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Understanding Heart Anatomy, Circulation, and Function

This overview delves into the anatomy and functioning of the heart, highlighting its four chambers—two atria and two ventricles—each playing a vital role in blood circulation. It describes the movement of deoxygenated blood from the body to the lungs and the return of oxygenated blood back to the body. The importance of heart valves, the role of the SA and AV nodes in regulating heartbeat, the mechanics of the cardiac cycle, and the implications of hypertension are also discussed. This comprehensive guide is essential for understanding cardiovascular health.

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Understanding Heart Anatomy, Circulation, and Function

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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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