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THE HEART

THE HEART. 7.5-7.7. The Heart. Surrounded by fluid-filled membrane called the pericardium to prevent friction Two pumps divided by a septum that are synchronized Right side = receive deoxygenated blood, pumps to lungs

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THE HEART

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  1. THE HEART 7.5-7.7

  2. The Heart • Surrounded by fluid-filled membrane called the pericardium to prevent friction • Two pumps divided by a septumthat are synchronized • Right side = receive deoxygenated blood, pumps to lungs • Left side = receives oxygenated blood from lungs and pumps to body

  3. Chambers of the heart • Four chambers, composed of 2 thinatria (sin. atrium) two thickventricles • Ventricles are more muscular to pump blood to distant tissues • left ventricle has thickest walls, it must force blood throughout body

  4. How blood moves through the heart • Deoxygenated blood moves through veins into the superior & inferiorvenacava • rightatrium bothatria contract  • rightventricle bothventricles contract  • pulmonaryarteries  to lungs (oxygenated)  • pulmonaryveins  left atrium • left ventricle  aorta  to body

  5. Heart Valves • valves prevent blood from flowing wrong way in the heart • Atrioventricular valves  separate atria from ventricles • Semilunar valves  separate ventricles from arteries (half-moon shaped)

  6. Special Arteries • Aorta largestartery • Pulmonary arteries carry blood awayfrom the heart (only one that carries deoxygenated blood) • Coronary arteries  supply heart muscle with oxygen/nutrients (moves away from the heart, back to the heart) • Blocked coronary artery causes angina (heart pains) due to lack of oxygen

  7. Coronary Bypass Surgery • During operation, heart-lung machine takes over • Vein in leg is removed • Vein is attached from aortapastblockage • Another option: bypass with mammary artery • Bypass increasesblood flow to the area served by the coronary artery

  8. Heart Circulation • http://www.intelihealth.com/IH/ihtIH/WSIHW000/8059/8049/317250.html?d=dmtContent

  9. Heart Beats • heart undergo over 3 billion contraction cycles in a lifetime • heart made of myogenic muscle, can contract withoutstimulation • Rhythmic contractions due to two different bundles of nerves • SA node (sinoatrial node), also called pacemaker, starts & keeps heartbeat regular • AV node (atrioventricular node) causes ventricles to contract • AV node passes impulses to 2 large nerve fibres called Purkinje fibres, that branch & carry impulses throughout ventricles

  10. Contraction Of The Heart & Action Of The Nerve Nodes

  11. Electrocardiogram (ECG) measures changes in electrical potential across heart, & can detect contraction pulses • P wave represents contraction of atria • QRS wave is ventricular contraction • T wave signals the ventricles have recovered • ECGs are useful in diagnosing heart abnormalities. • Pg. 260

  12. Cardiac Cycle • Consists of two parts: • Systole = contraction of the heart muscle, blood is forcedout • Diastole = relaxation of the heart muscle, chambersfill with blood • Atria contract while ventricles relax. • Valves in heart open & close during cardiac cycle.

  13. Heart Sounds • Sound of the heart is valves opening & closing produces a characteristic "lub-dub" sound • Atria fill, muscular walls contract, increasing pressure, forcing AV valves to open filling ventricles • Ventricles fill with fluid, they contract • Lub is the closure of the AV valves • Dub is the closing of the SL valves.

  14. The Cardiac Cycle

  15. Hypertension • Hypertension, high blood pressure (the silent killer), occurs when blood pressure is consistently above 140/90. • Causes in most cases are unknown, although stress, obesity, high salt intake, and smoking can add to a genetic predisposition

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