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The Heart: Center of the Circulatory System

Discover fascinating facts about the heart, its structure, functions, and common diseases. Explore the cardiac conduction system and understand the different types of blood vessels. Learn about the crucial role of blood in transporting nutrients, gases, and other vital components throughout the body.

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The Heart: Center of the Circulatory System

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  1. The Heart

  2. FUN FACTS • Center of the circulatory system • Beats over 100,000x/day • Pumps 1835 gallons/day • Study of the heart and accompanying diseases • cardiology

  3. Heart lies within the mediastinum • Center of chest • 2/3 lies to the left of the mediastinum

  4. Pericardium • Prevents overdistension of the heart • Anchors heart within mediastinum

  5. Three layers to the heart • Epicardium: outer layer • Myocardium: middle layer made up of cardiac muscle • Endocardium: inner lining of the heart, covers valves and the tendons that hold valves open

  6. What is??? • Epicarditis • Myocarditis • Endocarditis

  7. Four Chambers • 2 atria (singular is atrium): holding chambers of heart • 2 ventricles: pump blood out of heart to body

  8. Blood Vessels • Superior vena cava: brings oxygen-poor blood to heart from upper portions of body. • Inferior vena cava: brings oxygen-poor blood to heart from lower portions of body • Right and left pulmonary arteries: brings oxygen-poor blood from heart to lungs • Right and left pulmonary veins: brings oxygenated blood from lungs back to heart

  9. Question??? • How are pulmonary arteries and pulmonary veins different from all other arteries and veins in your body?

  10. Valves • Atrioventricular (AV) valves or cuspid valves: between atria and ventricles • Tricuspid: on right side of heart • Bicuspid: on left side of heart • Semilunar valves: between ventricles and arteries leaving heart • Pulmonary semilunar valve • Aortic semilunar valve

  11. Circulatory Problems • Ischemia: reduced oxygen. Weakens but does not kill heart cells • Angina pectoralis: chest pain due to ischemia • Causes: • Stress • Over exertion • Artherosclerosis • Fever • anemia

  12. Myocardial Infarction • Heart attack • Infarction: death of tissue due to interrupted heart flow

  13. Conduction System • Your heart is innervated by the autonomic nervous system, but only to regulate speed of contractions • Heart has an internal conduction system • Sinoatrial Node (SA node): special heart tissue that causes heart to contract

  14. A Cut To The Heart

  15. SA node • Called the “pacemaker” • Self excitation about 75 times/minute • Located in the right atrial wall just below superior vena cava opening • Initiates excitation…spreads to both atria. • Causes them to contract

  16. After spreading to atria • AV node and bundle of His distribute impulse to ventricles via Purkinje fibers

  17. Blood Vessels

  18. The 3 major types of vessels Arteries – carry blood away from the heart Veins – carry blood toward the heart Capillaries – contact tissue cells (Serving cellular needs)

  19. Capillaries ·Very narrow (10 µm diameter, the red blood cells that travel through capillaries are 6 µm in diameter).

  20. Blood

  21. Functions • Transports • Dissolved gasses • Nutrients • Waste products to lungs and kidneys • Enzymes • Hormones from endocrine organs

  22. Functions • Regulates • pH • Electrolyte concentration of body fluids • Body temperature • Restricts fluid loss • Defends pathogens and toxins

  23. Components • Blood is the body’s only fluid tissue • It is composed of liquid plasma and formed elements • Plasma (55%) • 90% water • minerals, sugars, lipids, hormones, proteins (fibrinogen, and albumen) • Formed elements (45%) include: • Erythrocytes, or red blood cells (RBCs) • Leukocytes, or white blood cells (WBCs) • Platelets

  24. Physical Characteristics and Volume • Blood is a sticky, opaque fluid with a metallic taste • Color varies from scarlet (oxygen-rich) to dark red (oxygen-poor) • The pH of blood is 7.35–7.45 • Blood accounts for approximately 8% of body weight • Average volume of blood is 5–6 L for males, and 4–5 L for females

  25. Blood maintains: • Appropriate body temperature by absorbing and distributing heat • Normal pH in body tissues using buffer systems • Adequate fluid volume in the circulatory system

  26. Protection • Blood prevents blood loss by: • Activating plasma proteins and platelets • Initiating clot formation when a vessel is broken • Blood prevents infection by: • Synthesizing and utilizing antibodies • Activating complement proteins • Activating WBCs to defend the body against foreign invaders

  27. Erythrocytes (RBC’s)

  28. Erythrocytes • Biconcave discs & anucleate allow for a huge surface area to volume ratio • Hematocrit – percentage of RBCs out of the total blood volume. (Ave) 46 adult men & 42 adult women. • There are roughly 5 million RBCs in each microliter of blood; they transport oxygen and carbon dioxide, and have large surface-to volume ratios. • Red blood cells account for slightly less than half the blood volume.

  29. Erythrocytes • Erythrocytes are unable to perform normal maintenance operations and usually degenerate after about 120 days in the circulation. • Each red blood cell contains molecules of hemoglobin (Hgb), which can reversibly bind oxygen.

  30. Leucocytes (White Blood Cells) • Nuclei • No hemoglobin • Functions: • leucocytes are phagocytic - What does that mean? • effective against bacteria, viruses, fungi, transplanted cells and cancer cells

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