- 12 Downloads
Baroreceptors are mechanoreceptors that contribute to the autonomic regulation of blood pressure. Baroreceptors can be divided into the arterial baroreceptors, primarily involved in the short-term regulation of blood pressure, and the cardiopulmonary baroreceptors, which react to changes in blood volume or central venous pressure.
Arterial baroreceptors, situated in the aortic arch and carotid sinus, increase their afferent output in response to distension of the arterial wall caused by increases in blood pressure within the vessel. They are sensitive to absolute pressure and rate of change of pressure, both of which vary over the cardiac cycle. The arrival of the pulse pressure wave at the baroreceptors causes distension of the vessel wall and generates pulse synchronous afferent firing that is maximal during early systole (Eckberg and Sleight 1992).
The afferent traffic from the arterial baroreceptors provides the primary input to the baroreflex mechanism, which maintains short-term blood pressure homeostasis primarily by regulating heart rate and peripheral resistance via parasympathetic and sympathetic pathways. Increased baroreceptor activation depresses heart rate via vagal parasympathetic motor neurons and leads to dilation of blood vessels within the musculature through decreased sympathetic outflow. Conversely, decreased activation of the arterial baroreceptors leads to increased heart rate and constriction of blood vessels within the musculature (Jordan 1995).
Behavioral interactions with arterial baroreceptor activation and the baroreflex are well documented. For example, physiological arousal is associated with an inhibition of the baroreflex (Marshall 1995) and increased activation of the arterial baroreceptors has been associated with a dampening of cortical and behavioral activity (Berntson and Cacioppo 2007; Eckberg and Sleight 1992).
Cardiopulmonary baroreceptors are mechanoreceptors situated in the walls of the heart chambers and in the large blood vessels leading to the heart. Their primary role is in the regulation of blood volume such that increases in blood volume or central venous pressure result in reflex forearm vasodilation together with increased salt and water excretion (Eckberg and Sleight 1992). There is evidence that cardiopulmonary baroreceptors also have an interactive effect on central arterial baroreflex interneurons (Eckberg and Sleight 1992).
References and Further Reading
- Berntson, G. G., & Cacioppo, J. T. (2007). Integrative physiology: Homeostasis, allostasis, and the orchestration of systemic physiology. In J. T. Cacioppo, L. G. Tassinary, & G. G. Berntson (Eds.), Handbook of psychophysiology (pp. 433–451). Cambridge: Cambridge University Press.CrossRefGoogle Scholar
- Eckberg, D. L., & Sleight, P. (1992). Human baroreflexes in health and disease. Oxford: Clarendon Press.Google Scholar
- Jordan, D. (1995). Central nervous integration of cardiovascular regulation. In D. Jordan & J. M. Marshall (Eds.), Cardiovascular regulation (pp. 1–14). London: The Physiological Society.Google Scholar
- Marshall, J. M. (1995). Cardiovascular changes associated with behavioural alerting. In D. Jordan & J. M. Marshall (Eds.), Cardiovascular regulation (pp. 37–59). London: The Physiological Society.Google Scholar