Kidneys and Excretion

What are Excretion and Defecation?

When cells respire to produce energy, carbon dioxide is made as a waste product. If this carbon dioxide was allowed to build up inside the body, it would be harmful. The carbon dioxide is therefore carried to the lungs to be breathed out. When animals remove harmful waste products made inside their bodies, these waste products are said to have been excreted. It is important to remember that excretion is the removal of waste products made inside the body. The faeces, the solid indigestible part of the food we eat, are not waste chemicals and they have not been made inside the body. The removal of faeces from the body is known as defecation. 

Explanation
(What is the meaning of excretion?)
(Excretion means the removal from the body, of waste chemicals that we have produce inside the body.)

(What is meant by Defecation?)
(Defecation is the undigested food from the body.)
What is carbon dioxide?
(Carbon dioxide is excreted from the lungs.)

The Importance of Water in the Body?

It is 100% true that water is vital for our body. It is rightly said that one can live for some weeks without food, but only for a few days without water. This is not amazing that importance of water is so much - seventy percent of our body is water and more than half of it is in our body cells. The cells need water to work properly. Water is needed to carry the dissolved substances through our body, and water makes up most of our blood and digestive juices.

How Do We Lose Water?
It is a proven fact that our body is continuously losing water, and replacing the water that is lost. If we want to keep our body working in a proper way, the amount of water inside it must stay roughly the same, and so the amount of water taken into the body must be equal to the amount it loses.

How We Gain Water?
We gain water as we eat and drink and use up the food to produce energy. We lose a little water in the air we breathe out. We also lose water when we sweat, and we sweat all the time. not just when we are hot. But we lose most water when we pass urine.

What is the Function of Kidneys?
Our kidneys have the delicate task of keeping the balance between the amount of water coming in and the amount of water going out exactly right.