1. Chapter 13 Heart and Circulation
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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
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3. Overview
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4. Functions of Circulatory System
Include transportation of respiratory gases, delivery of nutrients & hormones, & waste removal.
Provides regulation via hormones.
Include roles in temperature regulation, clotting, & immune function.
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5. Components of Circulatory System
Include cardiovascular & lymphatic systems
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
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6. Blood
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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
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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
Alpha, Beta, & Gamma globulins antibodies
Fibrinogen serves as clotting factor
Converted to fibrin
Serum is fluid left when blood clots
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9. Formed Elements Are erythrocytes (RBCs) & leukocytes (WBCs)
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
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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
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11. Leukocytes continued
Agranular leukocytes are phagocytic & produce antibodies
Include lymphocytes & monocytes
Fig 13.3
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12. WBC Never Let Monkey Eat Bananas
All WBCs (leukocytes) have a nucleus and no hemoglobin
Granular or agranular classification based on presence of cytoplasmic granules made visible by staining
granulocytes are neutrophils, eosinophils or basophils
agranulocytes are monocyes or lymphocytes

13. 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
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14. 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
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15. Erythropoiesis 2.5 million RBCs are produced/sec
A normal red blood cell count is in the range of million /mm3.
Lifespan of 120 days
Old RBCs removed from blood by phagocytic cells in liver, spleen, & bone marrow
Iron recycled
Fig 13.4
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16. RBC Antigens & Blood Typing
Antigens present on RBC surface specify blood type
Major antigen group is ABO system
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
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17. 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
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18. 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
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19. 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
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20. 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
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21. 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
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22. 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
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23. Polycythemia= increased RBCs
Polycythemia would be induced by decreased oxygen in the blood

24. Pulmonary & Systemic Circulations
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25. 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
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26. 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
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27. 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
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28. 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
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29. 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
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30. 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
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31. Heart Valves
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32. 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
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33. 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
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34. Semilunar Valves
During ventricular contraction blood is pumped through aortic & pulmonary semilunar valves
Close during relaxation
Fig 13.11
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35. Cardiac Cycle
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36. 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 sec later
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37. 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
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38. Heart Sounds
Closing of AV & semilunar valves produces sounds that can be heard thru stethoscope
Lub (1st sound) produced by closing of AV valves
Dub (2nd sound) produced by closing of semilunars
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39. 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
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40. 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
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41. 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
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42. Electrical Activity of Heart
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43. 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
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44. SA Node Pacemaker In normal heart, SA node functions as pacemaker
Depolarizes spontaneously to threshold (= pacemaker potential)
Fig 13.20
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45. Ectopic Pacemakers Other tissues in heart are spontaneously active
But are slower than SA node
Are stimulated to produce APs by SA node before spontaneously depolarize to threshold
If APs from SA node are prevented from reaching these, they will generate pacemaker potentials
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46. Myocardial APs Myocardial cells have RMP of -85 to –90 mV
Depolarized to threshold by APs originating in SA node
Unlike the AP of other cells, this level of depolarization is maintained for msec before repolarization, resulting from the slow indward diffusion of Ca2+ through slow Ca2+ channels.
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47. Conducting Tissues of Heart
Fig 13.20
APs from SA node spread through atrial myocardium via gap junctions
But need special pathway to ventricles because of non-conducting fibrous tissue
AV node at base of right atrium & bundle of His/AV bundle conduct APs to ventricles
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48. Conducting Tissues of Heart continued
Fig 13.20
In septum of ventricles, His divides into right & left bundle branches
Which give rise to Purkinje fibers in walls of ventricles
These stimulate contraction of ventricles
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49. Conduction of APs APs from SA node spread at rate of 0.8 -1 m/sec
Time delay occurs as APs pass through AV node
Has slow conduction of 0.03– 0.05 m/sec
AP speed increases in Purkinje fibers to 5 m/sec
Ventricular contraction begins 0.1–0.2 sec after contraction of atria
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50. Electrocardiogram (ECG/EKG)
Is a recording of electrical activity of heart conducted thru ions in body to surface
Fig 13.22a
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51. ECG 3 distinct waves are produced during cardiac cycle
P wave caused by atrial depolarization
QRS complex caused by ventricular depolarization
T wave results from ventricular repolarization
Fig 13.24
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52. Correlation of ECG with Heart Sounds
1st heart sound (lub) comes immediately after QRS wave as AV valves close
2nd heart sound (dub) comes as T wave begins & semilunar valves close.
Fig 13.25
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53. Structure of Blood Vessels
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54. Structure of Blood Vessels
Innermost layer of all vessels is the endothelium
Capillaries are made of only endothelial cells
Arteries & veins have 3 layers called tunica externa, media, & interna/intima
Externa is connective tissue
Media is mostly smooth muscle
Interna is made of endothelium, basement membrane, & elastin
Although have same basic elements, arteries & veins are quite different
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55. Arteries Large arteries are muscular & elastic Contain lots of elastin
Expand during systole & recoil during diastole
Helps maintain smooth blood flow during diastole
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56. Arteries Small arteries & arterioles are muscular
Provide most resistance in circulatory system
Arterioles cause greatest pressure drop
Mostly connect to capillary beds
Some connect directly to veins to form arteriovenous anastomoses
Fig 13.27
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57. Capillaries Provide extensive surface area for exchange
Blood flow through a capillary bed is determined by state of precapillary spincters of arteriole supplying it
Fig 13.27
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58. Types of Capillaries
Continuous capillaries, endothelial cells are tightly joined together
Have narrow intercellular channels that permit exchange of molecules smaller than proteins
Present in muscle, lungs, adipose tissue
Fenestrated capillaries have wide intercellular pores
Very permeable
Present in kidneys, endocrine glands, intestines.
Discontinuous capillaries have large gaps in endothelium
Are large & leaky
Present in liver, spleen, bone marrow.
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59. Veins Contain majority of blood in circulatory system
Very compliant (expand readily)
Contain very low pressure (about 2mm Hg)
Insufficient to return blood to heart
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60. Veins
Fig 13.30
Blood is moved toward heart by contraction of surrounding skeletal muscles (skeletal muscle pump)
& pressure drops in chest during breathing
1-way venous valves ensure blood moves only toward heart
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61. Heart Disease
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62. Atherosclerosis
Is most common form of arteriosclerosis (hardening of arteries)
Accounts for 50% of deaths in US
Localized plaques (atheromas) reduce flow in an artery
& act as sites for thrombus (blood clots)
Fig 13.32
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63. Atherosclerosis Plaques begin at sites of damage to endothelium
E.g. from hypertension, smoking, high cholesterol, or diabetes
Fig 13.32b
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64. Cholesterol & Plasma Lipoproteins
High blood cholesterol is associated with risk of atherosclerosis
Lipids, including cholesterol, are carried in blood attached to LDLs (low-density lipoproteins) & HDLs (high-density lipoproteins)
Fig 13.33
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65. Cholesterol & Plasma Lipoproteins
LDLs & HDLs are produced in liver & taken into cells by receptor-mediated endocytosis
In cells LDL is oxidized
Oxidized LDL can injure endothelial cells facilitating plaque formation
Arteries have receptors for LDL but not HDL
Which is why HDL isn't atherosclerotic
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66. Ischemic Heart Disease
Is most commonly due to atherosclerosis in coronary arteries
Ischemia occurs when blood supply to tissue is deficient
Causes increased lactic acid from anaerobic metabolism
Often accompanied by angina pectoris (chest pain)
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67. Ischemic Heart Disease
Detectable by changes in S-T segment of ECG
Myocardial infarction (MI) is a heart attack
Diagnosed by high levels of creatine phosphate (CPK) & lactate dehydrogenase (LDH)
Fig 13.34
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68. Arrhythmias Detected on ECG
Arrhythmias are abnormal heart rhythms
Heart rate <60/min is bradycardia; >100/min is tachycardia Arrhythmias animation
Fig 13.35
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69. Arrhythmias Detected on ECG continued
In flutter contraction rates can be /min
In fibrillation contraction of myocardial cells is uncoordinated & pumping ineffective
Ventricular fibrillation is life-threatening
Electrical defibrillation resynchronizes heart by depolarizing all cells at same time
Arrhythmias ablation animation
Fig 13.35
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70. Arrhythmias Detected on ECG continued
AV node block occur when node is damaged
First–degree AV node block is when conduction through AV node > 0.2 sec
Causes long P-R interval
Second-degree AV node block is when only 1 out of 2-4 atrial APs can pass to ventricles
Causes P waves with no QRS
In third-degree or complete AV node block no atrial activity passes to ventricles
Ventricles driven slowly by bundle of His or Purkinjes
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71. Arrhythmias Detected on ECG continued
AV node block occurs when node is damaged
First–degree AV node block is when conduction thru AV node > 0.2 sec
Causes long P-R interval
Fig 13.36
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72. Arrhythmias Detected on ECG continued
Second-degree AV node block is when only 1 out of 2-4 atrial APs can pass to ventricles
Causes P waves with no QRS
Fig 13.36
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73. Arrhythmias Detected on ECG continued
In third-degree or complete AV node block, no atrial activity passes to ventricles
Ventricles are driven slowly by bundle of His or Purkinjes
Fig 13.36
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74. Lymphatic System
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75. Lymphatic System Has 3 basic functions:
Transports interstitial fluid (lymph) back to blood
Transports absorbed fat from small intestine to blood
Helps provide immunological defenses against pathogens
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76. Lymphatic System continued
Lymphatic capillaries are closed-end tubes that form vast networks in intercellular spaces
Very porous, absorb proteins, microorganisms, fat
Fig 13.37
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77. Lymphatic System continued
Lymph is carried from lymph capillaries to lymph ducts to lymph nodes
Fig 13.38
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78. Lymphatic System continued
Lymph nodes filter lymph before returning it to veins via thoracic duct or right lymphatic duct
Nodes make lymphocytes & contain phagocytic cells that remove pathogens
Lymphocytes also made in tonsils, spleen, thymus
Fig 13.39
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