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Cerebral blood flow (CBF) is the blood supply to the brain in a given period of time. [8] In an adult, CBF is typically 750 millilitres per minute or 15.8 ± 5.7% of the cardiac output . [ 9 ] This equates to an average perfusion of 50 to 54 millilitres of blood per 100 grams of brain tissue per minute.
Blood squirt (blood spurt, blood spray, blood gush, or blood jet) is a projectile expulsion of blood when an artery is ruptured. Blood pressure causes the blood to bleed out at a rapid, intermittent rate in a spray or jet , coinciding with the pulse , rather than the slower, but steady flow of venous bleeding.
For this reason, the blood flow velocity is the fastest in the middle of the vessel and slowest at the vessel wall. In most cases, the mean velocity is used. [18] There are many ways to measure blood flow velocity, like videocapillary microscoping with frame-to-frame analysis, or laser Doppler anemometry. [19]
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).
This continuous flow into the venous system dilutes the concentration of larger, lipid-insoluble molecules penetrating the brain and CSF. [9] CSF is normally free of red blood cells and at most contains fewer than 5 white blood cells per mm 3 (if the white cell count is higher than this it constitutes pleocytosis and can indicate inflammation ...
Increasing blood flow to the surface (e.g., during warm weather or strenuous exercise) causes warmer skin, resulting in faster heat loss. In contrast, when the external temperature is low, blood flow to the extremities and surface of the skin is reduced and to prevent heat loss and is circulated to the important organs of the body, preferentially.
Most tissues and organs of the body can survive clinical death for considerable periods. Blood circulation can be stopped in the entire body below the heart for at least 30 minutes, with injury to the spinal cord being a limiting factor. [4] Detached limbs may be successfully reattached after 6 hours of no blood circulation at warm temperatures.
When there is an injury to a blood vessel, the endothelial cells can release various vasoconstrictor substances, such as endothelin [23] and thromboxane, [24] to induce the constriction of the smooth muscles in the vessel wall. This helps reduce blood flow to the site of injury and limits bleeding.