What is mean by combution

Burning

Combustion is the scientific word for burning.

Research has proven that ;

During combustion(burning)  a substance reacts with oxygen from the air and these  reactions happen at high temperatures, and transfer energy to the surroundings as light and heat.

This is why you see flames when things burn.

Explanation:

the endocrine system secretes hormones into blood and other body fluids. these chemicals are important for metabolism, growth, water and mineral balance, and the response to stress. hormones provide feedback to the brain to affect neural processing. reproductive hormones affect the development of the nervous system.