RBSE Class 11 Biology Notes Chapter 16 Digestion and Absorption

These comprehensive RBSE Class 11 Biology Notes Chapter 16 Digestion and Absorption will give a brief overview of all the concepts.

RBSE Class 11 Biology Chapter 16 Notes Digestion and Absorption

→ Digestion is a process in which complex components of the food are converted into simple absorbable molecules.

→ Digestion may be intracellular or extra cellular.

→ All the organelles and accessory glands related to digestion of food, collectively known as digestive system.

→ Human digestive system includes an alimentary canal and related digestive glands.

→ The alimentary canal of human being is divided into buccal cavity, pharynx, oesophagus, stomach, small intestine and large intestine.

→ There are three digestive glands associated with alimentary canal-salivary glands, liver and pancreas.

→ The process of digestion is completed in five steps:

1. Ingestion,
2. Digestion,
3. Absorption,
4. Assimilation and
5. Egestion.

 

→ The food is chewed and masticated in buccal cavity. Teeth chew the food and tongue manipulate the food and helps mixing saliva in it. Tongue also identify the taste of food.

→ The salivary amylase present in saliva starts digestion of starch in mouth and turns it into maltose.

→ Food from buccal cavity reaches into stomach as holing by peristaltic movement through oesophagus.

→ Digestion of proteins starts in the stomach, for which the required acidic medium is established by HCl secreted by the parietal cells of the stomach.

→ Partially digested food in stomach, now is called chyme, reaches in duodenum part of small intestine. Bile from liver, and pancreatic juice from pancreas are mixed here in the food. Here most of the food is digested.

→ Food from duodenum now reaches in ileum part of small intestion. Here remaining parts of the food is digested. Food is digested in alkaline medium in small intestine. Intestinal juice from intestine, mix in food in ileum.

→ As a result of digestion proteins are converted into amino acids, carbohydrates into glucose, fructose and galactose and fats are broken into fatty acids and glycerol.

→ Digested food is mainly absorbed in the small intestine. Some substances like alcohol and some salts are absorbed in stomach while some salts and water are absorbed in large intestine also. Glucose and other mono saccharides and amino acids are absorbed in the blood capillaries by diffusion and active transport through coordination with Na⁺ ions.

→ Fats are also absorbed as monoglycerides and free fatty acids in the lymph capillaries of the intestine.

→ After the absorption of digested food the undigested remains of the food reach large intestine where water and some salts are absorbed from it.

→ The undigested remains are converted into faeces in large intestine and egested out through rectum and anus.

→ Digestion: The process of intake, digestion, assimilation and egestion of food is called digestion.

→ Nutrients: The substances which release energy on oxidation. 

→ Ingestion: The process of intake of food into the mouth.

→ Absorption: Entry of different substances from external environment, body cavity or hollow visceral organs into blood or lymph through biological membrane.

→ Assimilation: The utilization of absorbed substances by cells is known as assimilation,

→ Metabolites: The assimilated substances are called metabolites.

→ Glycogenesis: Excess of glucose is converted into glycogen, it is called glycogenesis.

→ Gluconeogenesis: Whenever required, liver cells start converting amino acids and glycerol into glucose, this process is called gluconeogenesis.

→ Egestion: Removal of undigested food from body as faeces.

→ Excretion: Elimination of waste substances from the body.

→ Balance diet: The food which includes all the nutrient as required.

→ Functional energy: The energy which is provided to body from nutrients.

→ Crypts of Lieberkuhn: Tubular glands found in intestinal mucosa.

→ Vermiform appendix: A vestigial organ placed at the junction of small intestine and large intestine in human.

→ Deglutition: Ingestion of the bolus of food by oesophagus is called deglutition.

→ Chyme: Semi fluid food with pancreatic juice

→ Hunger: The intrinsic desire of food is called hunger

→ Under nutrition: No availability of proper food for long period.

→ Over nutrition: Intake of more food than required.

→ Deficiency disease: The disease caused due to deficiency of nutrients.