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CARDIOVASCULAR SYSTEM

CARDIOVASCULAR SYSTEM . Introduction. Fully formed by the 4 th week of embryonic development Hollow Muscular Organ That Acts as a Double Pump Continuous pump - once pulsations begin, heart pumps endlessly until death . Heart Anatomy . General

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CARDIOVASCULAR SYSTEM

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  1. CARDIOVASCULAR SYSTEM

  2. Introduction • Fully formed by the 4th week of embryonic development • Hollow Muscular Organ That Acts as a Double Pump • Continuous pump - once pulsations begin, heart pumps endlessly until death

  3. Heart Anatomy General Size: approximately the size of a person’s fist Coverings: Pericardium Double layered sac Contains 10 – 20 cc. Of pericardial fluid to reduce the friction of the beating heart Heart Wall Myocardium: heart muscle; thicker on left side of the heart Endocardium: lining of heart chambers; endothelial tissue continuous with the lining of the blood vessels

  4. Chambers Atria • 2 upper chambers of heart Thin walls, smooth inner surface • Responsible for receiving blood • Right atrium receives deoxygenated (oxygen poor) blood from the body through the superior and inferior vena cava • Left atrium receives oxygenated (oxygen rich) blood from the lungs through the pulmonary veins • 2 lower chambers of the heart • Thicker walls, irregular inner surface • Responsible for pumping blood away from the heart • Right ventricle sends deoxygenated blood to the lungs via the pulmonary arteries • Left ventricle sends oxygenated blood to all parts of the body via the aorta Ventricles

  5. Accessory Structures Septum: muscular wall dividing the heart into right and left halves Heart valves – prevents the backflow of blood Papillary muscles prevent heart valves from turning inside out when ventricles contract Chordaetendineae prevent heart valves from turning inside out when ventricles contract

  6. Great Vessels • Superior and inferior vena cava: receive deoxygenated blood from all parts of the body • Pulmonary arteries: carry deoxygenated blood to the lungs from the right ventricle • Pulmonary veins: carry oxygenated blood to the left atrium from the lungs • Aorta: carries oxygenated blood to distribute to all parts of the body

  7. Valves • Tough fibrous tissue between the heart chambers and major blood vessels of the heart • Gate-like structures to keep the blood flowing in one direction and to prevent regurgitation or backflow of blood • Tricuspid valve: between the right atrium and the right ventricle • Bicuspid/mitral valve: between the left atrium and the left ventricle • Pulmonary semilunar valve: between the right ventricle and the pulmonary arteries • Aortic semilunar valve: between the left ventricle and the aortic arch/aorta • Heart Sounds • When the AV (atrioventricular) and semilunar valves close, they make the sound heard as “lub-dub” (auscultated with stethoscope) • d. Abnormal heart sounds = murmur; valve pathology

  8. Pathway of Blood Through the Heart and All Body Tissues • Superior and inferior vena cava • Right atrium • Tricuspid valve • Right ventricle • Pulmonary semilunar valve • Pulmonary arteries • Lungs – (O2 and CO2 exchange - external respiration) • Pulmonary veins • Left atrium • Bicuspid/Mitral valve • Left ventricle • Aortic semilunar valve • Aorta - all parts of body via arteries • Arterioles • Capillaries of individual tissues (O2 and CO2 exchange = internal respiration) • Venules • Veins • Superior and inferior vena cava

  9. Cardiac Cycle • Right and left sides beat together • Electrical impulses in the heart cause the myocardium to contract in a cyclic manner • Cycle consists of a brief period of rest called diastole followed by a period of ventricular contraction • At the start of a cycle, the atria contract pushing blood into the ventricles • Then the atria relax • Blood returning from the body enters the right atrium • Blood returning from the lungs enters the left atrium

  10. Continued cardiac cycle • While the atria are filling, systole begins and the ventricles contract • Right ventricle pushes blood into the pulmonary artery so it can go to the lungs for oxygen • Left ventricles pushes blood into the aorta so it can be carried to all parts of the body

  11. Last of cardiac cycle • Blood in the right side of the heart is low in oxygen and high in carbon dioxide • When it gets to the lungs, the carbon dioxide is released into the lungs and oxygen is taken into the blood • Oxygenated blood is then carried to the left side of the heart by the pulmonary veins • Now the blood in the left side of the heart is high in oxygen and low in carbon dioxide and ready to be carried to body cells

  12. Conduction pathways Electrical impulses originating in the heart cause the cyclic contractions of the muscles Starts at the SA node (sinoatrial), also called the pacemaker of the heart -a group of nerve cells in the right atria sends electrical impulses that spread over the muscles in both atria -causes atria to contract -after the electrical impulse passes through the atria, it reaches the AV node (atrioventricular) -The AV node picks up the impulse at a group of nerves cells located between the atria and the ventricles -It sends electrical impulses through nerve fibers into the septum called the bundle of His

  13. More on conduction pathways Bundle of His divides into the right and left bundle branch Right and left bundle branches -pathways that carry the impulse down through the ventricles -bundles subdivide into a network of fibers throughout the ventricles called the Purkinje fibers Purkinje fibers -spread electrical impulse to all of the muscle tissue in the ventricles -causes the ventricles to contract Electrical conduction pattern occurs approximately every 0.8 seconds Movement of the electrical impulse can be recorded on an (ECG)

  14. Blood Vessels • Arteries • Carries blood away from the heart • Are more muscular and elastic than other blood vessels • Aorta is the largest artery • Receives blood from the left ventricle • Immediately begins branching into smaller arteries

  15. Blood vessels • Smallest branches of arteries are arterioles • They join the capillaries • Capillaries • Connect arterioles and venuoles, the smallest of veins • Have thin walls • Allows oxygen and nutrients to pass through to the cells • At the same time carbon dioxide and metabolic (waste) products from the cells enter the capillaries

  16. Blood Vessels • Veins are blood vessels that carry blood back to the heart • Veins are thinner than arteries • Most contain valves that prevent backwards flow of blood • Venules • Smallest of veins • Connect to capillaries • Venuoles join together and become larger to form veins

  17. Blood vessels • Superior and inferior vena cava • Two largest veins • Superior brings blood back from the upper part of the body • Inferior bring blood back from the lower part of the body

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