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.

• 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).

• The Resistance Reaction

  • Resistance is the second stage of the general adaptation syndrome, where the body has an increased capacity to respond to the stressor.
  • The result is: increased muscular tonus, increased blood pressure due to peripheral vasoconstriction and tachycardia, and increased glucose in blood.
  • Resistance is the second stage and the increased secretion of glucocorticoids plays a major role by intensifying the systemic response.
  • Resistance reaction is the second stage of the general adaptation syndrome and is characterized by a heightened resistance to a stressor.
  • Explain how the endocrine system reacts to stress in the resistance stage

• Role of the Cardiovascular Center

  • Changes in diameter affect peripheral resistance, pressure, and flow, which in turn affect cardiac output.

• Distribution of Blood

  • Blood is circulated through blood vessels by the pumping action of the heart, pumped from the left ventricle through arteries to peripheral tissues and returning to the right atrium through veins.
  • When blood vessels constrict, the flow of blood is restricted or decreased, thus retaining body heat or increasing vascular resistance.
  • When blood vessels dilate, the flow of blood is increased due to a decrease in vascular resistance.

• Angiogenesis and Disease

  • These mutations (variations) allow the cancer cells (or sub-populations of cancer cells within a tumor) to develop drug resistance and escape therapy.
  • This mosaicity allows for substantial shedding of tumor cells into the vasculature, possibly contributing to the appearance of circulating tumor cells in the peripheral blood of patients with malignancies.
  • A large number of preclinical studies have been performed with protein-, gene- and cell-based therapies in animal models of cardiac ischemia, as well as models of peripheral artery disease.

• Regulation of Blood Cholesterol Levels

  • The shell of the LDL molecule contains just one molecule of apolipoprotein B100, which is recognized by the LDL receptor in peripheral tissues.
  • When this system is deregulated, many LDL molecules appear in the blood without receptors on the peripheral tissues.
  • Reference ranges for blood tests, showing usual, as well as optimal, levels of HDL, LDL and total cholesterol in mass and molar concentrations, is found in orange color at right, that is, among the blood constituents with the highest concentration.