Lecture 6 - 1 NPB113 Contractile Properties of the Heart...

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Unformatted text preview: 1 January 24, 2010 NPB113 Contractile Properties of the Heart 6-1 Outline • Definition of Terms • Intrinsic contractile properties of the heart – Heterometric autoregulation (Frank- Starling) – affect of changes in preload – muscle fiber length – Homeometric autoregulation – affect of changes in afterload, aortic diastolic pressure, on contractile properties of the heart. • Extrinsic Influences on the contractile properties of the heart • Details of Heterometric Autoregulation using the Cardiac Cycle • Homeometric Autoregulation using the Cardiac Cycle • Assessing affects of intrinsic and extrinsic affects on the contractile properties of the heart using – Cardiac Function Curves – Effect of change in muscle fiber length & Contractility. – Pressure – Volume Loops – Effect of changes in Muscle Fiber Length & Contractility 2 January 24, 2010 NPB113 Contractile Properties of the Heart 6-2 Definition of Terms Translation of Terms from Cardiac Muscle to the Contraction of the Whole Heart – Muscle fiber length = End Diastolic Volume (EDV) – Preload = End Diastolic Pressure (EDP) = End Diastolic Volume . EDV = End Systolic Volume + Venous Return . – Afterload = Aortic or Arterial Diastolic Blood Pressure (ADP) – Total Load = Preload + Afterload = EDP (or EDV) + ADP . – External Shortening = Stroke Volume (SV) Auxotonic Contraction – External shortening (ejection of the SV) with continued increase in tension or pressure. – Therefore, contraction of the heart is not isometric nor is its isotonic during the ejection of the SV. – For the heart, isovolumetric contraction has some characteristics of the isometric phase of an isotonic contraction because there is an increase in pressure but no change in volume (there is a change in heart 2 January 24, 2010 NPB113 Contractile Properties of the Heart 6-2 Definition of Terms Translation of Terms from Cardiac Muscle to the Contraction of the Whole Heart – Muscle fiber length = End Diastolic Volume (EDV) – Preload = End Diastolic Pressure (EDP) = End Diastolic Volume . EDV = End Systolic Volume + Venous Return . – Afterload = Aortic or Arterial Diastolic Blood Pressure (ADP) – Total Load = Preload + Afterload = EDP (or EDV) + ADP . – External Shortening = Stroke Volume (SV) Auxotonic Contraction – External shortening (ejection of the SV) with continued increase in tension or pressure. – Therefore, contraction of the heart is not isometric nor is its isotonic during the ejection of the SV....
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This note was uploaded on 04/09/2010 for the course NPB npb 113 taught by Professor Goldberg during the Spring '10 term at UC Davis.

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Lecture 6 - 1 NPB113 Contractile Properties of the Heart...

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