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 intrapt
laural (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 endolracheal tube, if Jocal anesthelrcs (to paralyze this irritant receptors) are not sufficiently used, bronchospasm many develop Similarly, sneezing is also due lo irritation of such receptors in the nasal mucous membrane) So, in short, lung irritant receptors are ardinanly not called into action, when Ihey operate, the rhythm of respiration is severely altered Afferent impulses from these receptors are earned by vagal (afferent) fibers V Peripheral ctomoreceplors Chemoreceptors are present in various anatomical sites of the body and they serve vanous purposes In connection with the control of respiratory1 system we have two types of chenoreceptors, (i) central chemofeceptors (described afterwards), and (ii) penphtral chetmoreceptors etanls ol penpheral chmoreciplors will be given below The following sketches may be noted at present Penpheral chemoreceptors include two sets, (a) cartid body [present at the root of eiiernaf carotid artery fig.4 3 5) and (b) aortic bodies, present in the arch of aorta. They are so placed in the vascular endothelum that they come in direct.cortfacl with the blood They can delect (= analyze) the anenal blood P02 (= Pa02)h PC02 (= Pa C02) and pH When Pa 02 is low, they are stimulated send signals lo the respiratory center respiration stmulated (hyperpnea), by which Pa 02 deficiency is corrected These chetmoreceptors can also sense (= analyze) the PaC02 and when PaCQ3 is high they are ;[stimulaied hyperpnea a correction of PaC02 values However, so far as PaC02 is concerned, central chemoreceptors (not the peripheral ch em o receptors) play the dominant role On the contrary, for Pa02. there is no central chemo receptors and.the. PaO2 correction occurs via the peripheral chemoreceptors. Low blood pH is also sensed by The
laural (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 endolracheal tube, if Jocal anesthelrcs (to paralyze this irritant receptors) are not sufficiently used, bronchospasm many develop Similarly, sneezing is also due lo irritation of such receptors in the nasal mucous membrane) So, in short, lung irritant receptors are ardinanly not called into action, when Ihey operate, the rhythm of respiration is severely altered Afferent impulses from these receptors are earned by vagal (afferent) fibers V Peripheral ctomoreceplors Chemoreceptors are present in various anatomical sites of the body and they serve vanous purposes In connection with the control of respiratory1 system we have two types of chenoreceptors, (i) central chemofeceptors (described afterwards), and (ii) penphtral chetmoreceptors etanls ol penpheral chmoreciplors will be given below The following sketches may be noted at present Penpheral chemoreceptors include two sets, (a) cartid body [present at the root of eiiernaf carotid artery fig.4 3 5) and (b) aortic bodies, present in the arch of aorta. They are so placed in the vascular endothelum that they come in direct.cortfacl with the blood They can delect (= analyze) the anenal blood P02 (= Pa02)h PC02 (= Pa C02) and pH When Pa 02 is low, they are stimulated send signals lo the respiratory center respiration stmulated (hyperpnea), by which Pa 02 deficiency is corrected These chetmoreceptors can also sense (= analyze) the PaC02 and when PaCQ3 is high they are ;[stimulaied hyperpnea a correction of PaC02 values However, so far as PaC02 is concerned, central chemoreceptors (not the peripheral ch em o receptors) play the dominant role On the contrary, for Pa02. there is no central chemo receptors and.the. PaO2 correction occurs via the peripheral chemoreceptors. Low blood pH is also sensed by The
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