What is Digestive system for class 12th Biology Board Exam
Last Updated: Dec 20, 2025
What is Digestive system for class 12th Biology Board Exam
Digestive system
The body of a multicellular organism is incredibly complex. We all know that the cell is the basic unit of life. Cells belonging to the same mechanism and performing the same function group together to form tissues. Those tissues with similar functions then combine to create organs. Multiple organs working together form the complete organism, helping us perform different tasks efficiently. For example, the brain is specifically designed for thinking, coordination, and helping us execute particular actions. The heart pumps blood throughout the body, the lungs handle oxygen exchange, and the digestive system processes food. Each organ has a specialized role, yet they all work together in harmony. This hierarchical organization—from cells to tissues, tissues to organs, and organs to complete organisms—is what makes life possible and allows complex beings like humans to function properly.
now we are going to talk about the digestive system the system which is most required to fulfill the energy needs of multicellular organisms the digestion is a process starts from the mouth and ends at anus
alimentary canal is 9 meter long and the digestion and absorption takes place within this
it includes
1- ingestion
2- digestion
3- absorption
and excretion
1 by 1 we are going to talk about every step
first 1 is ingestion
mouth or buccal cavity helps in mixing of food with saliva the teeth helps in chewing the muscular organ tongue helps in movement of food with in mouth and makes it bolus
teeth are of 4 types canine, incisors, molar and premolar the dentist code for this is 2123 for quarter of the area and use of canine is tearing for incisors it is cutting and molar and premolars are for grinding of food.
the chewing and mucous is required for the easy passage of food in the oesophagus or food pipe.
the saliva also kills bacteria and make the food slightly alkaline. our buccal cavity secrete the salivary amylase as enzymes then from food pipe it enters in the stomach with the help of paristalitic movement required
stomach secretes 3 enzymes including HCl, pepsinogen and mucus
the HCL secreted from the stomach is required for making the whole medium acidic the ph of this mixture is 2 and it kills the bacteria and the mucous secreted from the stomach wall helps in the protection of the stomach wall from the acid then the food enters into the small intestine in small intestine the first part of it the secretion of liver that is the bile juice through the bile duct mixed with pancreatic juice through common duct then enters into the small intestine
Here in the intestine the food get mixed with the bile juice which helps in the emulsification of fat and the emulsify the fat globules and then the pancreatic juice acts on it and the food keeps on digesting to get into its smaller composition the walls of stomach have the tiny things known as villi which increases the surface area and help in the digestion of food the length of small intestine is 6.6 meter and then the food travels to the large intestine and the water absorbed from there and the remaining unable to absorb food is removed by the anus by mass peristaltic movement.
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