Search results
Results from the WOW.Com Content Network
In vertebrates, the circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the body. [1] [2] It includes the cardiovascular system, or vascular system, that consists of the heart and blood vessels (from Greek kardia meaning heart, and Latin vascula meaning vessels).
The heart is the driver of the circulatory system, pumping blood through rhythmic contraction and relaxation. The rate of blood flow out of the heart (often expressed in L/min) is known as the cardiac output (CO). Blood being pumped out of the heart first enters the aorta, the largest artery of the body.
This part of coronary circulatory regulation is known as auto regulation and it occurs over a plateau, reflecting the constant blood flow at varying CPP & resistance. The slope of a CBF (coronary blood flow) vs. CPP graph gives 1/Resistance. Autoregulation maintains a normal blood flow within the pressure range of 70–110 mm Hg.
When blood vessels dilate, the flow of blood is increased due to a decrease in vascular resistance and increase in cardiac output [further explanation needed]. Vascular resistance is the amount of force circulating blood must overcome in order to allow perfusion of body tissues. Narrow vessels create more vascular resistance, while dilated ...
The programmed delay at the AV node also provides time for blood volume to flow through the atria and fill the ventricular chambers—just before the return of the systole (contractions), ejecting the new blood volume and completing the cardiac cycle. [8] (See Wiggers diagram: "Ventricular volume" tracing (red), at "Systole" panel.)
The narrowing of blood vessels leads to an increase in peripheral resistance, thereby elevating blood pressure. While vasoconstriction is a normal and essential regulatory mechanism for maintaining blood pressure and redistributing blood flow during various physiological processes, its dysregulation can contribute to pathological conditions.
The circulatory system uses the channel of blood vessels to deliver blood to all parts of the body. This is a result of the left and right sides of the heart working together to allow blood to flow continuously to the lungs and other parts of the body. Oxygen-poor blood enters the right side of the heart through two large veins.
The rest comes from the partially deoxygenated blood from the portal vein. The liver consumes about 20% of the total body oxygen when at rest. That is why the total liver blood flow is quite high, at about 1 litre a minute and up to two litres a minute. That is on average one fourth of the average cardiac output at rest.