Tiêu đề 7- CLASS - COLOUR PRINT.pdf ✅

37 - 57 58 - 74 CLASS - VII BIOLOGY 1 DIGESTION AND ABSORPTION 01 - 36 2 BREATHING AND EXCHANGE OF GASES 75 - 109 3 REPRODUCTION IN ORGANISMS W.S WORK SHEETS - 1-3

INTRODUCTION : • Food is one of the basic requirements of all living organisms. • The major components of our food are carbohydrates, proteins and fats. • Vitamins and minerals are also required in small quantities. • Food provides energy and organic materials for growth and repair of tissues. The water we take in plays an important role in metabolic processes and also prevents dehydration of the body. • Biomacromolecules in food cannot be utilised by our body in their original form. They have to be broken down and converted into simple substances in the digestive system. This process of conversion of complex food substances to simple absorbable forms is called digestion and is carried out by our digestive system by mechanical and biochemical methods. General Organisation of the Human Digestive System Oral cavity Mouth Submaxillary and sublingual glands Liver Gall bladder Duodenum Transverse colon Ascending colon Ileum Caecum Vermiform appendix Parotid gland Pharynx Oesophagus Stomach Pancreas Jejunum Descending colon Anus Rectum Sigmoid colon Fats (lipids) Minerals Water Carbohydrates Proteins Vitamins Food Nutrients Major Components Required in small quantity Prevents dehydration of the body 1 01 DIGESTION AND ABSORPTION
Digestion and absorption ORIGIN OF ALIMENTARY CANAL : • The alimentary canal is tubular structure which extends from mouth to anus. • It develops from ectoderm & endoderm. ALIMENTARY CANAL : The alimentary canal begins with an anterior opening – the mouth, and it opens out posteriorly through the anus. (1) MOUTH AND BUCCOPHARYNGEAL CAVITY : • Mouth is a horizontal transverse slit like aperture which is surrounded by upper and lower lip. • The mouth leads to the buccal cavity or oral cavity. (i) Buccal vestibule • The space between the gums and cheeks where the food is stored temporarily. Human Digestive System Alimentary Canal Mouth Buccal Cavity Pharynx Oesophagus Stomach Small Intestine Large Intestine Anal Canal & Anus Digestive Glands Gastric Glands Intestinal Glands Associated Glands Salivary Glands Liver Pancreas Ectoderm - upto hard palate Endoderm - from soft palate to rectum Ectoderm - from anal canal to Anus 2