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Circulation and Defense

Circulation and Defense. Circulatory System. Background. Closed system vs. open systems. Blood Vessels. Arteries Veins Capillaries. Blood Vessels. Arteries - away from heart -Thick elastic walls – why? - withstand pressure - Branch into arterioles

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Circulation and Defense

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  1. Circulation and Defense

  2. Circulatory System

  3. Background • Closed system vs. open systems

  4. Blood Vessels • Arteries • Veins • Capillaries

  5. Blood Vessels Arteries - away from heart -Thick elastic walls – why? - withstand pressure - Branch into arterioles - smaller arteries

  6. Specific Arteries • Aorta - largest artery – 2.5cm in diameter - extends from left ventricle of heart • Carotid - from aorta to head - internal to brain, external to face - have chemoreceptors to detect pH

  7. Specific Arteries cont’d • Coronary - branch off aorta & lead back to heart muscle • Brachial - extends from aorta to arms • Hepatic - from aorta to liver • Femoral - from aorta to legs • Renal - from aorta to kidneys

  8. Veins • To heart • Thinner walls w/ some elastic • Valves to prevent backflow • Venules branch from capillaries to veins

  9. Specific Veins • Inferior Vena Cava - from lower body to right atrium - all veins from lower body lead here - 3cm in diameter • Superior Vena Cava - from head to rt. atrium

  10. Specific veins cont’d • Jugular veins - from brain & face to superior vena cava

  11. Capillaries • One cell thick • Site of gas exchange b/w cells & blood • Fluids from tissues re-enters blood due to hypertonicity (increased plasma protein concentration) • Edema – swelling of tissue – water retention

  12. The Heart 2 pathways of circulation - pulmonary circulation - b/w heart & lungs blood becomes oxygenated at lungs - systemic circulation b/w heart & all body parts blood drops off O2, picks up CO2 Path of blood through heart – see diagram

  13. Features of the Heart Made of cardiac muscle (cross striated) Heartbeat has 2 parts 1. Systole - contracting of muscle - ventricles push blood out 2. Diastole - relaxed - atria filling up

  14. Heart action • Both atria fill simultaneously - A-V valves closed - semilunars closed • A-V valves open as atria contract • Ventricles fill and A-V valves forced shut • Semilunars open as ventricles contract • Blood pushed into arteries semilunars forced to close • Lub-dupp sound is closing of valves

  15. Regulation of Heartbeat • Heart beats w/o control from CNS • Contractions coordinated by sinoatrial node(S-A node) AKA pacemaker - located in rt. atrium - made of cells that spontaneously initiate electrical impulses

  16. Steps of heart beat - Pacemaker initiates impulse - Electric current spreads across both atria causing them to contract - A-V node in rt. Atrium hit by impulse - A-V node stimulates ventricles to contract

  17. Regulation of Pacemaker • Medulla sends messages (hormones) to change heart rate - epinephrine aka adrenaline causes  heart rate - temperature causes  heart rate

  18. Regulation of blood flow • Flow is not even to all parts • Smooth muscles in arterioles constrict & relax thus changing blood flow • Vasodilation - muscles relax & dilate thus  blood flow • Vasoconstriction – muscles contract & constrict the arteriole thus  blood flow • i.e. - after eating

  19. Blood Pressure • Greater the pressure the greater the flow • Negative feedback regulates pressure • Stretch receptors in aorta & carotids • If pressure  the heart rate should  & blood vessels should dilate • If pressure  the heart rate should  & vessels should constrict

  20. Blood Pressure cont’d • Hypertension – high blood pressure - dilation doesn’t occur - medication helps dilate vessels

  21. Functions of Blood • Transport - O2 - CO2 and other wastes - nutrients, hormones, electrolytes • Regulates pH • Regulates temperature

  22. Components of Blood • 2 parts of whole blood 1. Plasma – liquid 55% 2. Cellular part – solid 45% • 4-6 L in ave. person

  23. Plasma • 90% water • 10% - substances moving from place to place ie, nutrients, hormones - electrolytes – dissolved ions osmotic balance & pH balance (7.4)

  24. Plasma cont’d • Plasma proteins - enzymes - immunoglobulins – antibodies - fibrinogens – clotting - when these proteins are gone the plasma is called serum

  25. Red Blood Cells • Aka erythrocytes • Most numerous • Made in bone marrow • Carries O2 - hemoglobin binds w/iron • No nucleus when mature

  26. White Blood Cells • 1 WBC for every 1,000 RBC • Larger than RBC’s • Defends against foreign particles • Made in bone marrow • Mature in spleen, thymus, tonsils, adenoids & lymph nodes

  27. WBC’s cont’d • Different types of WBC’s - macrophages – eating phagocytes - T lymphocytes - B lymphocytes

  28. Platelets • Chips of cells, no nucleus • Smaller than RBC’s • Blood clotting

  29. The Lymphatic System • Some fluid (plasma) leaks out at capillaries & doesn’t return • Lymph system returns this fluid (now called lymph) to the circulatory system • Lymph nodes filter lymph and attack viruses & bacteria • System also functions in fat absorption • See diagram pg. 934

  30. The Body’s Defense

  31. Two Mechanisms • Nonspecific • Specific

  32. Nonspecific 1st line skin mucous membranes secretions like lysosyme

  33. Nonspecific cont’d - 2nd line a. phagocytic WBC’s (eat & use digestive enzymes) - 3 kinds 1. Neutrophils - attracted by chemicals (chemotaxis) - amoeboid movements - short life b/c self destruct

  34. Phagocytic WBC’s cont’d 2. Monocytes which become macrophages have long pseudopods & long life 3. Eosinophils – defend against lg. parasites like fluke

  35. 2nd line cont’d b. Natural Killer Cells - destroy bodies own cells that are infected by virus or may cause tumors - not phagocytic but cause lyseing

  36. 2nd line cont’d c. Inflammatory response pg. 935 - wounded cells release histamine - local vasodilation (capillaries dilate) causing more leaks - signals phagocytic WBC’s - more WBC’s to area (pus is dead phagocytes & fluids) - local temperature  - fever

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