Cardiopulmonary-R Flashcards
Where are the cardiopulmonary-R?
Atrial-R Veins, espeically veno-atrial junctions Ventricular-R Coronary artery-R Lung stretch-R Lung irritant and J-R Aortic Arch Baro-R
Effect of stimulating atrial-R in dogs?
Diuresis/natriuresis
Increased HR via the Bainbridge reflex. Sympathetically mediated, little input from reduction in PS.
Inhibition of some renal sympathetic nerve firing, but not all.
Cooling vagi to 12degrees abolished response to atrial balloon distension. Afferent arm therefore in vagus.
Suppression ADH release. Also abolished by cooling the vagus.
Compare barorelfex w/ stimulation atrial-R?
Cf BCCO which caused excitation of all sympathetic renal nerves tested, therefore there is convergence of reflexes on certain renal symp nerves.
No convergence on cardiac sympathetic efferent nerves.
Effects of the Bezold-Jarisch reflex? How is the reflex mediated?
Apnoea
Bradycardia
Hypotension
Vagally mediated as atropine blocks the effects.
Apnoea = pulmonary afferents
Bradycardia and hypotension = cardiac afferents
Effects of lung inflation?
Hering-Breuer Relfex (1868)
Lung inflation inhibits ongoing inspiration
Vasodilation and fall in systemic vascular resistance
Graded
Abolished by cutting pulmonary branch of vagus
Effect on lung inflation on HR?
Low pressure (6mmHg)-> tachycardia Higher pressures -> ? variable
Higher pressures activate HB reflex, which inhibits central respiratory drive which disinhibits CVMNs -> reduction in HR
Are there mechanoreceptors in the ventricles and coronary arterys?
Ventricles, unlikely
Coronary arteries, yes, more sensitive than CS and have a long lasting effect on systemic vascular resistance but no significant effect on HR.
How can blood flow to the heart and therefore stimulation of cardiopulmonary receptors be altered?
Standing upright Head down tilt LBNP LBNP + tilt Standing/sitting in water
