Lecture17_Heart

Lecture17_Heart - The Heart Structure Function LS 2 Prof...

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The Heart: Reading : green pages 493-516 (Ch 12) LS 2 October 15, 2010 Prof. Daniel Lieberman Office Hrs: Tuesday 1-2 And By Appointment ! (really!)
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A typical human heart beats 65 times/ min for ! 75 years = approximately 2.5 billion times
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Tree Shrew 500 million (360 beats/min for 2.6 yrs) Dog 500 million (80 beats/min for 12 yrs) Elephant 600 million (20 beats/min for 57 yrs) In most mammals, the heart beats about 500-600 million times
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But when it ceases to beat… • Causes ! 20% deaths in US • 1.2M new heart attacks each year in US • High blood pressure affects ~50M people in US Yet cardiac disease is virtually unknown in hunter-gatherer populations WHY?
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1. Cardiac anatomy and circulation 2. Cardiac muscle and conduction 4. Cardiac output 5. Healthy hearts (exercise and disease) Today’s lecture:
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The heart is a pump (actually, a double pump) Flow = ! Pressure Resistance Goals: 1. make blood (5.5 L) flow 2. do as little work as possible (keep pressure low) 3. prevent backflow (valves) 4. be adjustable 5. be durable
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The heart develops from a tube (which folds) in the coelomic cavity ( angiogenic cells in splanchnic mesoderm ) Thoracic cavity Abdominal cavity Pelvic cavity
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Lungs : located in pleural cavity of thorax Heart : located in the cardiac cavity located between the lungs and pleural cavity (shifted to left side of body) R Ventricle projects anteriorly but is smaller than more posterior L Ventricle RV supplies pulmonary circulation (from heart to lungs and back) LV supplies systemic circulation (from heart to rest of body and back) RV LV Closely integrated with the lungs
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Human heart (anterior view) - surface anatomy Surrounded by a pericardial membrane Right Ventricle Left Ventricle Right Atrium Superior Vena Cava Aorta (systemic) Pulmonary artery Left Atrium Coronary Arteries Coronary blood flow (supplying heart): ~ 4-5% of total systemic flow Pulmonary veins
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1. Path of blood flow Deoxygenated Oxygenated 1 1 2 3 4 5 5 6 6 7 8 9 10
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2. Valves pressure difference between heart chambers and vessels
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AV valves open when P atrial > P ventricle AV valves close when P atrial < P ventricle LVentricle > P aorta P RVentricle > P pulmon. art. Valves ensure one-way flow left AV is bicuspid (Mitral); right AV is tricuspid * also called semilunar valves* *you don’t need to memorize this mitral tricuspid pulmonary aortic
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(anterior) “superior view” (posterior) fiber optic imaging (r) (l)
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The AV valves have papillary muscles (connected by tendons) to prevent collapse & backflow (prolapse) during ventricular contraction
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Mitral valve prolapse (blood leaks back into the left atrium)
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This note was uploaded on 03/29/2012 for the course LS 2 taught by Professor Andrewa.biewener,petert.ellison,anddaniele.lieberman during the Fall '10 term at Harvard.

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Lecture17_Heart - The Heart Structure Function LS 2 Prof...

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