baroreceptor reflex

• Physiological responses when clamping the carotid artery of an anesthetized cat

  1. Initial increase in blood pressure

  2. Baroreceptor reflex activation

  3. Parasympathetic activation

  4. Vasodilation

  5. Decreased heart rate

  6. Blood pressure stabilization
• Initial increase in blood pressure

  Immediately after clamping the carotid artery, blood pressure typically increases due to the sudden reduction in blood flow to the brain. This triggers a reflex response known as the baroreceptor reflex.
• Baroreceptors


  • Specialized sensory receptors located in the walls of the carotid sinus and aortic arch
  • They detect changes in blood pressure
• Baroreceptor reflex activation


  When blood pressure rises rapidly, baroreceptors signal the brainstem to initiate compensatory responses to bring blood pressure back to normal
• Parasympathetic activation


  In response to the increased blood pressure, the parasympathetic nervous system is activated. This leads to decreased sympathetic activity and increased parasympathetic activity.
• Vasodilation


  Activation of the parasympathetic nervous system causes vasodilation, which results in the relaxation of blood vessels throughout the body. This dilation helps to reduce peripheral vascular resistance, which contributes to lowering blood pressure.
• Decreased heart rate


  The parasympathetic nervous system also slows down the heart rate (bradycardia). This reduces cardiac output, further contributing to the decrease in blood pressure.
• Blood pressure stabilization


  Through the combined effects of vasodilation and decreased heart rate, blood pressure eventually stabilizes at a lower level than before the carotid artery was clamped. This stabilization occurs as the baroreceptor reflex attempts to restore homeostasis.
• Clamping the carotid artery in an anesthetized cat triggers a complex series of physiological responses aimed at counteracting the initial increase in blood pressure, ultimately leading to a decrease in blood pressure through vasodilation and bradycardia.