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Below are several examples of differing types of local blood flow regulation by specific organ type or organ system. In each case, there is a specific type of intrinsic regulation occurring in order to maintain or alter blood flow to that given organ alone, instead of creating a systemic change that would affect the entire body.
Often expressed in cm/s. This value is inversely related to the total cross-sectional area of the blood vessel and also differs per cross-section, because in normal condition the blood flow has laminar characteristics. For this reason, the blood flow velocity is the fastest in the middle of the vessel and slowest at the vessel wall.
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.
These two types of cells can be easily distinguished from one another based on the presence of the prominent round nucleus of the pericyte compared to the flat elongated nucleus of the endothelial cells. [7] Pericytes also project finger-like extensions that wrap around the capillary wall, allowing the cells to regulate capillary blood flow. [6]
Through the processes of vasoconstriction and vasodilation, these cells can actively control the rate of blood flow by means of: Contraction of cellular processes that encircle capillaries as in pericytes, which possess contractile proteins such as α-actin , tropomyosin , and myosin enabling them to contract and relax.
The entire cluster of cells is infiltrated with capillaries to provide access to the bloodstream; the high capillary density makes this one of the areas of the body with the greatest blood flow. [6] Type I cells are densely packed with vesicles containing various neurotransmitters, including dopamine, ATP, serotonin, catecholamine, released ...
A peripheral blood mononuclear cell (PBMC) is any peripheral blood cell having a round nucleus. [1] These cells consist of lymphocytes (T cells, B cells, NK cells) and monocytes, whereas erythrocytes and platelets have no nuclei, and granulocytes (neutrophils, basophils, and eosinophils) have multi-lobed nuclei. In humans, lymphocytes make up ...
To summarize, vasoconstriction is a physiological process that involves the narrowing of blood vessels, particularly arteries and arterioles, resulting in a reduction of blood flow to specific tissues or organs. This phenomenon is primarily regulated by the contraction of smooth muscle cells within the vessel walls.