affected Many of the victims developed muscular paralysis Following Paintal's

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 This is followed by actual expiration of The air with a very high velocity (may be 500 or 700 km/hr (During cough, owing to great nse of intraptlaural (and hence mediastial pressure) veins (which ara thin walled structures) are severlytd cessatfon of bfood flow through Them no cardiac infow no cardiac outflow (output) cerebral ischemia Recall the brain cannot withstand assaults of anoxafschemia for. say, more than 20 seconds So a severe and prolonged attack of cough may be assocntad with visual black outs and even fainting due to lack of brarn blood supply Cough is beneficial as it causes removal of obnoxous agents from the tracheo bronchial tree However excessive cough, threatening to produce alveolar ruplure/fainting, attack/hemiaton etc should be stopped by anirtussve (cough suppressant) agents Bronchospasm is also to some extent. teleologically benaficlal as il prevents entry of further noxous agents During anesthesia and introduction of