Peripheral resistance equation

What is meant by peripheral resistance?

Peripheral resistance is the resistance of the arteries to blood flow. As the arteries constrict, the resistance increases and as they dilate, resistance decreases. Peripheral resistance is determined by three factors: Autonomic activity: sympathetic activity constricts peripheral arteries.

What is cardiac output and peripheral resistance?

The resistance produced mainly in the arterioles is known as the systemic vascular resistance (SVR) or the peripheral vascular resistance (PVR). Cardiac output is a function of heart rate and stroke volume. If the pressure in a vessel increases then the blood flow will increase.

What is the relationship between peripheral resistance and blood pressure?

Increases in peripheral resistance, blood volume, and cardiac output result in higher blood pressure. Conversely decreases in any of these factors lead to lower blood pressure. Three main sources of peripheral resistance: Blood vessel diameter, blood viscosity, and total vessel length.

What is the difference between systemic vascular resistance and peripheral vascular resistance?

The resistance offered by the systemic circulation is known as the systemic vascular resistance (SVR) or may sometimes be called by the older term total peripheral resistance (TPR), while the resistance offered by the pulmonary circulation is known as the pulmonary vascular resistance (PVR).

Why is peripheral resistance important?

The total resistance to blood flow through peripheral vascular beds has an important influence on the cardiac output. A rise in total peripheral re sistance raises arterial blood pressure which, in turn, tends to reduce the cardiac output (1). A fall in total peripheral resistance does the reverse.

How do you reduce peripheral resistance?

The main concerns of peripheral vascular resistance are when it is at its extremes, called hypertension (too high) and hypotension (too low). Medications to lower peripheral vascular resistance include beta-blockers, diuretics, ACE-inhibitors, calcium-channel blockers, and alpha-blockers.

What are the factors that affect peripheral 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 happens to total peripheral resistance during exercise?

The decrease in total peripheral resistance is the result of decreased vascular resistance in skeletal muscle vascu- lar beds, leading to increased blood flow. The increase in blood flow to cardiac and skeletal muscle produced by exercise is called exercise hyperemia.

What is a normal SVR?

SVR is calculated by subtracting the right atrial pressure (RAP) or central venous pressure (CVP) from the mean arterial pressure (MAP), divided by the cardiac output and multiplied by 80. Normal SVR is 700 to 1,500 dynes/seconds/cm5.

What is the relationship between blood flow and resistance?

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.

Is resistance higher in veins or arteries?

Part (c) shows that blood pressure drops unevenly as blood travels from arteries to arterioles, capillaries, venules, and veins, and encounters greater resistance.

Why would an increase in total peripheral resistance increase the blood pressure?

In cardiovascular terms this is known as ‘total peripheral resistance’ (TPR). If the area available for blood to flow through is reduced then pressure will increase.

What is the most important determinant of vascular resistance?


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Term Tunica interna.Definition The layer of vascular tissue that consists of an endothelial lining and an underlying layer of connective tissue dominated by elastic fibers is the
Term Friction between the blood and the vessel wallsDefinition The most important determinant of vascular resistance is

What increases pulmonary vascular resistance?

Pulmonary vascular resistance is lowest at FRC. At low lung volumes, it increases due to the compression of larger vessels. At high lung volumes, it increases due to the compression of small vessels.

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