Cockroach,insect surviving without head

It is unbelievable to say that any living being can live without head. How to believe? as the respiratory organ lie within the head and the brain which control the functions of the body is also within the head. Is there any living being that can survive without head?

Cockroach is the only one living being which has being known as the insect which can live without head for long time It is famous for having the capacity of surviving in any difficult situation. Million years ago, due to falling of meteors all the dinosaurs were disappear but the only one living being that is cockroach was able to survive at that time also. But, how is it possible that it can survive without head?

First of all, let's talk about human that how he/she die after his/her head being cut. When the head is cut off from the body there is more flow of blood. This results the decrease in pressure of blood and brings the deficiency in circulation of oxygen. Not only this ,due to deficiency of blood in the body, man ultimately dies. If blood does not come also, due to presence of respiratory organ that is nose is within head , man dies.

But the network of blood vessels is not so complicated as that of developed living being in the body of cockroach . It has open circulatory system due to which blood pressure is low. When the head of the cockroach is cut off blood coming from it immediately freezes as a result there is no chance for the overflow of blood.

For respiration, it does not have the organ like nose as that of human. It has small holes all over the body for respiration process which is called the spiracle and it is not controlled by the brain too.

The spiracles send oxygen directly to the cells through trachea. So that it is not necessary for blood to send oxygen all over the body parts. Cockroach is cold blooded animal so it is not necessary for them to take food frequently. It can survive for 2-3 weeks without any food.
Cockroach as well as other insects have ganglia in different parts of their body due to which body can perform normal activities in absence of brain too. That's why, until it is not attacked by any predators or by the bacterias or viruses attack them cockroach can survive for few weeks without head.

Why doesn't earth fall towards sun?

According to Newton's law of Gravitation, the force of attraction exists between every two bodies. But for small bodies this force is negligible. But earth and sun are two heavenly bodies having masses 6*10^24 kg and 2*10^30 kg respectively. In such case, force of attraction have a large value.

Such large force is enough to attract the earth by the sun. In such cases, earth would have collapse into the sun. But actually, it does not happen, earth is always at the fixed distance from the sun. Now the question arises, why does not earth fall into the sun although there exists a large force of attraction between them?

We know the force which is required to move a body uniformly in a circular path and acts along the radius and is directed towards the center of the circular path is termed as centripetal force.
Also, we know earth moves round the sun in a circular path. For the bodies to remain in circular path centripetal force is required which is directed towards the center. Since, the attraction force between earth and sun is towards the center of sun. So, the necessary centripetal force is provided by the attraction force between them. On the other hand, the direction of velocity with which the earth is moving is always perpendicular to the centripetal force. So, it does not have any component along the center of the sun.

Hence, the earth does not fall towards the sun due to its attraction.