PNB 2265 Lecture Notes - Lecture 10: Vagus Nerve, Stroke Volume, Cardiac Output

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The second heart sound (S2,
"dupp"), occurs:
During atrial systole
During early ventricular
After late ventricular
o Closing valves
After late ventricular diastole
Wigger’s Diagram
Cardiac Output
Cardiac output
o Stroke volume
Heart rate (beats/min)
o ~6L per min
Modulation of CO
Variations in heart rate and
stroke volume change cardiac
Heart Rate
Doesn't need any myocytes
Pace maker are innervated autonomic and are adrenergic hormones
o Epi and norepi can change
o Innervated by sympathetic and parasympathetic
Autonomic Innervation (Both Innervate Pacemaker Cells)
o Cardiac nerve
Adrenergic neurons
Release epi onto pace maker cells
o Cardioacceleratory center
o NE
o Can control both stroke volume and heart rate speed
o Vagus nerve
o Cardioinhibitory center
o ACh
Constantly released to slow down AP
o Decrease cAMP and decrease pace
o If you block parasympathetic: increase in basal heart rate in a person
o Not good at changing stroke volume, only heart rate
The vagus nerve decreases heart rate by decreasing the rate of SA node filling
Acceleration: GPCRs
Catecholamines: epinephrine, norepinephrine
In the heart, NE/E bind beta adrenergic receptors G-protein coupled receptors (Gs)
Beta Receptors on Heart to Respond to Epi and Norepi***
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