in the carotid sinuses and aortic arch detect bradycardia to detect increases in blood pressure.
in the carotid sinuses and aortic arch detect bradycardia to detect increases in blood pressure.
in the carotid sinuses and aortic arch detect increases in blood pressure?
bradycardia
bullet::::- baroreceptor reflex: baroreceptors in the high pressure receptor zones detect changes in arterial pressure. these baroreceptors send signals ultimately to the medulla of the brain stem, specifically to the rostral ventrolateral medulla (rvlm). the medulla, by way of the autonomic nervous system, adjusts the mean arterial pressure by altering both the force and speed of the heart's contractions, as well as the systemic vascular resistance. the most important arterial baroreceptors are located in the left and right carotid sinuses and in the aortic arch.
blood pressure
homeostasis does not govern every activity in the body. for instance the signal (be it via neurons or hormones) from the sensor to the effector is, of necessity, highly variable in order to convey information about the direction and magnitude of the error detected by the sensor. similarly the effector's response needs to be highly adjustable to reverse the error – in fact it should be very nearly in proportion (but in the opposite direction) to the error that is threatening the internal environment. for instance, the arterial blood pressure in mammals is homeostatically controlled, and measured by stretch receptors in the walls of the aortic arch and carotid sinuses at beginnings of the internal carotid arteries. the sensors send messages via sensory nerves to the medulla oblongata of the brain indicating whether the blood pressure has fallen or risen, and by how much. the medulla oblongata then distributes messages along motor or efferent nerves belonging to the autonomic nervous system to a wide variety of effector organs, whose activity is consequently changed to reverse the error in the blood pressure. one of the effector organs is the heart whose rate is stimulated to rise (tachycardia) when the arterial blood pressure falls, or to slow down (bradycardia) when the pressure rises above set point. thus the heart rate (for which there is no sensor in the body) is not homeostatically controlled, but is one of effector responses to errors in the arterial blood pressure. another example is the rate of sweating. this is one of the effectors in the homeostatic control of body temperature, and therefore highly variable in rough proportion to the heat load that threatens to destabilize the body's core temperature, for which there is a sensor in the hypothalamus of the brain.
homeostasis