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Vascular resistance is the resistance that must be overcome for blood to flow through the circulatory system.The resistance offered by the systemic circulation is known as the systemic vascular resistance or may sometimes be called by another term total peripheral resistance, while the resistance caused by the pulmonary circulation is known as the pulmonary vascular resistance.
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.
In fluid dynamics, drag, sometimes referred to as fluid resistance, is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid. [1] This can exist between two fluid layers, two solid surfaces, or between a fluid and a solid surface. Drag forces tend to decrease fluid velocity relative to the solid ...
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.
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 terms elastance and compliance are of particular significance in cardiovascular physiology and respiratory physiology. In compliance, an increase in volume occurs in a vessel when the pressure in that vessel is increased. The tendency of the arteries and veins to stretch in response to pressure has a large effect on perfusion and blood ...
In the longer-term the relationship between volume and blood pressure is more complex. [83] In simple terms, systemic vascular resistance is mainly determined by the caliber of small arteries and arterioles. The resistance attributable to a blood vessel depends on its radius as described by the Hagen-Poiseuille's equation (resistance∝1/radius ...
Airway resistance can also change over time. During an asthma attack the airways constrict causing an increase in airway resistance. Airway resistance can also vary between inspiration and expiration: In emphysema there is destruction of the elastic tissue of the lungs which help hold the small airways open. Therefore, during expiration ...