If blood loss were less than 20 percent of total blood volume, the neural regulation would usually return blood pressure to normal and redirect the remaining blood to the tissues.

However, if the patient is having excessive bleeding, the body is not getting enough blood flow. Lack of blood flow means the cells and organs do not get enough oxygen and nutrients to function properly. This causes a rapid and weak pulse, hypotension, excessive thirst, shallow breathing and unconsciousness in the patient. Many organs can be damaged as a result. This medical condition is called as shock in which patient must receive immediate treatment and can get worse very rapidly.