BARORECEPTORS

• Baroreceptors are stretch receptors located in the walls of the carotid sinus, near the bifurcation of the common carotid arteries. They are sensitive to stretch and can be easily activated.
• Physiology of baroreceptors:

  1. Baroreceptor Activation

  Baroreceptor activation begins with the detection of blood pressure changes. An increase or decrease in blood pressure serves as the primary trigger for baroreceptor activation.
• 2. Signal Transmission

  An increase in blood pressure causes an increased stretch of the baroreceptors. This stretch generates an afferent signal that is transmitted through nerve pathways to the brainstem. The signal is then relayed via the glossopharyngeal nerve (Cranial Nerve IX) from the carotid sinus and the vagus nerve (Cranial Nerve X) from the aortic arch.
• 3. Integration in the Medulla

  The brainstem processes the information in the medulla oblongata, specifically in the Nucleus Tractus Solitarius (NTS), which plays a key role in regulating cardiovascular function.
• 4. Efferent Response

  The Nucleus Tractus Solitarius (NTS) generates an efferent response, which regulates the autonomic nervous system to adjust heart rate, blood vessel diameter, and other factors to restore normal blood pressure.
• 5. Effect on Heart and Vessel

  • Heart rate and Contractility = decrease due to parasympathetic responses (increase blood pressure)
  • Heart rate and Contractility = Increase (decrease blood pressure = decrease stretch of baroreceptors = send signal baroreceptors to NTS however since not really stretched there will be activation of cardio accelerator center = sympathetic response)
• Chronotropy = Heart rate
• Inotropy = Contractility
• Major effect = The primary adjustment is in heart rate, but blood vessels can also be affected, leading to changes in blood pressure.