Table of Contents
Which of the following mechanisms is the most important in regulating coronary blood flow?
It should be noted that the local metabolic regulators of arteriolar tone are usually the most important for coronary flow regulation; these feedback systems involve oxygen demands of the local cardiac myocytes.
How is coronary circulation regulated?
Coronary blood flow is dependent upon arterial pressure, diastolic time, and small vessel resistance. The system is regulated to achieve a low flow high oxygen extraction and low myocardial Po2. This setting is sensitive to change in oxygen needs.
What regulates myocardial blood flow?
Regulation of coronary blood flow is understood to be dictated through multiple mechanisms including extravascular compressive forces (tissue pressure), coronary perfusion pressure, myogenic, local metabolic, endothelial as well as neural and hormonal influences.
What is cardiac autoregulation?
Coronary autoregulation describes the capacity of the heart to maintain steady myocardial perfusion across a range of perfusion pressures. 16,17. Through metabolic dilatation, coronary blood flow can increase three- to five-fold during exercise in a healthy heart.
How is cardiac blood flow maintained during exercise?
There is also a feed-forward alpha-adrenoceptor-mediated vasoconstriction that helps maintain blood flow to the vulnerable subendocardium when heart rate, myocardial contractility, and oxygen consumption are elevated during exercise.
What is autoregulation of blood pressure?
Autoregulation is the intrinsic capacity of resistance vessels in end organs, such as heart, kidney, and brain, to dilate and constrict in response to dynamic perfusion pressure changes, maintaining blood flow relatively constant (Figure).
What does coronary blood flow depend on?
Coronary blood flow is mainly determined by local oxygen demand. The vascular endothelium is the final common pathway controlling vasomotor tone. When anaesthetising patients with coronary artery disease, maintain coronary perfusion pressure and avoid tachycardia. pressures of 60–140 mm Hg.
How is cardiac output maintained during prolonged exercise?
After approximately 30 min of heavy exercise heart rate begins to drift upward. The increase in heart rate is proportional to the decrease in stroke volume, so cardiac output is maintained during exercise.
How blood pressure is regulated during exercise?
During exercise, cardiac output (CO) increases to provide the flow needed to serve the contracting skeletal muscles. Yet, by resetting the operating point for the arterial baroreceptors, vasodilatation is regulated to make blood pressure stable or to increase during exercise.
What is autoregulation of the heart?
What happens in autoregulation of blood flow?
Autoregulation of blood flow is the well-developed mechanism whereby cerebral resistance arteries dilate during reductions in CPP and constrict during increases in CPP. As a result, blood flow to the brain remains constant over a wide range of pressures.
How does blood flow change during exercise?
Skeletal muscle blood flow increases dramatically, while blood flow to other tissues, especially the abdominal viscera and kidneys, is reduced. During heavy exercise, the vast increase in cardiac output is directed almost exclusively to contracting skeletal and cardiac muscles.
How does the cardiac cycle change during exercise?
During exercise, your heart typically beats faster so that more blood gets out to your body. Your heart can also increase its stroke volume by pumping more forcefully or increasing the amount of blood that fills the left ventricle before it pumps.