Cardiovascular Physiology 23 Flashcards
What does the Frank-Starling Mechanism state?
The SV increases as the EDV increases
What is the equation for CO?
SV * HR
How much do the ventricles empty when they contract?
50-75%
What is Contractility?
The strength of contraction at any given EDV
How does Contractility affect CO?
As the ventricles contract harder, they will pump out more blood
How does increase sympathetic stimulation affect myocardium?
It will increase the strength of contraction of the ventricular myocardium, increasing stroke volume and cardiac output
Which receptors does the Sympathetic neurotransmitter norepinephrine act on?
Beta adrenergic receptors
How do the sympathetic neurotransmitters increase ventricular contractility?
They act on beta adrenergic receptors to increase contractility
What kind of innervation does the ventricular myocardium receive?
Sympathetic innervation
How can Parasympathetic activity affect the heart rate?
Through its effects on the SA node and not the stroke volume
What are the increased contractility and stroke volume induced by Sympathetic innervation independent of?
EDV
How does the Frank-Starling mechanism and the sympathetic stimulation co-exist to affect stroke volume?
The Frank-Starling mechanism is dependant of the EDV and increases based on that but sympathetic stimulation increases SV independent of EDV both work to increase contractility
How does increased contractility affect the ejection fraction?
Increased contractility leads to increased ejection fraction
What is the ejection fraction equation?
Ejection fraction (EF) = SV/EDV
What does sympathetic stimulation do to ejection fraction?
Sympathetic stimulation increases Ejection fractions
