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12 Cards in this Set
- Front
- Back
What is the fundamental morphological unit of cardiac muscle?
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Sarcomere
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TRUE/FALSE - The heart generates tension via the shortening of its muscular fibers, which is manifest as the ejection of a volume of blood.
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False - heart generates pressue not tension
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Describe the concept of Preload.
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Preload is the force necessary to stretch the relaxed muscle to its initial length.
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Why is Preload important?
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The degree of initial stretch effects the muscle's ability to stretch upon stimulation.
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TRUE/FALSE - Maximal Resting Sarcomere length is around 2.2 microns
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True
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Diastolic ventricular function can be thought of as chamber compliance or distensibility. What are the major determinants of compliance?
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The active process of muscular relaxation and the passive elastic properties of the left ventricle which define the intrinsic stiffness of cardiac muscle are the major determinants.
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Describe isotonic contractions.
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An isotonic contraction is a contraction which occurs with no load on the muscle in which developed force is negligible and velocity of shortening is maximal.
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Describe isometric contractions.
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An isometric contraction occurs when the muscle is stimulated to contract against a load and no shortening occurs so that developed force is maximal and velocity of shortening is negligible
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Afterload is determined largely by (blank) and impedance to (blank).
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PVR and ventricular ejection
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TRUE/FALSE - Contractility is a change in cardiac function independent of variation in AL & PL.
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True
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Describe the concept of Afterload.
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The tension, force or stress (force per unit of cross-sectional area) acting on the fibers in the ventricular wall after the onset of shortening.
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Cardiac Output = HR x ?
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Stroke Volume
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