Human digestive system includes two basic things
- Alimentary canal 2. Digestive glands
1 Alimentary canal : human alimentary canal is basically a pipe of varying diameter which is designed for the maximum absorption of food. human alimentary canal is complete that is it two different openings for the ingestion of food and excretion of waste products.
parts of alimentary canal
(i) Mouth :- it is a slit like aperture guarded by the set of lips upper lip and lower lip. food is mechanically broken here with the help of teeth. tongue is there for the tasting of food and swellowing the food. the salivary glands that secreate saliva also secrete an enzyme Amylase that break down the starch into the sugar a ver first chemical change that took place.
(ii) Oesophagus :- this is simply a muscular , pipe like organ that connects the mouth to the stomach. when the food enters into it it widens from the lower part of food(bolus) and tightens from the upper part thus making the food to move into a single direction that is only towards the stomach. hence the bouncing back of food is prohibited even if we move upside down.
(iii) Stomach :- This is a sac like muscular organ which helps in mechanical and chemical breaking of food.The muscles of stomach compress and relax the stomach in a rhythmic manner and does the mechanical churning of food. Hydrochloric acid is secreted here for making the environment acidic to activate the protein digesting enzyme Pepsin. Pepsin converts the proteins into Amino acids that can be easily digested. absorption of carbohydrates also take place here. The acidic condition of stomach kills bacteria and other microorganisms. At the ending of stomach there are sphincter muscles that control the passage of substances to the small intestine.
(iv) Small intestine :- it is the longest part of intestine . The food enters from the stomach is acidic , to neutralise it bile juice enter in small intestine from the Gall bladder through bile duct. here the Lipase enzyme help in digestion of fats by converting them in fatty acids. further the emulsification of the fats also take place here. the Trypsin enzyme is also secreted here for digestion of proteins.
proteins are converted into amino acids
carbohydrates are converted into glucose
fats into fatty acids and further fatty acids into glycerol.
The digested food is taken up by the villi. Villi are the small finger like projections that are found on the inner surface if the small intestine and it increases the surface area for the better absorption of food. the villi are richly provided with blood vessels that carry digested food to different parts of the body.
(v) Large intestine :- It is larger in terms of diameter only. it is mostly absorbs the water and minerals from the substances that come from the small intestine. and finally the waste products accumulate in the rectum part of the large intestine and is removed from the body by anus which is further controlled by anal sphincter.
2. Digestive glands :- these are the various glands that help in chemical breakdown of food.
(i) Liver:- This is the largest gland that secrets bile juice that helps in the breakdown of fat. The bile juice secreated is stored in the gall bladder from where it can be used.
(ii) Pancreas :- it is a leaf like gland situated below stomach and it secretes pancreatic juice which contains the trypsin to digest proteins and lipase to digest lipids.
(iii) Salivary Glands :- This gland is situated in the buccal cavity and it converts the starch into sugar.
so by giving it a deep reading you can easily solve various questions related to digestive system.