McCumbee - Regulation Of Cardiac Function Flashcards
Location of primary regulatory areas of cardiovascular function
Medulla
Integrative area for coordinating various cardiovascular responses
Hypothalamus
Modulates cardiovascular function by means of projections into the integrative areas of the hypothalamus
Cerebral cortex
Sensory area located in the ________ has interneurons which modulate activity of cardiac inhibitory, cardiac accelerator, and vasoconstrictor areas
Nucleus tractus solitarius
Sensory fibers going to the nucleus tractus solitariues come from ?
Baroreceptors and chemoreceptors
Contains neurons involved in controlling sympathetic output to the heart and blood vessels.
Rostral ventrolateral medulla
An increase in teh activity of the nucleus tractus solitarius will _______ vagal efferent activity and decrease sympathetic efferent activity
Increase
Stimulation of areas within the rostral ventrolateral medulla stimulates
Vasoconstriction, tachycardia, and cardiac contractility
Neurons controlling sympathetic output to the heart and blood vessels (in the RVLM) are tonically active. Inhibitory interneurons from the _____ inhibit the tonically activated neruns
Nucleus tractus solitarius
When the dorsal vagal nucleus and the nucleus ambiguus of the medulla are electrically stimulated, they elicit
Bradycardia
Cardioinhibitory center (stimulation elicits bradycardia)
Dorsal vagus nucleus and nucleus ambiguus
The nuclei that make up the cardioinhibitory center are the
Dorsal vagal nucleus and the nucleus ambiguus
What accounts for the fact that the normal heart rate is well below the intrinsic firing rate of the SA node?
The tonically active state of the cardioinhibitory center (nucleus ambiguus and dorsal vagal nucleus) which at baseline is causing bradycardia
Parasympathetic innervation that goes to the heart comes from the dorsal vagal nucleus and nucleus ambiguus of the medulla. The ganglia for there are near __
The SA and AV nodes
The right vagus primarily inhibits the
SA node
The left vagus primarily inhibits the ____-
AV node
____ muscle is innervated by vagal efferents, whereas the ______ myocardium has only sparse vagal innervation
Atrial
Ventricular
Parasympathetic Postganglionic fibers mediate vagal action by releasing _______
Acetylcholine
Why does parasympathetic postganglionic innervation decay rapidly in the SA and AV nodes?
It uses ACh, and there is a high cholinesterase concentration around those nodes which acts to break down the stimuli
Neurons within the _____ have a tonic stimulatory effect on the heart and blood vessels
RVLM
In the heart, postganglionic sympathetic adrenergic nerves innervate
The SA and AV nodes, conduction pathways and myocardium
What type of stimulation to the heart decays faster, sympathetic or parasympathetic?
Parasympathetic.
The vasoconstrictor effects of sympathetic nerves to blood vessels are mediated by _________ fibers
Noradrenergic
Fibers that release norepinephrine
Most important adrenergic receptor w/ respect to modulating cardiac function
Beta -1
Adrenergic receptors that are found in the heart
Beta-1
Beta-2
Alpha-1
Order of functional potency in adrenergic receptors in the heart ?
Beta1 > beta2 > alpha1
In the heart, ACh binds to ________
M2 Muscarinic receptors
In the heart, activation of M2 muscarinic receptors (by the binding of ACh) induces dramatic NeGaTivE _____ and _____ effects
Chronotropic and dromotropic
Also induces a modest negative inotropic effect, mostly on the atria
Sympathetic stimulation of the heart induces positive
(This is by norepinephrine binding beta1 and beta2 and alpha1 receptors_
Positive chronotropic, inotropic, and dromotropic effects
What is atropine?
A muscarinic receptor antagonist. So it blocks the binding of muscarinic receptors by ACh, keeping there from being parasympathetic response to the heart, with the net result of increasing inotropy, chronotropy, and dromotropy.
What is propranolol?
A beta-adrenergic receptor antagonist. Blocks binding of norepinephrine to beta 1, beta2 receptors. This results in a net decrease in chronotropy and dromotropy, and inotropy.
What are baroreceptors?
Stretch receptors found in the walls of the heart and blood vessels and are stimulated by distention.
Abundant in carotid sinus and aortic arch
Impulses from the baroreceptors in the carotid sinus are transmitted to the nucleus tractus solitarius of the medulla via the ?
Glossopharyngeal nerve
Impulses from the baroreceptors in the aortic arch are transmitted by ?
The vagus nerve
Baroreceptors are tonically active. Baroreceptor firing ______ with increasing blood pressure and _______ with decreasing blood pressure
Increases
Decreases
