Distribution of Cardiac output at rest and during exercise

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  • Created by: christaj
  • Created on: 08-01-16 10:09

Distribution of cardiac output at rest and during

  • At rest:
  • Cardiac out for an average adult and a trained performer is 5l/min.
  • The distribution of blood to the muscles are low.
  • It takes about 15-20% of cardiac output which is about 1l/min.
  • The distristribution of blood to the organs are high.
  • It takes about 80-85% of cardiac output which is about 4l/min.

Exercise

  • As the intensity of the exercise increases to maximan, cardiac output increases.
  • During sub-maximal exercise cardiac output for a trained athlete will increase to 15-25l/min.
  • During maximal exercise cardiac output for a trained ahtlete will increase to 20-40l/min.
  • Where as for an avergae adult, during sub-max exercises there cardiac output will increase to 10-15l/min.
  • During maximal exercise, cardiac output will increase to 20-30l/min.
  • The distribution of blood to the muscle increases and is about  80-85% of cardiac output
  • This is approximately 16-32l.
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Distribution of cardiac output at rest and during

  • Distribution of blood to the organs decreases and is about 15-20% of cardiac output
  • This is approximately 4-8l.
  • The distribution of blood to the brain remains constant which is about 700-750ml.
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Vascular shunt mechanism

  • Vascular shunt mechanism is controlled by the VCC.
  • It is located in the medulla oblongata together with the CCC and RCC.
  • Chemoreceptors:
    • detect an increase in CO2 concentrations, acidity and lactic acid.
    • detects a decrease in pH or O2
  • Baroreceptors:
    • detect an increase in blood pressure.
  • Proprioreceptors
    • detect movement of joints, muscles and tendons.
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Vascular shunt mechanism

ONLY THE BARO AND CHEMORECEPTOR can stimulate the VCC.

  • An increase in CO2 and a decrease in O2 concentration are detected by chemoreceptors.
  • It informs the VCC, which stimulates the sympathetic nerves which are located in the smooth muscular walls of the blood vessel.
  • The sympathetic nerves will cause vasocontriction of arterioles and precapillary sphincters.
  • This leads to a decrease in blood to non-essential organs.
  • Stimultaneously, there is an increase in blood to the working muscles.
  • This is because there is a decrease in sympathetic stimulation which causes the arterioles to vasodialate and the precapillary sphinters to vasodialate too.
  • This increases blood flow to the working muscles.
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