Digestive System of Human Body Video Lecture | Science Olympiad Class 4

0:0:11: Our topic for today is Digestive System in Humans.
0:0:21: Digestion is a process in which complex food material is broken down into simpler substances.
0:0:29: The digestion of food in humans takes place in the alimentary canal, which is a long tube extending from the mouth to the anus.
0:0:42: The different parts of the alimentary canal are buccal cavity, food pipe or oesophagus, stomach, small intestine, large intestine and anus.
0:0:59: Two glands namely, liver and pancreas also help in digestion.
0:1:6: The food is taken in through the mouth.
0:1:9: It is chewed and mixed with saliva in the buccal cavity.
0:1:15: Saliva is a digestive juice secreted by the salivary glands.
0:1:21: The chewed food enters into the food pipe or oesophagus and is then slowly pushed into a bag like structure called stomach.
0:1:33: The food is churned in the stomach to further break it down.
0:1:38: The stomach also secretes mucous, digestive juices and hydrochloric acid.
0:1:47: The hydrochloric acid kills the bacteria in the food and makes the food acidic.
0:1:54: The food then goes into a highly coiled tube called small intestine.
0:2:1: The small intestine receives secretions from the liver and pancreas.
0:2:9: The liver secretes bile juice while the pancreas secretes pancreatic juice.
0:2:21: The walls of the small intestine also secrete juices, which help in further digestion of food.
0:2:29: The inner surface of the small intestine has finger like projections called villi.
0:2:37: The villi have extensive network of blood vessels.
0:2:43: The digested food is then passed into the blood vessels.
0:2:50: The undigested food is passed into the large intestine.
0:2:55: It is wider than the small intestine.
0:2:58: Excess of water and salts are absorbed here and undigested waste is passed out of the body through the anus.