# What factors affect vascular resistance?

The three most important factors affecting resistance are blood viscosity, vessel length and vessel diameter and are each considered below.

## What factors affect vascular resistance?

The three most important factors affecting resistance are blood viscosity, vessel length and vessel diameter and are each considered below.

What is vascular resistance increased by?

When blood vessels constrict (vasoconstriction) this leads to an increase in SVR. When blood vessels dilate (vasodilation), this leads to a decrease in SVR. If referring to resistance within the pulmonary vasculature, this is called pulmonary vascular resistance (PVR).

### What is vascular resistance determined by?

For a steady flow state, the vascular resistance is derived by dividing pressure gradient by volume flow. As the systemic venous pressure is very small when compared with the mean aortic pressure, the systemic arterial resistance can be approximated as mean aortic pressure divided by cardiac output.

What is the most important factor in determining vascular resistance?

The most important factor is the vessel radius (r), such that R α 1/r4; thus, when the radius is halved, resistance increases by a factor of 16. Another factor is viscosity, n; the energy required to overcome frictional forces necessary for fluid movement is directly related to viscosity.

## What are the three factors that affect the resistance of blood flow through a blood vessel and how does each factor affect resistance?

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.

How does resistance affect blood pressure?

In the arterial system, as resistance increases, blood pressure increases and flow decreases. In the venous system, constriction increases blood pressure as it does in arteries; the increasing pressure helps to return blood to the heart.

### Does vascular resistance increase blood pressure?

Blood pressure increases with increased cardiac output, peripheral vascular resistance, volume of blood, viscosity of blood and rigidity of vessel walls. Blood pressure decreases with decreased cardiac output, peripheral vascular resistance, volume of blood, viscosity of blood and elasticity of vessel walls.

What are the causes of vasoconstriction?

What are the most common causes of vasoconstriction?

• Prescription medicines or non-prescription medicines like decongestants. These have ingredients that cause blood vessels to narrow to provide relief.
• Some medical conditions.
• Some psychological problems, such as stress.
• Smoking.
• Being outside in the cold.

## What factors increase peripheral resistance?

Peripheral resistance is determined by three factors:

• Autonomic activity: sympathetic activity constricts peripheral arteries.
• Pharmacologic agents: vasoconstrictor drugs increase resistance while vasodilator drugs decrease it.
• Blood viscosity: increased viscosity increases resistance.

Does high blood pressure cause low vascular resistance?

As hypertension is sustained, however, vascular adaptations including remodeling, vasoconstriction, and vascular rarefaction occur, leading to increased systemic vascular resistance. In this situation, cardiac output is generally normal or slightly reduced, and circulating blood volume is normal.

### What factors can affect resistance?

There are several factors that affect the resistance of a conductor;

• material, eg copper, has lower resistance than steel.
• length – longer wires have greater resistance.
• thickness – smaller diameter wires have greater resistance.
• temperature – heating a wire increases its resistance.

What are the three factors that maintain the integrity and resistance of blood capillaries?

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.