Digestion is the process in which chemical enzymes secreted from glands (liver, stomach, pancreas gall bladder) which break down the ingested food.
Digestion process starts when we put food on our tongue. If you thick about it than you can feel our tongue start releasing liquid like substance called saliva. saliva contain digestive enzyme called salivary amylase.
If you want to know in details than this post is for you sit back and read carefully.
What does our food contain:
Our food contains many substances which is widely known as nutrient. Which is also known as components of food.
So we can say that nutrients contain many components of food like fats, carbohydrates, vitamins, and minerals in the form of chemical energy.
According to the first law of energy, scientist says that energy can neither be created nor destroyed. So, we can say that we obtain energy when we eat (food) stored chemical energy. Which means food that we eat.Clausius
What does saliva contain:
Saliva contains salivary amylase, it is an enzyme which starts the digestion of starch into sugar. Saliva also contains mucus and hydrogen carbonate, saliva makes our food lubricates and hydrogen carbonate provides the ideal condition of pH (alkaline) for amylase to work. Large food particles break down into our mouth by the action of our teeth.
What happens to the chewed food:
After chewing or mastication, food goes down to our stomach through a pipe called oesophagus or food pipe, when oesophagus makes the peristaltic movement.
What does the stomach wall contain:
The stomach wall contains three tubular glands. The glands present on the wall of the stomach secrete gastric juice. The gastric juice contains three substances like hydrochloric acid (HCl), enzyme pepsin and mucus.
What about hydrochloric acid, enzyme pepsin, and mucus:
The enzyme pepsin starts the digestion of protein into simpler molecules in the acidic medium.
Hydrochloric acid makes the medium acidic. So, the enzyme pepsin can properly digest the proteins. Hydrochloric acid also helps to kill the bacteria which may enter the stomach with food. Mucus secretes from the wall of the stomach and helps to protect the inner lining of the stomach from hydrochloric acid.
Where does food go after stomach:
The digested food then goes into the small intestine by the regulation of sphincter muscles. Sphincter muscles are a types of which helps the transfer of food by moving itself. it is present in alimentary canal.
The small intestine is a long tubular structure of the alimentary canal. It is about 6.5 meters long in adult man. The Inner surface of Small intestine has a finger-like projection called villi.
The thin tubular capillaries present on the wall of villi.
Capillaries absorb the nutrients of digested food and release, the nutrients into the bloodstream. The blood carries digested food nutrients to all parts of the body. Where it becomes assimilated to the cells. The assimilated nutrients or foods further used by the body cell to obtain energy as well as for the growth and cell repair.
How stored food release energy:
Now we are going to describe how stored food release energy. The food stored in the form of glucose. During respiration, the blood receives oxygen and becomes oxygenated blood transfer the oxygen to the cells. The oxygen reacts with glucose and releases carbon dioxide, water, and energy. This process is called the Kreb’s cycle. This process enables us to work.
Melecular process of respiration:
The molecular process of respiration can be written in the form of the equation as follow:
Glucose + Oxygen = Carbon dioxide + water + Energy.
I hope it is helpful for you. For any notes request of biology, write in the comment box.
If you are interested to read about human body than read this post – Structure, Function and Cardiac cycle of The Human Heart