EX 20 A TEST FOR BARORECEPTOR FUNCTION THE VALSALVA MANEUVER

• Baroreceptors


  Receptors located in the vascular walls, especially of the aortic arch and carotid sinus area, that are sensitive to changes in arterial blood pressure
• Chemoreceptors


  Receptors that detect changes in chemical composition of the blood or tissues
• Baroreceptors


  • They are stimulated whenever there is an increase in blood pressure
  • They cause slowing of the heart rate and increased force of ventricular contraction
  • They cause vasodilation
• The Valsalva Maneuver


  1. Take a deep breath

  2. Expire forcefully with mouth closed
• During the Valsalva Maneuver

  • Intrathoracic pressure increases
  • Peripheral arterial pressure increases
  • Venous return decreases
  • Pulse pressure decreases
• After release of the Valsalva Maneuver

  Mean arterial pressure and pulse pressure increase as blood accumulated in extra-thoracic veins floods the heart
• Baroreceptors


  • They are part of a mechanism that is important in controlling arterial blood pressure and maintaining circulation to the brain
  • They play an essential part in compensating for the effect of gravity on the circulation
• Baroreceptors and chemoreceptors are important in general
• The Valsalva Maneuver is used as a test of the efficiency of the circulation in the face of decreased venous return
• The rise in diastolic pressure and increase in heart rate that occur when the body changes position are brought about through the baroreceptor reflex