Lecture 25: Neural Control Of Heart Flashcards
Identify locations of arterial baroreceptors
Carotid sinus
Aortic arch
Name the cranial nerve carrying afferent fibers from each location for arterial baroreceptors
Carotid sinus = nerve IX
Aortic arch = nerve X
Name the CNS location that integrates the afferent nerve traffic from the baroreceptors and mediates reflex response
Nucleus tractus solitary (NTS)
What do both sets of arterial baroreceptors fire in response to?
Stretch
They then initiate reflex to drop BP
What is the Valhalla maneuver ?
Response to force expiration against a closed (or narrowed) glottis, then resumed normal breathing
Describe changes that take place in phase 1 of Valhalla maneuver
Intrathoracic pressure increases (from taking breath)
Aortic pressure rises
BRR = drop in HR
Describe changes that occur in phase 2 of Valsalva maneuver
Venous return drops from high intrathoracic pressure
SV, CO, and BP drop
BRR = rise in HR + vasoconstriction
Fall in BP is arrested!
What happens in phase 3 of valsalva maneuver?
Termination of maneuver
Subject takes breath
Intrathoracic pressure decreases to normal
Thoracic aorta is decompressed = arterial BP dec.
Venous return increases
What happens during phase 4 of valsalva maneuver?
Increased venous return leads to = inc. SV and CO
(Along with previous vasoconstriction) result is “overshoot” of BP
Rise in BP = reflex bradycardia
Describe reflex changes in HR, BP and respiration that occur during diving reflex
Apnea = cessation of breathing
Bradycardia
Peripheral vasoconstriction
Name the facial afferents stimulated by cold water that mediate the diving reflex response
Trigeminal nerve facial receptors (eyes, nose, nasal mucosa)
What is the effect of peripheral vasoconstriction from the diving reflex?
Peripheral vasoconstriction maintains arterial BP despite bradycardia, and diverts CO to heart and brain
