Question

is thr any release of blood during the first coitus?

Answer 1

yes, if there is an intact hymen(a thin membrane in the opening of vagina) there might be small bleed during the first coitus, when the hymen(membrane) gets torn.

Answer 2

but the hymen gets torn due to many othr reasons

Answer 3

but what does an hymen do?

Answer 4

http://en.wikipedia.org/wiki/Hymen
there are other reasons for hymen to get torn other than coitus.........
Usually some sort of penetrative injury/accidents.........

There is no particular function for that small membrane in human body according to my knowledge.

Answer 5

thnxalot