Autoregulatory Mechanisms

Question :

Neural, endocrine, and autoregulatory mechanisms affect blood flow, blood pressure, and eventually perfusion of blood to body tissues. Select one of the mechanisms in the previous sentence and describe in detail the effects it has on blood flow, blood pressure, and perfusion.

Answer :

Autoregulatory Mechanisms

The mechanism selected here for discussion is autoregulatory mechanisms and its effect on blood flow, blood pressure, and perfusion of blood to body tissues. Autoregulation is one of the examples of local regulation of blood flow. In the body, the organs and the tissues are capable of instrinsic regulation of blood supply at varying level to ensure that its functional and metabolic needs are met successfully. Autoregulation helps the organ in maintaining the flow of blood even if there is changes related to the perfusion pressure. As for instance, when the perfusion pressure falls towards an organ - example can be partially obstructing the organ’s arterial supply - then it leads to fall in the blood pressure of that organ. However, after few minutes it goes back to its normal levels. This kind of autoregulation takes place without the presence of hormonal or neural influences. And thus it is called as instrinsic to the particular organ. However, the responses can be modified by these influences. The decrease in the perfusson pressure at the initial stage can witness fall in the blood flow, and the reason to this can be depicted in the relation aong resistance, flow, and pressure by the formula given below:

F = (PA - PV)/R

Whenever there is a fall in the flow of blood, then dilation of resistance vessels can be witnessed and this leads to the fall in arterial resistance. Arterioles and small arteries are called as the resistance vessels. Moreover, with the fall in the resistance, flow of blood increases even if there is low perfusion pressure.

Reference

Johnson, P. C. (1986). Autoregulation of blood flow. Circulation research, 59(5), 483-495.