J reflex = stimulation of J receptor bradycardia + hypotension + hyperpnea + weakness of skeletal muscles When are these

probably in the walls of the alveoli, when stimulated they produce apnea (= stoppage of respiration) followed by hyperpnea. bradyeardia and hypotension In addition. 11 can also produce bronchospasm Further, stmulation of J receptors Ie ads to the inhibition of contraction of the skeletal muscles Therefore. J reflex = stimulation of J receptor bradycardia + hypotension + hyperpnea + weakness of skeletal muscles When are these receptors stimulated? Answer is, it is slimulaied in pathological conditions like, (i) sma emboh in the pulmonary blood vessels and (ii) pulmonary edema J receptors and muscular exercise What causes the physical exhaustion and muscular fatigua during a hard exercise is not clearly known (In general, it is believed that fatigue in intact man is caused by central mechanism, ie . mechanism residing in the synapses of the central nervous system) Paintil argued that during muscular exercise. cungestion of the pulmonary capillaries lead to slight accumulation of interstitial fluid (recall, at health during rest, the pulmonary interstium is dry) this in turn Ie ads to stimulation of J receptors muscular weakness Teteologically, this may be viewed as a naturally exsting 'brake'mechanism in the body, operating to prevent excessive exercise However, paintals vews regarding the cause of muscular weakness in physical exercise is yei to be univsrsally agreed Towards the end of 198J. a ryeal iragedy, called Bhopal Gas Tragedy'occurred m Bhopal oMndia In this tragedy, poisonous gas leaked out from a factory and great many people were affected Many of the victims developed muscular paralysis Following Paintal's line of argument, it can be suggested that This can be due to the stimulation of the J raceptors by the gas Afferent fibers from [ht J nctpton are carried by thi vagus iV Lung irntant receptors Thess are present in the epthelial layer (in between the epthelial ceils. to bt precise) throughout the tricheo bronchial tree (but upto the respiratory bronchiole) They are stimulated by cigarette smoking, industrial pollutants like S02 and imtant gaas Thers is a suggestion that during asthmatic allacks they are stimulaied by histamme (recall mast cell' dtslabtlzation and release of hitarrane itend to occur with very slight provocation in asthmatics) Effects may be of two types i) if the receptors of trachea/bigger bronchi are stimulated the response is cough ii) if the receptors of smaller or smallest bronchi are stimulated, the effect is bronrhospasm Cough In Ihe intial phase of cough, there is a catch (an inspiratory catch) followed by violent expiralory effort with Ihe glollis closed Ai this phase the inliapleural pressure nses tremendously (may reach figures like 7O or 8O mm Hgi and the alveol have to withstand a tremendous pressure