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Circulatory system


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Circulatory system

  2. 2. The Heart 4 chambers Located between the lungs 2/3 of heart left of midline Apex points downward & contacts the diaphragm It lies in the pericardial cavity
  3. 3. The Heart It is separated from the other organs by a double- layered membrane = Pericardium The Pericardium is composed of a Fibrous Pericardium & a Serous Pericardium. The serous pericardium has 2 parts:  1. Parietal layer - attached to the back of the fibrous pericardium  2. Visceral layer (epicardium) - attached to the heart muscle  These two are separated by a fluid filled space = pericardial cavity.
  4. 4. The Heart Wall A. Epicardium - outermost, = Visceral layer of the serous pericardium
  5. 5. Heart Wall B. Myocardium - middle, = Cardiac muscle cells (very thick)
  6. 6. The Heart Wall C. Endocardium - innermost, forms valves, & is continuous with the endothelium of the blood vessels that enter & leave the heart
  7. 7. Chambers 4 chambers  2 upper: Lt. & Rt. Atrium  2 lower: Lt. & Rt. Ventricle
  8. 8. Valves 4 valves  2 Atrioventricular (AV) Valves  Rt. AV valve = tricuspid  Lt. AV valve = bicuspid, mitral  2 semilunar valves: found at the base of 2 large vessels leaving the heart = Pulmonary & Aortic valves
  9. 9. Blood flow
  10. 10. Blood Flow 1. Rt. Atrium: receives deoxygenated (venous) blood from 3 vessels;  A. Superior vena cava - blood from above the heart  B. Inferior vena cava - blood from below the heart  C. Coronary sinus - blood from the heart muscle
  11. 11. Blood Flow 2. Blood flows through Rt. AV valve into Rt. Ventricle (the flaps of AV valves are held in place by Chordae Tendineae & Papillary Muscles to prevent back flow)
  12. 12. Blood Flow 3. Rt. Ventricle contracts & blood exits through the Pulmonary Semilunar valve. It enters the Pulmonary trunk which divides into Lt. & Rt. Pulmonary arteries. Blood goes to lungs (carbon dioxide out, oxygen in)
  13. 13. Blood Flow cont. 4. Oxygenated blood returns from the lungs through the Pulmonary veins to the Lt. Atrium
  14. 14. Blood Flow 5. Blood flows through the Lt. AV valve (bicuspid, mitral) to the Lt. Ventricle
  15. 15. Blood Flow 6. Lt. Ventricle contracts & blood exits through the Aortic Semilunar valve & enters Ascending Aorta.
  16. 16. Coronary circulation (Blood flow to HeartMuscle) First vessels off of the Ascending Aorta = Lt. & Rt. Coronary Arteries
  17. 17. Coronary Circulation cont. The blood returns from the heart muscle via 2 major veins  1. Great Cardiac vein: brings deoxygenated blood back from the anterior heart wall  2. Middle Cardiac vein: brings deoxygenated blood back from the posterior heart wall. Both vessels empty into the Coronary Sinus (a large vein on back of heart). It empties into Rt. Atrium
  18. 18. Conduction system An electrical system. It determines the rate & rhythm of the heartbeat 1. Sinoatrial node (SA node, pacemaker) - Neurons fire at 70/80 beats per minute, causes atria to contract 2. Atrioventricular node (AV node) - neurons fire at 40-50 beats per minute; typically the SA node overrides it, but if SA node is not functioning it will ultimately cause ventricles to contract at a slower rate.
  19. 19. Conduction System 3. Atrioventricular Bundle (Bundle of His) - conducts impulses between ventricles 4. The AV Bundle divides into lt & rt Bundle Branches which go to the ventricles. 5. Purkinje fibers - deliver impulses directly to the myocardium of the ventricles.
  20. 20. Blood – connective tissue with fluidmatrix A. Fluid = plasma B. Blood cells = formed elements  1. Red blood cells (RBCs) = ERYTHROCYTES  a. Flattened, biconcave, anucleated discs  b. Life span - 120 days  c. Function: transport oxygen & carbon dioxide bound pigmented protein = hemoglobin
  21. 21. Blood cont. 2. White blood cells (WBCs) = LEUKOCYTES  a.granulocytes  i. eosinophils  ii. Basophils  iii. Neutrophils
  22. 22. Blood cont. 2. White blood cells (WBCs) = LEUKOCYTES  b. Agranulocytes  i. Monocytes  ii. Lymphocytes
  23. 23. Blood cont. 3. Thrombocytes = PLATELETS; not cells. Cytoplasmic fragments of megakaryocytes. Assists in blood clot formation.
  24. 24. Hemopoiesis = Blood Cell formation.Occurs in red bone marrow. A. Erythropoiesis = RBC formation B. Leukopoiesis = WBC formation C. Thrombopoiesis = platelet formation
  25. 25. Blood vessels: blood flowBlood flows from the heart through progressively narrowing vessels; artery ->arteriole -> capillaryAnd returns through progressively enlarging vessels; venules -> vein-> heart
  26. 26. Blood vessels Structure: arteries and veins have 3 tunics  1. Tunica Externa (adventitia) - Outermost, loose connective tissue, this is the thickest layer in veins  2. Tunica Media - middle, smooth muscle layer, this is the thickest layer in arteries  3. Tunica Intima - innermost  a. Endothelium - simple squamous + c.t.  b. Subendothelial layer - c.t.
  27. 27. Arteries (carry blood away from heart) Elastic - large amount of elastin expandable Muscular - tunica media is predominantly smooth muscle. There is an elastic lamina on each face of the tunica media
  28. 28. Arterioles - Smallest, tunica media very thin (<10 layers)
  29. 29. Capillaries "Functional units" of circulatory system, very thin-walled, allows for exchange of gases, nutrients, & waste products. Composed of the Tunica Intima only
  30. 30. Venules   Usually lack a tunica media. They have the other two tunics
  31. 31. Veins Carry blood to the heart) All 3 tunics present. Veins have a very Low pressure, The blood flow through them is dependent on:  A. Contraction of surrounding musculature = Skeletal muscle "pump"  B. One-way valves