Question

1. If systemic vascular resistance increases, what happens to blood pressure and why? There are two ways.

2. What three things determine vascular resistance? What happens to vascular resistance as each increases or decreases?

3. Of the factors above that affect resistance, which would be at play when we say that obese patients are more likely to have high blood pressure?

Answer 1

Ans :

1. Systemic vascular resistance :

It is the resistance in the circulatory system that is used to create blood pressure, the flow of blood and is also a component of cardiac function.

decrease in SVR (e.g., during exercising) will result in an increased flow to tissues and an increased venous flow back to the heart. An increased SVR will decrease flow to tissues and decrease venous flow back to the heart.

  Systemic Vascular Resistance = 80x(Mean Arterial Pressure - Mean Venous Pressure or CVP) / Cardiac Output

2. Factors

Systemic vascular resistance (SVR) refers to the resistance to blood flow offered by of the systemic vasculature, excluding the pulmonary vasculature. This is sometimes referred as total peripheral resistance (TPR). SVR is therefore determined by factors that influence vascular resistance in individual vascular beds. Mechanisms that cause vasoconstriction increase SVR, and those mechanisms that cause vasodilation decrease SVR. Although SVR is primarily determined by changes in blood vessel diameters, changes in blood viscosity also affect SVR.

The measurement of resistance or impediment of the systemic vascular bed to blood flow. An increased SVR can be caused by vasoconstrictors, hypovolemia, or late septic shock. A decreased SVR can be caused by early septic shock, vasodilators, morphine, nitrates, or hypercarbia.

Blood viscosity,

total blood vessel length,

blood vessel diameter.

Determine the resistance of the blood vessel

3 .  Systemic vascular resistance is generally not increased at such earlier stages of hypertension. 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.