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Blood velocities in arteries are higher during systole than during diastole. One parameter to quantify this difference is the pulsatility index (PI), which is equal to the difference between the peak systolic velocity and the minimum diastolic velocity divided by the mean velocity during the cardiac cycle. This value decreases with distance ...
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).
When two arteries or their branches join, the area of the myocardium receives dual blood supply. These junctions are called anastomoses. If one coronary artery is obstructed by an atheroma, the second artery is still able to supply oxygenated blood to the myocardium. However, this can only occur if the atheroma progresses slowly, giving the ...
When a joint can move forward and backward, such as the neck and trunk, flexion is movement in the anterior direction. [10] When the chin is against the chest, the neck is flexed, and the trunk is flexed when a person leans forward. [10] Flexion of the shoulder or hip is movement of the arm or leg forward. [11]
Perfusion is measured as the rate at which blood is delivered to tissue, [2] or volume of blood per unit time (blood flow) per unit tissue mass. The SI unit is m 3 /(s·kg) [citation needed], although for human organs perfusion is typically reported in ml/min/g. [3] The word is derived from the French verb perfuser, meaning to "pour over or ...
The type of movement that can be produced at a synovial joint is determined by its structural type. Movement types are generally paired, with one being the opposite of the other. Body movements are always described in relation to the anatomical position of the body: upright stance, with upper limbs to the side of body and palms facing forward. [11]
Collateral circulation is the alternate circulation around a blocked artery or vein via another path, such as nearby minor vessels. [1] It may occur via preexisting vascular redundancy (analogous to engineered redundancy), as in the circle of Willis in the brain, or it may occur via new branches formed between adjacent blood vessels (neovascularization), as in the eye after a retinal embolism ...
Given the proposed manner of action of the muscle pump to increase arterial blood flow, it would seem impossible for a muscle contraction and skeletal muscle hyperemia to be uncoupled. Another experiment recently was only able to find evidence that vasodilation , not the skeletal muscle pump, was responsible for maintaining proper pressure and ...