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IB Anatomy Supplemental

This resource explores the heart's myogenic muscle contraction, detailing how heart muscles can contract and relax autonomously, independent of the nervous system. It highlights the role of the SA node, which generates electrical signals that prompt atrial contractions, and the AV node, which coordinates ventricular contractions. Additionally, it explains the heart's response to changes in CO2 levels during exercise, detailing how the medulla in the brain regulates heart rate through signals sent to the SA node, ensuring appropriate adjustments during physical activities.

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IB Anatomy Supplemental

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  1. IB Anatomy Supplemental

  2. Digestive Enzymes

  3. http://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_pumping.htmlhttp://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_pumping.html

  4. Heart Control • Myogenic muscle contraction: heart muscle can contract and relax without nervous system • SA node: tissue sends an electrical signal to stimulate atrial contraction (nearly every second) • AV node: tissue responds to SA node sending an electrical signal to stimulate ventrical contraction 0.1 seconds after it gets SA node signal • These act as the heart’s pacemaker to keep it “in time”

  5. Heart Control • When you exercise, CO2 levels in your blood increase • This increase is sensed by the medulla in your brain which sends a nerve signal through your cardiac nerve to the SA node which increases your heart rate • When you stop exercising, CO2 levels fall, and the medulla sends another signal to the SA node through the vagus nerve to return rate control to the SA node, slowing down the rate.

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