CV tut 1

• • HR increases incrementally during exercise
  • SV increases incrementally during exercise, but eventually plateaus due to venous return mechanism (smooth muscle, respiratory muscle, veins constrict)
  • CO increases incrementally during exercise
• sympathetic NS causes vasocontriction

  parasymapthetic NS causes vasodilation
• BP = CO x TPR
• • BP = CO x TPR
  • CO is what causes SBP to increase
  • TPR is what causes DBP to either stay the same or slightly decrease
• • a-vo2 = difference in o2 between veins and arteries
  • myocardium uses 65 - 70% at rest
  • H+, K+, NO and co2 released by the myocardium during exercise causes vasodilation, allowing more blood (so more o2) to reach the heart during exercise
• Submaximal levels after LT (12 week) exercise:

  • HR decrease:
  • SNS activity decrease
  • PNS activity increases
  • circulating catecholamines decrease
  • SV increases:
  • greater LV filling
  • frank starling mechanism
  • increase in LV mass
  • CO decreases
  • SBP decreases
  • DBP decreases
  • redistribution of blood:
  • flow to skeletal muscle decreases
  • flow to other tissue increases
  • a-vo2 difference increases due to peripheral changes
  • coronary blood flow increases due to improved filling time due to prolonged diastole
• parasympathetic NS releases acetylcholine, which decreases HR