Question

Describe the interaction between central command, arterial baroreflexes, and skeletal muscle afferents during acute exercise (low intensity to high intensity exercise). Alsoo briefly describe these 3 neural components that mediate acute exercise responses

Answer 1

• Acute exercise is mediated by 3 neural components

1. exercise pressor reflex
2. central command
3. arterial baroreflex

• Arterial baroreflex
• acute exercises lead to the increase in the blood pressure whic causes the stretching of baroreceptors on the arteries, thus senting signal to the vasomotor center of the medulla with the help of buffer nerves
• this center lays a major role in the regulation of cardiac activity
• the efferent impluse will be generated from the cardio - inhibitor center , which is passed on to the vagus nerve causing reduction in the heart rate by vasodilation
• thus increase in th blood pressure is regulated
• if the blood pressure drop , again baroreceptor sent the signal to the cardio - accelerated center and vasomotor of the medulla.Signal from the medulla cause stopping of the cardio - inhibitory ction and the signal to the cardio - accelerator with the sympathetic nerves cause the vasoconstriction results in the increase blood flow so th heart rate also increase
• exercise pressor reflex
• these work by the mechanoreceptors and metaboreceptors present on the skeletal muscle.
• in humans these to reflexes can not be distinguished
• mechanoreceptors act on the basis of metabolites released during the exercise such as ATP, lactic acid etc., in the presence of oxygen
• the metabolites activate the mechanoreceptors while metaboreceptors activation by the means of muscle contraction
• the mechanoreceptor activate the feedback of  the cardiovascular control center . Thus causing the increase in the heart rate with the muscle contraction
• this can be get activatated even in the low intensity exercise
• this also regulate the cardiac output and systemic vascular resistance
• with the muscle contraction SVR will get increased due to the activation of the sympathetic vasoconstriction
• thus even the low intensity exercise cause increase in the HR, SVR, CO in the body in response to the exercise pressor reflex which evoking the mechanical receptors
• central command
• act by the feed forward mechanism with parallel activation of the motor and cardiac reflexes
• it consists of motor neurons which get activated with the exercise, this cause autonomic neurons activity which is sensed by various sites in the brain along with exercise pressor reflex
• This will cause cardiovascular regulation
• periaqueduct grey(PAG) get activated during the exercise
• Also the exercise pressor reflex cause change in the heart rate
• the central command can regulate heart rate with sympatetic and parasympathetic neurons
• Thus with exercise pressor reflex the motor center of the brain get activated and which cause increase in the pressure and heart rate
• Thus as conclusion the exercise pressor reflex in the skeletal muscle sent the reflexes through skeletal afferent to the central command mainly on the medulla, which is vasomotor center for the controlling of the pressure increase or decrease. the increase in the pressure is cause activation of the cardio - inhibitor center . A parallel action is observed with the baroreflex , the increase in the pressure sensed and sent signal to the medulla producing same action as that was done with exercise pressor reflex and cause vasodilation wit vagus nerve causing reduction in the blood pressure