g., in mammals. Diphyodont : The teeth formed twice in life time e.g., in mammals.

Peristalsis : The involuntary movement of the gut by which the food bolus is pushed forward.

Degluttition : The process of swallowing of food bolus. It is partly voluntary and partly involuntary.

Ruminants : The herbivours animals (e.g., cow, buffalo etc.) which have symbiotic bacteria in the rumen of their stomach which synthesize enzymes to hydrolyse cellulose into short chains fally acids.

Diarrhoea : The abnormal frequent discharge of semisolid or fluid faecal matter from the bowel.

Vomitting : The ejection of stomach contents through the mouth, caused by antiperistalsis.

Dysentry : Frequent watery stools often with blood and mucus and with pain, fever and causes dehydration.

Chyme : The semifluid mass into which food is converted by gastric secretion and which passes from the stomach into the small intestine.

Goblet cells : The cells of intestinal mucosal epithelium which secrete mucus.

Glissons capsule : The connective tissue sheath which covers the hepatic lobules of liver.

Hepatic lobules : The structural and functional units of liver containing hepatic cells which are arranged in the form of cords.

Sphincter of Oddi : The sphincter which guard the opening of common hepato-pancreatic duct.

Villi : The small finger-like folding in the innermost layer of the alimentary canal which increase the absorption surface area.

PEM : Protein Energy Malnutrition.

Basic steps of Holozoic Nutrition : 
(1) Ingestion : Intake of food.
(2) Digestion : Breaking down of complex organic food materials into simpler, smaller soluble molecules.
(3) Absorption and assimilation : Absorption of digested food into blood or lymph and its use in the body cells for synthesis of complex components. (4) Egestion : Elimination of undigested food as faeces.

Digestive glands : (A) Salivary glands (found in mouth).

Three types are :
(i) Parotid
(ii) Sublingual
(iii) Submaxillary.

Secrete saliva which contains ptyalin (Salivary amylase)
(B) Pancreas : Secretes pancreatic juice.
(C) Liver : Secretes bile.
(D) Gastric glands : Secretes gastric juice.
(E) Intestinal glands : Secretes intestinal juice or succus entericus.