The blood flow of the body is dependent on the blood pressure present in the vascular system. There will less blood flow into the vessels during the high blood pressure and even in the low blood pressure. During the low blood pressure the blood flow is too slow, hence the blood is not reached to the organs in need. Same way during the high blood pressure there is constriction in the blood vessels, and hence very little amount of blood is flown in to the capillaries, and hence the organ related to that capillary will have deficient blood supply. The 120/80mm Hg is considered to be perfect blood pressure.
There are two types of the blood flow control, the short-term control and the long term control. The short-term control is basically because of baroreceptor reflex. The long-term control is due to hormonal control. In some of the situation we can switched on one of the system. If the organs normal functioning is not started, the other type can be then activated.
It works when the period of months, weeks, or days.
The need can be the result of increase or decreases in size and numbers of real blood vessels.
When there is need of seconds to minutes.
The quick change in local vasodilation and vasoconstriction.
The Regulation of the blood flow makes the organs to work on their full potential by having their own control over nutrients, oxygen and removal of the waste matter. This control is divided in to two types: the shorter duration or the short-term functions at the capillary blood regulation. It causes vasodilatation or vasoconstriction depending upon the situation present. The longer-term has a long duration time. It function when there is any increased of decreased of blood vessels of a given organ. When there are signals oxygen is got by the receptors. Then the message is sent to hypothalamus. After the hypothalamus the signals are sent to the spinal cord then to the heart and the blood vessels.