Week%209%20-%20Teacher%20Edition

Week%209%20-%20Teacher%20Edition - BIPN 100 Dr. Fortes...

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BIPN 100 Chris Childers Dr. Fortes Winter 09 Match the following to their respective number…. __6___ Ejection __4___ Isovolumetric Contraction __8___ Isovolumetric Relaxation ___3__ Mitral Valve Closes ___1__ Mitral Valve Opens ___5__ Aortic Valve Opens ___7__ Aortic Valve Closes ___9__ Stroke Volume ___2__ Diastolic Filling Cardiac Ouput = Stroke Volume (Volume / Beat) x Heart Rate (Beats per Minute) Normal Heart Rate ~ 70bpm Normal Stroke Volume ~70ml/beat Normal Cardiac Output ~5L / minute What is the starling curve? Law of the heart? How does it relate to stroke volume and cardiac output? Figure 14-28 Starling’s “Law of the Heart” - What if we drink too much water? Don’t drink enough water? How does our body compensate for changing blood volumes? - Increase EDV increase contractility increase stroke volume - This does have a limit; if we stretch too much we see a decrease in tension Figure 14-12 Length Tension Relationship… - The overlap of thin and thick filaments is not perfect; there are portions thin filaments which do not have myosin heads close enough to form cross bridges. As a result…. - When we stretch a sarcomere, we reach a maximum contractility when myosin and actin have perfect overlap and the maximal number of cross bridges, leading to the strongest contraction. - Experimentally, when we stretch a muscle in the lab, the further we stretch it the larger the contraction (within reason…) - As we increase the sarcomere length (as a percentage of maximum) we increase the skeletal muscle tension (physiologically, skeletal muscle is almost always at, or near, it’s maximum) - In the heart, filling the ventricles more, stretching the sarcomeres, leads to very different tensions - For example: at 80% of maximum stretch, tension is only at ~30% of its maximum tension, but at 90% of maximum stretch, tesnsions is at 80% of maximum. Venous return can increase 3 ways…
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Week%209%20-%20Teacher%20Edition - BIPN 100 Dr. Fortes...

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