Question

a human body has 70%of water so why the blood is fall when we injury

Answer 1

The majority of water is locked within cells, in a similar way that blood is locked within blood vessels. There is also a lot of water sitting between our cells which provides the correct environment for those cells to carry out their function and lastly, our blood is mostly water in composition.

On a macro level, if you cut tissue then vessels will spill out their contents. Vessels are under pressure so this will also aid to force blood out. On a micro level, the same damage will cause fluid movement and cellular damage will release its enclosed fluid.

Tears are a specialised liquid produced by a series of glands around the eyes. They provide protection and lubrication, as well as a medium to display emotion.

There is a rare condition called haemolacria in which blood is present in the tears due to underlying disease.

Answer 2

Blood is in concentrated form and is mixed with water. Thats why you see it.