Human physiology contains a total of 7 chapters in NCERT textbook. The first chapter is digestion and absorption which tells us about our digestive system.
The process of conversion of complex food materials into simple forms is called digestion. Human digestive system is divided into two parts - the alimentary canal and the associated glands.
Our digestive system is complete with two openings - anterior mouth and posterior anus. The mouth leads to oral cavity also known as buccal cavity. This cavity contains teeth and tongue. There are three pairs salivary gland situated just outside the buccal cavity. These are sub maxillary gland (in on the lower jaw) parotid gland (on the cheeks) and sub lingual gland (under the tongue).
The secretions from the salivary gland comes to buccal cavity through ducts. The Saliva mainly consist of salivary amylase, some ions like sodium ion potassium ion etc. and Lysozyme enzyme.
30% of the total starch is converted into glucose in mouth by using salivary amylase. Lysozyme kills bacteria present in food. This food is now goes from buccal cavity to stomach through food pipe or oesophagus.
We have four types of teeth, so we have heterodont dentition. Majority of mammals including human beings form two set of teeth during their life. A set of temporary or milk teeth which is replaced by a set of permanent or adult teeth. This type of dentition is called diphyodont dentition.
Each tooth is embedded in a socket of jaw bone, this type of attachment is called thecodont.
Hard chewing surface of teeth is made up of enable and helps in mastication of food. Enamel is the hardest substance found in our body.
Tongue is a freely movable muscular organ. It is attached to the floor of buccal cavity by Frenulum.
Stomach is a J shaped bag having four regions - Cardiac, Fundic, Body, Pyloric. Small intestine is divided into three parts, first is duodenum then is jejunam then highly required ileum. Small intestine open to large intestine. Large intestine consists of Caecum, colon and rectum.
The wall of elementary canal has three layers. From outer to inner side these layers are Serosa muscularis, submucosa and mucosa.
Digestion starts in mouth where 30% of starch is converted to glucose by Salivary amylase.
The stomach has three types of cells these are mucus neck cells which separate mucus, peptic cell or chief cell with secrete pepsinogen, oxyntic cell or parietal cell which secrete HCL and intrinsic factor.
Pancreatic juice contains mucus, bicarbonates, trypsinogen, chymotrypsinogen, procarboxypeptidase, amylases, lipases and nucleases.
Bile contains bile pigments, bile salts, cholesterol and phospholipid, but no enzymes.
Intestinal juice is also known as succus entericus. It consist of disaccharidases, dipeptidases, lipases and nucleosidases.
No significant digestion occurs in large intestine. Most common ailment of digestive system is inflammation of the digestive tract.
Protein energy malnutrition is deficiency of protein or carbohydrate or both. It can cause marasmus and kwashiorkor.
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This Mind map contains all important notes and all concept of the chapter including digestion and it's process and absorption of the food. It is very helpful for neet and other exams during last minute revision of biology. Are you have to do is download the PDF by clicking the link given above and revise it as many times as you can.
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