Mechanoreceptors Flashcards
How do mechanoreceptors differ?
Threshold
Range
AP frequency
Sensitivity
Where are arterial baroreceptors found?
Aortic Arch
Carotid sinuses
Coronary arteries
Where are cardiopulmonary mechanoreceptors found?
Cardiac chambers
Veno-arterial regions
Pulmonary arteries
How do carotid sinus baroreceptors relay information?
Via carotid sinus and glossopharyngeal nerves
How do aortic arch baroreceptors relay information?
Via aortic and vagus nerves
What do baroreceptors provide information to?
NTS in medulla oblongata
What is baroreceptor activity influenced by?
MAP
pulse pressure
What does an increase in MAP cause?
Increase of baroreceptor firing
Describe the features of A fibres?
Large diameter
Myelinated
Lower threshold
Has a saturation point
More sensitive
Describe the features of C fibres?
Narrow diameter
Unmyelinated
Still respond at high <AP
What does saturation of A fibres cause?
Recruitment of C fibres
Where are veno-atrial stretch receptors found?
Veno-atrial junctions eg. pulmonary vein and left atrium
What type of fibres are veno-atrial stretch receptors?
Myelinated fibres
What nerve do veno-atrial stretch receptors project through?
Vagal arterial nerve
What increases firing of veno-atrial stretch receptors?
Increase in venous return
Where are cardiac mechanoreceptors found?
Atria and ventricles
What type of fibres are cardiac mechanoreceptors?
Non-myelinated
What nerve do cardiac mechanoreceptors project through?
Vagus and cardiac sympathetic nerve
What fibres are pulmonary artery mechanoreceptors?
Non-myelinated
What do arterial and cardiopulmonary baroreceptors cause?
Net depressor influence on arterial pressure
What do arterial baroreceptors maintain?
MAP
What do cardiopulmonary baroreceptors inhibit?
Arterial pressure
What does stimulation of veno-atrial stretch receptors cause?
Reflex tachycardia
What mediates reflex tachycardia?
Increase in sympathetic outflow to SA node
What does reflex tachycardia produce?
Faster shift of blood to arterial system
What does reduced renal sympathetic nerve activity cause?
Reflex diuresis and natriuresis -> increase in urine output
What is the Bainbridge Reflex?
Tachycardia stimulated by a large rapid infusion of saline into the venous system
What is the Bainbridge reflex triggered by?
Stimulation of veno-atrial stretch receptors and distension of the pacemaker
What are cardiac mechanoreceptors?
Network of fine unmyelinated fibres
Where are cardiac mechanoreceptors found?
Atrial fibres and LV mechanoreceptors
What are atrial fibres triggered by?
Larger atrial distension
What are LV mechanoreceptors triggered by?
Ventricular distension due to filling by preload
What does activation of cardiac mechanoreceptors cause?
Depressor effect
Reflex bradycardia and vasodilation - baroreflex
