Food is a vital necessity for us to live and of course we all of us strive to achieve our food everyday. But why food is necessary? because we are hungry
Ya of-course and why we are hungry is because it is a bodies call to replenish or restore the reserve food inside body as it is ready to use it for supply of energy. So what we ate previously gives us energy now and what we eat now gives us energy in the next requirement of the body.
But body has a very alert mechanism to use the food resources very scarcely so as to survive in times we don’t provide it with food.
When we eat food, it releases into the blood the reserve supply of glucose in the liver to provide energy to the body. But in case we don’t have food, it releases very scarcely and hence we feel weak and lethargic.
But how food is converted to energy
It is very simple. As per biochemistry,
1. Food breaks down to glucose.
2. Glucose breaks down to smaller molecules known as acetyl-coA.
3. Acetyl-CoA breaks down in the presence of oxygen (which we breath) to produce energy molecules called ATP.
4. This ATP acts as energy and fuels all the body movements, processes and also biochemical reactions reactions.
Thus food is converted to energy in our body by breakdown of glucose from food in presence of oxygen to ATP inside the mitochondria. So mitochondria are call power houses of our body cells.
Let’s see the procedure in detail:
a) Food we eat consists of carbohydrate, proteins and fats which get digested in gut to glucose, amino-acids and fatty acids respectively.
b) Glucose is stored in liver as glycogen while amino acids help in building protein and fatty acids get stored.
c) In case of need, glycogen in liver breaks down to glucose and is released into blood.
d) This glucose in the blood is absorbed into every tissue and the cells by the help of Insulin from pancreas.
e) Inside the cell, glucose breaks down into two molecules of acetyl-CoA with intermediate release of two ATP molecules.
f) These Acetyl-coA molecules enter into mitochondria and undergo a process called KREB’s cycle.
g) Here each acetyl-coA produces 2 more molecules of ATP by breaking down to water (H2O) & carbon dioxide (CO2).
Thus for production of energy we require oxygen from lungs besides food. Oxygen is needed on immediate basis and continuously while glucose is produced even from reserve supply.
Interestingly, in case of starvation, fatty acids stored convert to acetyl-coA to produce energy and aminoacids also breakdown to produce actyl-CoA to produce energy. Hence a starving person looks lean and loses his weight as the reserve substances are consumed out to produce energy.