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The major determinant of vascular resistance is small arteriolar (known as resistance arterioles) tone. These vessels are from 450 μm down to 100 μm in diameter (as a comparison, the diameter of a capillary is about 5 to 10 μm). Another determinant of vascular resistance is the pre-capillary arterioles. These arterioles are less than 100 μm ...
Note that, for cardiac function curve, "central venous pressure" is the independent variable and "systemic flow" is the dependent variable; for vascular function curve, the opposite is true. Venous return curves showing the normal curve when the mean systemic filling pressure (Psf) is 7 mm Hg and the effect of altering the Psf to 3.5, 7, or 14 ...
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 vessels decrease vascular resistance. Vasodilation acts to increase cardiac output by decreasing afterload, −one of the four determinants of cardiac output. [4]
Vascular resistance occurs when the vessels away from the heart oppose the flow of blood. Resistance is an accumulation of three different factors: blood viscosity, blood vessel length and vessel radius. [30] Blood viscosity is the thickness of the blood and its resistance to flow as a result of the different components of the blood.
The pressure drop of the arterioles is the product of flow rate and resistance: ∆P=Q xresistance. The high resistance observed in the arterioles, which factor largely in the ∆P is a result of a smaller radius of about 30 μm. [24] The smaller the radius of a tube, the larger the resistance to fluid flow.
Blood viscosity is a measure of the resistance of blood to flow. It can also be described as the thickness and stickiness of blood. This biophysical property makes it a critical determinant of friction against the vessel walls, the rate of venous return, the work required for the heart to pump blood, and how much oxygen is transported to tissues and organs.
An arteriole is a small-diameter blood vessel in the microcirculation that extends and branches out from an artery and leads to capillaries. [1]Arterioles have muscular walls (usually only one to two layers of smooth muscle cells) and are the primary site of vascular resistance.
The vascular function curve expresses how "central venous pressure" changes as a function of "systemic flow". Note that, for cardiac function curve, "central venous pressure" is the independent variable and "systemic flow" is the dependent variable; for vascular function curve, the opposite is true.