1 / 92

Chapter 13

Chapter 13. Heart and Circulation. 13-1. Chapter 13 Outline Overview Blood Pulmonary & Systemic Circulations Heart Valves Cardiac Cycle Electrical Activity of the Heart Structure of Blood Vessels Heart Disease Lymphatic System . 13-2. Overview . 13-3.

summer
Download Presentation

Chapter 13

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 13 Heart and Circulation 13-1

  2. Chapter 13 Outline • Overview • Blood • Pulmonary & Systemic Circulations • Heart Valves • Cardiac Cycle • Electrical Activity of the Heart • Structure of Blood Vessels • Heart Disease • Lymphatic System 13-2

  3. Overview 13-3

  4. Functions of Circulatory System • Include transportation of respiratory gases, delivery of nutrients & hormones, & waste removal • Include roles in temperature regulation, clotting, & immune function 13-4

  5. Components of Circulatory System • Include cardiovascular & lymphaticsystems • Heart pumps blood thru cardiovascular system • Blood vessels carry blood from heart to cells & back • Includes arteries, arterioles, capillaries, venules, veins • Lymphatic system picks up excess fluid filtered out in capillary beds & returns it to veins • Its lymph nodes are part of immune system 13-5

  6. Blood 13-6

  7. Composition of Blood • Consists of formed elements (cells) suspended & carried in plasma (fluid part) • Total blood volume is about 5L • Plasma is straw-colored liquid consisting of H20 & dissolved solutes • Includes ions, metabolites, hormones, antibodies 13-7

  8. Plasma Proteins • Constitute 7-9% of plasma • Three types of plasma proteins: albumins, globulins, & fibrinogen • Albumin accounts for 60-80% • Creates colloid osmotic pressure that draws H20 from interstitial fluid into capillaries to maintain blood volume & pressure • Globulins carry lipids • Gamma globulins are antibodies • Fibrinogen serves as clotting factor • Converted to fibrin • Serum is fluid left when blood clots 13-8

  9. Formed Elements Fig 13.3 • Are erythrocytes (RBCs) & leukocytes (WBCs) • RBCs are flattened biconcave discs • Shape provides increased surface area for diffusion • Lack nuclei & mitochondria • Each RBC contains 280 million hemoglobins 13-9

  10. Leukocytes • Have nucleus, mitochondria, & amoeboid ability • Can squeeze through capillary walls (diapedesis) • Granular leukocytes help detoxify foreign substances & release heparin • Include eosinophils, basophils, & neutrophils Fig 13.3 13-10

  11. Leukocytes continued • Agranular leukocytes are phagocytic & produce antibodies • Include lymphocytes & monocytes Fig 13.3 13-11

  12. Platelets (thrombocytes) • Are smallest of formed elements, lack nucleus • Are fragments of megakaryocytes; amoeboid • Constitute most of mass of blood clots • Release serotonin to vasoconstrict & reduce blood flow to clot area • Secrete growth factors to maintain integrity of blood vessel wall • Survive 5-9 days Fig 13.3 13-12

  13. Hematopoiesis • Is formation of blood cells from stem cells in marrow (myeloid tissue) & lymphoid tissue • Erythropoiesis is formation of RBCs • Stimulated by erythropoietin (EPO) from kidney • Leukopoiesis is formation of WBCs • Stimulated by variety of cytokines • = autocrine regulators secreted by immune system 13-13

  14. Erythropoiesis • 2.5 million RBCs are produced/sec • Lifespan of 120 days • Old RBCs removed from blood by phagocytic cells in liver, spleen, & bone marrow • Iron recycled back into hemoglobin production Fig 13.4 13-14

  15. RBC Antigens & Blood Typing • Antigens present on RBC surface specify blood type • Major antigen group is ABOsystem • Type A blood has only A antigens • Type B has only B antigens • Type AB has both A & B antigens • Type O has neither A or B antigens 13-15

  16. Transfusion Reactions • People with Type A blood make antibodies to Type B RBCs, but not to Type A • Type B blood has antibodies to Type A RBCs but not to Type B • Type AB blood doesn’t have antibodies to A or B • Type O has antibodies to both Type A & B • If different blood types are mixed, antibodies will cause mixture to agglutinate Fig 13.5 13-16

  17. Transfusion Reactions continued • If blood types don't match, recipient’s antibodies agglutinate donor’s RBCs • Type O is “universal donor” because lacks A & B antigens • Recipient’s antibodies won’t agglutinate donor’s Type O RBCs • Type AB is “universal recipient” because doesn’t make anti-A or anti-B antibodies • Won’t agglutinate donor’s RBCs • Insert fig. 13.6 Fig 13.6 13-17

  18. Rh Factor • Is another type of antigen found on RBCs • Rh+ has Rho(D) antigens; Rh- does not • Can cause problems when Rh- mother has Rh+ babies • At birth, mother may be exposed to Rh+ blood of fetus • In later pregnancies mom may produce Rh antibodies • In Erythroblastosis fetalis, this happens & antibodies cross placenta causing hemolysis of fetal RBCs 13-18

  19. Hemostasis • Is cessation of bleeding • Promoted by reactions initiated by vessel injury: • Vasoconstriction restricts blood flow to area • Platelet plug forms • Plug & surroundings are infiltrated by web of fibrin, forming clot 13-19

  20. Role of Platelets • Platelets don't stick to intact endothelium because of presence of prostacyclin (PGI2--a prostaglandin) & NO • Keep clots from forming & are vasodilators Fig 13.7a 13-20

  21. Role of Platelets • Damage to endothelium allows platelets to bind to exposed collagen • von Willebrand factor increases bond by binding to both collagen & platelets • Platelets stick to collagen & release ADP, serotonin, & thromboxane A2 • = platelet release reaction Fig 13.7b 13-21

  22. Role of Platelets continued • Serotonin & thromboxane A2 stimulate vasoconstriction, reducing blood flow to wound • ADP & thromboxane A2 cause other platelets to become sticky & attach & undergo platelet release reaction • This continues until platelet plug is formed Fig 13.7c 13-22

  23. Role of Fibrin • Platelet plug becomes infiltrated by meshwork of fibrin • Clot now contains platelets, fibrin & trapped RBCs • Platelet plug undergoes plug contraction to form more compact plug 13-23

  24. Conversion of Fibrinogen to Fibrin • Can occur via 2 pathways: • Intrinsic pathway clots damaged vessels & blood left in test tube • Initiated by exposure of blood to negatively charged surface of glass or blood vessel collagen • This activates factor XII (a protease) which initiates a series of clotting factors • Ca2+ & phospholipids convert prothrombin to thrombin • Thrombin converts fibrinogen to fibrin which polymerizes to form a mesh • Damage outside blood vessels releases tissuethromboplastin that triggers a clotting shortcut (= extrinsic pathway) 13-24

  25. Fig 13.9 13-25

  26. Dissolution of Clots • When damage is repaired, activated factor XII causes activation of kallikrein • Kallikrein converts plasminogen to plasmin • Plasmin digests fibrin, dissolving clot 13-26

  27. Anticoagulants • Clotting can be prevented by Ca+2 chelators (e.g. sodium citrate or EDTA) • or heparin which activates antithrombin III (blocks thrombin) • Coumarin blocks clotting by inhibiting activation of Vit K • Vit K works indirectly by reducing Ca+2 availability 13-27

  28. Pulmonary & Systemic Circulations 13-28

  29. Structure of Heart • Heart has 4 chambers • 2 atria receive blood from venous system • 2 ventricles pump blood to arteries • 2 sides of heart are 2 pumps separated by muscular septum Fig 13.10 13-29

  30. Structure of Heart continued • Between atria & ventricles is layer of dense connective tissue called fibrous skeleton • Which structurally & functionally separates the two • Myocardial cells of atria attach to top of fibrous skeleton & form 1 unit (or myocardium) • Cells from ventricles attach to bottom & form another unit • Fibrous skeleton also forms rings, the annuli fibrosi, to hold heart valves 13-30

  31. Pulmonary & Systemic Circulations • Blood coming from tissues enters superior & inferior vena cavae which empties into right atrium, then goes to right ventricle which pumps it through pulmonary arteries to lungs Fig 13.10 13-31

  32. Pulmonary & Systemic Circulations continued • Oygenated blood from lungs passes thru pulmonary veins to left atrium, then to left ventricle which pumps it through aorta to body Fig 13.10 13-32

  33. Pulmonary & Systemic Circulations continued • Pulmonary circulation is path of blood from right ventricle through lungs & back to heart • Systemic circulation is path of blood from left ventricle to body & back to heart • Rate of flow through systemic circulation = flow rate thru pulmonary circuit Fig 13.10 13-33

  34. Pulmonary & Systemic Circulations continued • Resistance in systemic circuit > pulmonary • Amount of work done by left ventricle pumping to systemic is 5-7X greater • Causing left ventricle to be more muscular (3-4X thicker) Fig 13.11 13-34

  35. Heart Valves 13-35

  36. Atrioventricular Valves • Blood flows from atria into ventricles thru 1-way atrioventricular (AV) valves • Between right atrium & ventricular is tricuspid valve • Between left atrium & ventricular is bicuspid or mitral valve Fig 13.11 13-36

  37. Atrioventricular Valves continued • Opening & closing of valves results from pressure differences • High pressure of ventricular contraction is prevented from everting AV valves by contraction of papillary muscles which are connected to AVs by chorda tendinea 13-37

  38. Semilunar Valves • During ventricular contraction blood is pumped through aortic & pulmonary semilunar valves • Close during relaxation Fig 13.11 13-38

  39. Cardiac Cycle 13-39

  40. Cardiac Cycle • Is repeating pattern of contraction & relaxation of heart • Systole refers to contraction phase • Diastole refers to relaxation phase • Both atria contract simultaneously; ventricles follow 0.1-0.2 sec later 13-40

  41. Cardiac Cycle • End-diastolic volume is volume of blood in ventricles at end of diastole • Stroke volume is amount of blood ejected from ventricles during systole • End-systolic volume is amount of blood left in ventricles at end of systole 13-41

  42. Cardiac Cycle continued • As ventricles begin contraction, pressure rises closing AV valves • Called isovolumetric contraction because all valves are closed • When pressure in ventricles exceeds that in aorta, semilunar valves open & ejection begins • As pressure in ventricle falls below that in aorta, back pressure closes semilunars • All valves are closed & ventricles undergo isovolumetricrelaxation • When pressure in ventricles falls below atria, AVs open & ventricles fill • Atrial systole sends its blood into ventricles 13-42

  43. Fig 13.14 13-43

  44. Heart Sounds • Closing of AV & semilunar valves produces sounds that can be heard thru stethoscope • Lub (1st sound) produced by closing of AV valves • Dup (2nd sound) produced by closing of semilunars 13-44

  45. Heart Murmurs • Are abnormal sounds produced by abnormal patterns of blood flow in heart • Many caused by defective heart valves • Can be of congenital origin • In rheumatic fever, damage can be from antibodies made in response to strep infection 13-45

  46. Heart Murmurs continued • In mitral stenosis, mitral valve becomes thickened & calcified, impairing blood flow from left atrium to left ventricle • Accumulation of blood in left ventricle can cause pulmonary hypertension • Valves are incompetent when don't close properly • Can be from damage to papillary muscles 13-46

  47. Heart Murmurs continued • Mumurs caused by septal defects are usually congenital • Due to holes in septum between left & right sides of heart • Pressure causes blood to pass from left to right Fig 13.16 13-47

  48. Electrical Activity of Heart 13-48

  49. Electrical Activity of Heart • Myocardial cells are short, branched, & interconnected by gap junctions • Entire muscle that forms a chamber is called a myocardium or functional syncitium • Because APs originating in any cell are transmitted to all others • Chambers separated by nonconductive tissue 13-49

  50. SA Node Pacemaker • In normal heart, SA node functions as pacemaker • Depolarizes spontaneously to threshold (= pacemaker potential) Fig 13.20 13-50

More Related