DIGESTION AND ABSORPTION CLASS 12 NEET NOTES
- Carbohydrates, proteins and fats are major components of our food
- Vitamins and minerals also required in small quantities
- Food provides energy and organic materials for growth and repair of tissues
WHAT IS DIGESTION?
- Conversion of complex food substances into simple absorbable substances is called digestion.
- Animals exhibit holozoic nutrition, i.e. animals eat food which cannot be used by the cells directly; hence, food is digested first.
- Our digestive system applies both mechanical and biochemical methods for digestion
HUMAN DIGESTIVE SYSTEM
Human digestive system consists of I) Alimentary Canal II) Digestive Glands
I) ALIMENTARY CANAL
- The alimentary canal is a 6–9-metre long tube varying in diameter.
- It extends from the mouth to the anus and consists of Mouth, Oral Cavity, Pharynx, Esophagus, Stomach, Small intestine, Large intestine and Anus
- Anterior opening of the alimentary canal
- Bounded by two soft & movable lips
- Intake of food
- Leads to the buccal cavity
BUCCAL CAVITY OR ORAL CAVITY
- First cavity of the alimentary canal
- Oral cavity consists of:
- Upper part – Palate
- Lower part – Teeth & Tongue
- Vestibule is space between buccal cavity and lips
- Palate is roof of buccal cavity
- Palate has two parts i) Hard palate ii) Soft Palate
- Bony due to maxilla & palatine bones
- Has palatine Rugae
- Rugae most developed in carnivores
- Soft & Cartilage
- End of soft palate hanging structure is uvula
- Uvula help to close internal opening of Nasal chamber