Regulation of Cardiac Function Flashcards
What regions of the CNS regulate cardiovascular function?
Medulla - location of primary regulatory areas of CV function
Hypothalamus - integrative area for coordinating CV responses
Cerebral Cortex - modulates CV function
What is the functions of the nucleus tractus solitarius of the medulla?
Receives sensory innervation from CN IX and X, including baroreceptors and chemoreceptors
Modulate cardiac inhibitory, accelerator and vasoconstrictor areas
What is the function of the ventrolateral medulla?
Contains neurons involved in controlling sympathetic output to the heart and blood vessels
Stimulation induces vasoconstriction, tachycardia and cardiac contractility
Sympathetic output is tonically active
Describe the projections of the NTS?
Inhibitory interneurons to the sympathetic neurons in the ventrolateral medulla
Excitatory interneurons to the vagal neurons in the dorsal vagal nucleus and nucleus ambigguus
What occurs when the dorsal vagal nucleus and nucleus ambiguus are stimulated?
Elicit bradycardia
Sometimes called the cardioinhibitory center
Under resting conditions these nuclei are tonically active, accounts for the fact that the normal heart rate is well below the intrinsic firing rate of the SA node
What is the primary function of the left and right vagus?
Left vagus - primarily inhibits AV conduction
Right vagus - primarily inhibits SA conduction
What do postganglionic sympathetic adrenergic nerves innervate in the heart?
SA and AV nodes
Conduction pathways and the myocardium
What mediates the vasoconstrictor effects of sympathetic nerves to blood vessels?
Noradrenergic fibers
What is chronotropy?
Heart rate
What is dromotropy?
Conduction Velocity
What is the most important receptor in modulating cardiac function?
B1 receptor activation
What does ACh bind to in the heart?
M2 muscarinic receptors
Induces dramatic negative chronotropic and dromotropic effects
What division of the autonomic nervous system is the predominating influence on heart rate?
Parasympathetic
What are baroreceptors?
Stretch receptors stimulated by distention
Abundant in the carotid sinus and aortic arch
Monitor changes in arterial pressure
How do baroreceptors respond to changes in blood pressure?
Tonically active at normal BP
Increase firing with increasing blood pressure and decreases with decreasing blood pressure
