17. Cardiovascular Integration

• two types of exercise:

  • dynamic = running, jogging, cycling
  • static = hand grip, holding heavy weight
• dynamic exercise:

  • O2 consumption increases then plateaus
  • O2 consumption is graded with level of exercise until a certain level - anaerobic threshold
  • heart rate and stroke volume increase
  • CO increases
  • vasoconstriction in GIT
  • increase in mABP
• functional hyperaemia = at local level when brain activity increases, blood flow to that region rises, supplyingactive neurones with nutrients
• exercise hyperaemia = local vasoconstriction

  • potassium, Pi, adenosine released by muscle - vasodilators
  • PGI2, NO released from endothelium - relaxation

  counteracted by mechanical influences of contraction

  • increase in bloodflow is therefore rhythmic
  • tends to decrease TPR
• subthalamic locomotor region (SLR) in hypothalamus

  • exercise integrating area
  • increases set point of baroreceptor reflex
• static exercise:

  • increase in diastolic pressure
  • mABP increases with level of contraction
  • exercise hyperaemia overcome by effects of mechanical compression caused by muscle contraction
  • exercise reflex is greater than in dynamic exercise
• alerting response:

  • activated by stress
  • increased blood flow and decreased in resistance
  • increase in respiration and increased cardiac output
  • vasoconstriction in GIT
  • vasodilation in skeletal muscle
  • baroreceptor reflex suppressed