Intelligence

Handout of Control of ABP

Prepared by Dr Magdi El Sersi (Ph.D)

Control Mechanisms in Arterial Blood pressure

T

he mechanisms controlling the circulation involve individual and cooperative effects

among neural control mechanisms, hormonal control mechanisms, and local control

mechanisms.

Neural and hormonal mechanisms are primarily involved with the control of central blood

volume and arterial pressure. Adequate central blood volume is necessary to ensure proper

cardiac output. In addition, autoregulation of blood flow would not work without some

mechanism to maintain a relatively constant arterial blood pressure.

Neural control of the cardiovascular system involves sympathetic and parasympathetic branches

of the autonomic nervous system (ANS). Blood volume and arterial pressure are monitored by

stretch receptors in the heart and arteries. Afferent nerve traffic from these receptors is integrated

with other afferent information in the medulla oblongata, which leads to activity in sympathetic

and parasympathetic nerves that adjust heart rate, myocardial contraction, arterial resistance, and

venous tone. In this way, cardiac output and systemic vascular resistance (SVR) are adjusted

to maintain arterial pressure. Sympathetic nerve activity and, more importantly, hormones, such

as arginine vasopressin (antidiuretic hormone), angiotensin II, aldosterone, and atrial

natriuretic peptide, serve as effectors for the regulation of blood volume by regulating salt and

water balance. Neural control of cardiac output and SVR plays a larger role in the moment-bymoment regulation of arterial pressure, whereas hormones play a larger role in the long-term

regulation of arterial pressure. In some situations, factors other than blood volume and arterial

pressure regulation strongly influence cardiovascular control mechanisms. These situations

include the fight-or-flight response, diving, thermoregulation, standing, and exercise.

Autonomic Neural...