What factors increases resistance to blood flow?
The three most important factors affecting resistance are blood viscosity, vessel length and vessel diameter and are each considered below. Blood viscosity is the thickness of fluids that affects their ability to flow. Clean water, for example, is less viscous than mud.
What are the 3 factors that affect vascular resistance?
Three main sources of peripheral resistance: Blood vessel diameter, blood viscosity, and total vessel length. If arteries lose their elasticity and become more rigid, blood pressure increases.
What are the major factors affecting blood flow?
The variables affecting blood flow and blood pressure in the systemic circulation are cardiac output, compliance, blood volume, blood viscosity, and the length and diameter of the blood vessels.
How do you calculate blood flow resistance?
This is because resistance is inversely proportional to the radius of the blood vessel (one-half of the vessel’s diameter) raised to the fourth power (R = 1/r4). This means, for example, that if an artery or arteriole constricts to one-half of its original radius, the resistance to flow will increase 16 times.
What is the most important variable that determines resistance to blood flow?
There are three primary factors that determine the resistance to blood flow within a single vessel: vessel diameter (or radius), vessel length, and viscosity of the blood. Of these three factors, the most important quantitatively and physiologically is vessel diameter.
What is the relationship between resistance and flow?
Because flow and resistance are reciprocally related, an increase in resistance decreases flow at any given ΔP. Also, at any given flow along a blood vessel or across a heart valve, an increase in resistance increases the ΔP.
What are the two factors that determine blood flow?
You need to know the factors that affect blood flow through the cardiovascular system: blood pressure, blood volume, resistance, disease and exercise.
What does resistance of blood flow mean?
Resistance is a force that opposes the flow of a fluid. In blood vessels, most of the resistance is due to vessel diameter. As vessel diameter decreases, the resistance increases and blood flow decreases. Very little pressure remains by the time blood leaves the capillaries and enters the venules.
What is resistance to flow?
6 Summary and research directions. Flow resistance is what stops a river from accelerating as it flows downhill. Greater resistance implies deeper and slower flow at a given discharge, or lower velocity and discharge for a given depth. Resistance differs between reaches, and varies with discharge within a reach.
How is blood flow calculated?
Flow can be calculated by multiplying velocity, the distance moved by an object over time, with cross-sectional area. Within the circulatory system, velocity can be altered by changes in blood pressure, vessel resistance, and blood viscosity.
What are the three factors that affect the resistance of blood flow through a blood vessel and how does each factor affect resistance?
Which of the following correctly describes resistance to flow?
Which of the following correctly describes resistance to ﬂow? You correctly answered: Resistance to ﬂow increases with increased vessel length.
What are the three determinants of resistance to blood flow?
Determinants of Resistance to Flow (Poiseuille’s Equation) There are three primary factors that determine the resistance to blood flow within a single vessel: vessel diameter (or radius), vessel length, and viscosity of the blood.
What is the relationship between blood viscosity and resistance to flow?
Resistance to flow is directly proportional to blood viscosity and vessel length, and inversely related to the fourth power of the radius of the blood vessel.
What is the Poiseuille equation for blood resistance?
Summary of Resistance to blood flow. The relationship between resistance, blood vessel diameter, and blood viscosity is expressed by the Poiseuille equation (R=8nl/πr4), with resistance (R), viscosity of blood(n), length of blood vessel (l), and radius of blood vessel raised to the fourth power (r4).
When blood vessels are arranged in series The total resistance is?
When blood vessels are arranged in series, flow through each blood vessel is the same and the total resistance to blood flow (Rtotal) is equal to the sum of the resistances of each vessel: R total = R1 + R 2 + R3 + R4 . . .