Heart Ch 18 web - The Heart = pump of the cardiovascular...

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Figure 18.1c (c) Superior vena cava Left lung Aorta Parietal pleura (cut) Pericardium (cut) Pulmonary trunk Diaphragm Apex of heart The Heart = pump of the cardiovascular system
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The Heart is about fist sized Located in thorax between lungs (inferior mediastinum ) Oriented with apex (point) toward left hip, base (top) toward right shoulder Point of maximal intensity (PMI) Diaphragm Sternum 2nd rib Midsternal line base apex
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The Heart is covered by membranes Figure 11.1a–b Pericardium —a double-walled sac Outer sac = 2 layers Fibrous pericardium – loose, superficial, fibrous Parietal pericardium – slippery, serous membrane Inner sac = visceral pericardium (hugs heart) a.k.a. epicardium - slippery serous, first layer of heart wall Serous fluid lubricates space between layers
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Heart Wall = 3 tissue layers Figure 11.2b Epicardium – connective tissue serous membrane Myocardium – middle cardiac muscle (mainly) layer Endocardium – inner epithelium tissue (a.k.a. endothelium)
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Cardiac muscle anchored by fibrous skeleton in myocardium Cardiac muscle bundles Supports major blood vessels – prevents excessive stretch Ensures specific electrical conduction paths (more later)
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The Heart has 4 chambers Separated into right ( O 2 poor ) and left ( O 2 rich ) sides Atria = blood receiving chambers Right atrium – O 2 poor blood from body Left atrium – O 2 rich blood from lungs Ventricles = discharge chambers Right ventricle – sends O 2 poor blood to lungs ( pulmonary circuit) Left ventricle – sends O 2 rich blood through systemic circuit (rest of body)
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Right and Left Ventricles – 2 pumps Figure 11.4 Right ventricle is crescent shaped – wraps around left Left ventricle is circular, more powerful than right – forces blood through longer pathway Separated by interventricular septum = interatrial septum between atria
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Heart Valves prevent backflow of blood Atrioventricular (AV) valves— between atria and ventricles Bicuspid (mitral) valve (left side) Tricuspid valve (right side)
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Figure 11.5a, step 1 Returning blood fills relaxed atria and ventricles (open AV valves) Ventricles Operation of the AV valves AV valves open (a)
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Figure 11.5a, step 2 Returning blood fills relaxed atria and ventricles (open AV valves) Atria contract – more blood forced into ventricles Relaxed Ventricles Operation of the AV valves AV valves open (a)
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Figure 11.5a, step 4 3. Ventricles contract, blood forced against AV flaps / into arteries 4. AV valves close preventing backflow to atria (LUB of LUB- dup sound) (a) Operation of the AV valves Chordae tendineae prevent valve flaps from everting
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Semilunar valves prevent arterial blood from reentering ventricles Figure 11.2c Pulmonary semilunar valve – right side Aortic semilunar valve – left side Both Open as ventricles contract and AV close 3 flaps/leaflets each
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As ventricles contract
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This note was uploaded on 01/13/2012 for the course ANATOMY 2B taught by Professor Prestongalusky during the Fall '11 term at Riverside Community College.

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Heart Ch 18 web - The Heart = pump of the cardiovascular...

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