total peripheral resistance

Examples of total peripheral resistance in the following topics:

• Hypertension

  • In most people with established essential (primary) hypertension, increased resistance to blood flow (total peripheral resistance) accounts for the high pressure while cardiac output remains normal.
  • This increased peripheral resistance is mainly attributable to structural narrowing of small arteries and arterioles, although a reduction in the number or density of capillaries may also contribute.
  • Hypertension is a major risk factor for stroke, myocardial infarction (heart attacks), heart failure, aneurysms of the arteries (e.g. aortic aneurysm), peripheral arterial disease and is a cause of chronic kidney disease.

• Venous Blood Pressure

  • This value is a function of the cardiac output (total blood pumped) and total peripheral resistance (TPR).
  • TPR is primarily a function of the resistance of the systemic circulation.
  • The resistance to flow generated by veins, due to their minimal ability to contract and reduce their diameter, means that regulation of blood pressure by veins is minimal in contrast to that of muscular vessels, primarily arterioles.
  • The latter can actively contract, reduce diameter, and increase resistance and pressure.

• Congestive Heart Failure

  • This helps restore blood pressure but also increases the total peripheral resistance, increasing the workload of the heart.
  • The increased peripheral resistance and greater blood volume place further strain on the heart and accelerates the process of damage to the myocardium.

• Cardiac Output

  • It is described as MAP=CO X TPR (total peripheral resistance).
  • TPR is a measure of resistance in the blood vessels, which acts as the force by which blood must overcome to flow through the arteries determined by the diameter of the blood vessels.
  • The exact relationship is such that a twofold increase in blood vessel diameter (doubling the diameter) would decrease resistance by 16-fold, and the opposite is true as well.

• Resistance and Resistivity

  • Resistance and resistivity describe the extent to which an object or material impedes the flow of electric current.
  • What determines resistivity?
  • The potential difference (voltage) seen across the network is the sum of those voltages, thus the total resistance (the series equivalent resistance) can be found as the sum of those resistances:
  • Its resistance to the flow of current is similar to the resistance posed by a pipe to fluid flow.
  • Identify properties of the material that are described by the resistance and resistivity

• Resisitors in Series

  • The total resistance in the circuit with resistors connected in series is equal to the sum of the individual resistances.
  • The total resistance of a combination of resistors depends on both their individual values and how they are connected.
  • The total resistance in the circuit is equal to the sum of the individual resistances, since the current has to pass through each resistor in sequence through the circuit.
  • This implies that the total resistance in a series is equal to the sum of the individual resistances.
  • Calculate the total resistance in the circuit with resistors connected in series

• Introduction to Blood Flow, Pressure, and Resistance

  • Resistance to flow must be overcome to push blood through the circulatory system.
  • If resistance increases, either pressure must increase to maintain flow, or flow rate must reduce to maintain pressure.
  • Numerous factors can alter resistance, but the three most important are vessel length, vessel radius, and blood viscosity.
  • With increasing length, increasing viscosity, and decreasing radius, resistance is increased.
  • The resistance offered by peripheral circulation is known as systemic vascular resistance (SVR), while the resistance offered by the vasculature of the lungs is known as pulmonary vascular resistance (PVR).

• Resistors in Parallel

  • The total resistance in a parallel circuit is equal to the sum of the inverse of each individual resistances.
  • The total resistance of a combination of resistors depends on both their individual values and how they are connected.
  • This implies that the total resistance in a parallel circuit is equal to the sum of the inverse of each individual resistances.
  • This relationship results in a total resistance that is less than the smallest of the individual resistances.
  • Calculate the total resistance in the circuit with resistors connected in parallel

• Combination Circuits

  • In that case, wire resistance is in series with other resistances that are in parallel.
  • In the figure, the total resistance can be calculated by relating the three resistors to each other as in series or in parallel.
  • A series circuit can be used to determine the total resistance of the circuit.
  • It thus increases the total resistance and decreases the current.
  • Each is identified and reduced to an equivalent resistance, and these are further reduced until a single equivalent resistance is reached.

• Charging a Battery: EMFs in Series and Parallel

  • Usually, the cells are in series in order to produce a larger total emf .
  • But, if the cells oppose one another—such as when one is put into an appliance backwards—the total emf is less, since it is the algebraic sum of the individual emfs.
  • When two voltage sources with identical emfs are connected in parallel and also connected to a load resistance, the total emf is the same as the individual emfs.
  • But the total internal resistance is reduced, since the internal resistances are in parallel.
  • Two voltage sources with identical emfs (each labeled by script E) connected in parallel produce the same emf but have a smaller total internal resistance than the individual sources.