Class 10, Science, Chapter-5, Lecture-2, Nutrition (Notes)
NUTRITION in AMOEBA:
- INGESTION
Amoeba forms pseudopodia in the direction of food particle.
When the food is completely encircled, the membrane dissolves and food vacuole is formed. - DIGESTION
Inside the food vacuole, digestive enzymes act on the food. - ABSORPTION and ASSIMILATION
The digested food diffuses into the cytoplasm and is utilised by the cell. - EGESTION
The food vacuole containing undigested food comes to the surface of amoeba and throws out the wastes.
DIGESTIVE SYSTEM in HUMAN BEING:
Digestive system in human being consists of –
- Alimentary canal
- Buccal cavity.
- Oesophagus
- Stomach
- Small intestine (Duodenum, Jejunum, Ileum)
- Large intestine (Colon, Rectum)
- Digestive Glands
- Salivary glands secrete saliva that contains Salivary amylase (Ptyalin)
- Liver and Gall bladder liver secretes Bile juice which is stored in Gall bladder
- Pancreas secretes Pancreatic juice which contains Pancreatic amylase, Trypsin, Lipase.
NUTRITION in HUMAN BEING:
- INGESTION:
Food is taken through mouth where it is chewed and pushed into the alimentary canal by the tongue. - DIGESTION:
- In the buccal cavity, saliva (containing Salivary amylase) secreted by 3 pairs of salivary glands mixes with food.
- Chewed and softened food enters oesophagus through Pharynx and moves to stomach.
- Three different types of gastric glands present in stomach secret GASTRIC JUICE (HCl + Pepsin + Mucus)
HCl makes the food acidic so that pepsin can act.
PEPSIN breaks PROTIENS into PEPTONES
Mucus protects the inner lining of the stomach from the action of the Hydrochloric acid. - Food enters duodenum where BILE from liver, PANCREATIC JUICE form Pancreas and BICARBONATE ions from duodenal wall mixes with the food.
BICARBONATES make the food ALKALINE
BILE emulsifies FAT
TRYPSIN breaks PEPTONES into PEPTIDES
AMYLASE breaks STARCH into MALTOSE
LIPASE breaks FATS into FATTY ACID and GLYCEROL - Partially digested food enter jejunum and ileum and mixes with intestinal juice which converts
PEPTIDES into AMINO ACIDS
FATS into FATTY ACID and GLYCEROL
STARCH into GLUCOSE
- ABSORBTION:
The digested food is absorbed in the ILEUM by the help of VILLI present in the inner walls of ileum.
The water is absorbed in the large intestine by the help of VILLI present in the inner walls of the large intestine. - ASSIMILATION:
The absorbed food moves with blood and is utilised for cell formation and obtaining energy. - EGESTION:
The undigested food is collected as faeces in the RECTUM and the solid waste is egested through ANUS.
Peristaltic Movement:
The rhythmic contraction of the inner lining muscles of alimentary canal to push food in forward direction is termed as peristaltic movement.
Role of Peristaltic Movement in Digestion:
Carbohydrates, Proteins and Fats are digested in different parts of alimentary canal in stages.
After being processed in one part, food must be moved to another part for further processing.
Thus, peristaltic movement helps in digestion of food