2/28/18. Cardiovascular System. Introduction. Anatomy. Chapter 26. Body is 60% to 80% fluid (by volume) Systems responsible for fluid movement are:

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1 Cardiovascular System Chapter 26 1 Introduction Body is 60% to 80% fluid (by volume) Systems responsible for fluid movement are: - Cardiovascular helps move fluid - Lymphatic Both called pick-up and delivery systems because main function is transportation 2 Anatomy Blood Blood vessels - Arteries - Veins - Capillaries Heart 3 1

2 Physiology Transportation - Moves gases, nutrients, wastes, and hormones Protection - White blood cells (WBCs) fight disease Combatting hemorrhage - Clotting mechanisms blood to prevent fluid loss from damaged vessels 4 Blood Blood color varies based on oxygen content; slightly warmer than normal body temperature Whole blood: 55% liquid, 45% blood cells Contains liquid plasma and formed elements such as: - Erythrocytes: Red blood cells (RBCs) - Leukocytes: WBCs - Thrombocytes: Platelets 5 Blood 8% of total body weight Volume in average-size person is: - 5 L (6 quarts or 12 pints) In adults, blood cells form in red bone marrow 6 2

3 Composition of Blood From Applegate E: The anatomy and physiology learning system, ed 4, St. Louis, 2011, Saunders. 7 Types of Blood Cells 8 Erythrocytes Transport oxygen and carbon dioxide Most numerous blood cell Characteristics include: - Bioconcave disks with flattened middles Lose nucleus and other organelles as they enter bloodstream RBCs are occupied by hemoglobin 9 3

4 Leukocytes Protect body from pathogens - Mobile army Removes dead cells and substances Life span: Ranges from a few hours to a few days, to several years 10 Leukocytes Types include: - Neutrophils - Eosinophils - Basophils - Monocytes - Lymphocytes Some WBCs produce histamines and antibodies 11 Thrombocytes Activate clotting and form platelet plugs - In contact with damaged vessels, they become larger and sticky to form platelet plugs Coagulation forms blood into a thick gel - Fibrin threads form network that traps RBCs, plasma, and fluid - Clot helps pull the injured vessel together Calcium and vitamin K needed for clotting 12 4

5 Fibrin Threads Copyright Dennis Kunkel Microscopy, Inc. 13 Plasma Straw-colored liquid Transports blood cells Constitutes 55% of blood volume - Plasma is 90% water and 10% solutes Fibrinogen functions in coagulation or blood clotting 14 Blood Classification Antigen: Inherited proteins on RBCs Types are: - Antigen A - Antigen B 15 5

6 Blood Classification Type A: Antigen A only Type B: Antigen B only Type AB: Both antigen A and antigen B Type O: Absence of antigen A and antigen B 16 Blood Classification Universal recipient: Type AB - Does not have reactive antibodies, so can receive all blood types Universal donor: Type O - Contains no antigens, compatible with other blood types 17 ABO Blood Types 18 6

7 Heart Hollow, muscular organ the size of a clenched fist Located in mediastinum: Space behind the sternum and between the lungs Pumping blood is main function - Four chambers: Two atria and two ventricles 19 Heart 20 Pericardium Double-layered sac surrounding heart - Parietal: Outer layer - Visceral: Inner layer Serous fluid located in pericardial space between layers - Helps reduce friction as heart beats 21 7

8 Heart Wall Epicardium - Contains fatty connective tissue and blood vessels or coronary vessels that nourish the heart Myocardium - Thick muscular layer - Contraction forces blood from chambers Endocardium - Inner lining, continuous with endothelial layer 22 Heart Wall Modified from Patton KT, Thibodeau GA: Anatomy & physiology, ed 7, St. Louis, 2010, Mosby. 23 Heart Chambers Atria - Superior chambers - Receive blood from large veins and pump it to inferior chambers Ventricles - Inferior chambers - Pump blood to organs and tissues 24 8

9 Heart Valves Flaps of endothelium between: - Heart chambers - Ventricles and some great vessels Function to: - Regulate blood flow through heart - Keep blood moving in one direction 25 Types of Valves Atrioventricular (AV) - Left AV valve: Bicuspid/mitral; right AV valve is tricuspid Semilunar (SL) - Aortic Left SL valve - Pulmonary Right SL valve 26 Atrioventricular Valves Tricuspid valve - Located between right atrium and right ventricle - Has three flaps (cusps) Bicuspid (mitral) valve - Located between left atrium and left ventricle - Has two flaps (cusps) 27 9

10 Semilunar Valves Aortic valve - Located between left ventricle and aorta Pulmonary valve - Located between pulmonary trunk and right ventricle 28 Heart Chambers and Valves Modified from Patton KT, Thibodeau GA: Anatomy & physiology, ed 7, St. Louis, 2010, Mosby. 29 Heart Sounds Produced as valves close Two characteristic sounds are lubb-dubb - Lubb: Low-pitched sound as AV valves close - Dubb: Higher-pitched sound as SL valves close 30 10

11 Cardiac Cycle Two ventricular phases - Diastole: Ventricles relax and fill with blood - Systole: Ventricles contract and eject blood Heart rate: Number of cardiac cycles that occur in 60 seconds - Tachycardia and bradycardia 31 Stage I Oxygen-depleted blood enters the heart and moves to: - Superior and inferior vena cava - Tricuspid valve - Right ventricle 32 Stage II Blood enters right ventricle and moves to: - Pulmonary trunk - Pulmonary arteries - Lungs - Pulmonary veins - Reoxygenated blood goes to left atrium 33 11

12 Stage III Blood enters the left atrium and moves to: - Left ventricle - Aorta - Many body cells 34 Heart's Conduction System SA node: - Generates heartbeat - Sets pace of heart rate SA node = pacemaker 35 Heart s Conduction System When SA node fires, atria contracts and ventricles fill with blood The signal then travels through bundle of His and Purkinje fibers Ventricles contract to eject blood into aorta and pulmonary trunk 36 12

13 Heart s Conduction System From Herlihy B: The human body in health and illness, ed 3, St. Louis, 2007, Saunders. 37 Blood Vessels Network of tubes connected to heart that transports blood Three main types: - Arteries: Move blood away from the heart - Veins: Return blood to the heart - Capillaries: Located between arterioles and venules Blood vessel wall layers - Tunica interna, tunica media, and tunica externa 38 Vascular Terms Lumen - Space between blood vessels Vasodilation - Occurs when lumen enlarges Vasoconstriction - Occurs when lumen becomes smaller 39 13

14 Vascular Terms Hyperemia - Increased local blood flow - Causes skin to redden and feel warm Ischemia - Decreased local blood flow - Causes skin to pale or become cool 40 Arteries Vessels moving blood away from heart Blood within arteries is oxygenated Walls are thicker and stronger (compared with veins) Arterioles: Smaller and thinner arteries 41 Pulse Expansion of arteries as blood leaves the heart Felt in arteries near body surface 42 14

15 Pulse Points From Herlihy B: The human body in health and illness, ed 3, St. Louis, 2007, Saunders. 43 Capillaries Located between arterioles and venules Functional unit of cardiovascular system Have thin, permeable walls Microcirculation: Blood flow to capillary beds Internal respiration: Gas exchange at capillary level 44 Veins Vessels moving blood toward heart Blood within veins is deoxygenated Compared to arteries, veins have: - Thinner walls that collapse easily - Wider lumens with less resistance to blood flow - Larger diameter as they reach the heart Venules: Smaller thinner veins 45 15

16 Blood Circulation From Herlihy B: The human body in health and illness, ed 3, St. Louis, 2007, Saunders. 46 Venous Return Venous return is like cardiac output Gravity helps blood return to the heart Mechanisms that assist blood flow are: - Venomotor tone - Skeletal muscle pump - Respiratory pump 47 Venomotor Tone Degree of muscle tone present in venous walls - Increase or decrease in tone may alter circulation Lack of tone may contribute to dizziness when sitting or standing up suddenly 48 16

17 Skeletal Muscle Pump Occurs during the squeeze-and-release action against vessel walls as skeletal muscles contract and relax - Promotes circulation of many body fluids Plays role in arterial and lymphatic circulation 49 Skeletal Muscle Pump From Herlihy B: The human body in health and illness, ed 3, St. Louis, 2007, Saunders. 50 Respiratory Pump Occurs as alternating compressive forces push against blood vessel walls - Caused by changes in thorax and abdomen during breathing During inhalation, the thoracic cavity enlarges mainly because diaphragm is descending Pressure gradient reverses during exhalation Venous blood moves upward toward heart 51 17

18 Respiratory Pump Modified from Patton KT, Thibodeau GA: Anatomy & physiology, ed 7, St. Louis, 2010, Mosby. 52 Major Arteries and Veins Names derived from: - Structures they lie over - Organs they serve Names change while passing through regions of the body - Example: Axillary becomes brachial artery Found on both sides - Identified as right and left 53 Major Arteries From Herlihy B: The human body in health and illness, ed 3, St. Louis, 2007, Saunders

19 Major Arteries and Veins Aorta Superior and inferior vena cava Brachiocephalic artery Subclavian artery and vein Common carotid artery Jugular veins (internal and external) 55 Major Arteries and Veins Axillary, brachial, ulnar, and radial arteries Femoral artery: Lies superficially just below the groin and then descends posteriorly through the adductor muscles Popliteal artery: Emerges from femoral artery Anterior and posterior tibial arteries: Divides into anterior and posterior arteries Dorsalis pedis artery Great saphenous vein 56 Branches of the Aorta From Herlihy B: The human body in health and illness, ed 3, St. Louis, 2007, Saunders

20 Major Veins From Herlihy B: The human body in health and illness, ed 3, St. Louis, 2007, Saunders. 58 Paths of Blood Circulation Two circuits (paths) of blood circulation based on areas they serve Types are: - Pulmonary - Systemic 59 Pulmonary Circuit Replenishes oxygen supply and eliminates gaseous wastes Path is: - From the right ventricle through the pulmonary arteries to the lungs, capillaries, and returns blood from the lungs through the pulmonary veins to the left atrium 60 20

21 Systemic Circuit Transports nutrients, hormones, and oxygen to body systems and carries wastes for elimination Path is: - Oxygenated blood moves from the left atrium to the left ventricle through arteries into the capillaries. - From here, deoxygenated blood moves from capillaries through veins and returns blood to the heart 61 Pulmonary and Systemic Circuits From Herlihy B: The human body in health and illness, ed 3, St. Louis, 2007, Saunders. 62 Portal Systems Occur when one capillary bed feeds into another capillary bed through a system of veins Functional significance: Blood can be directly transported to another area in high concentrations - Hepatic portal system - Hypophyseal portal system 63 21

22 Hepatic Portal System From Herlihy B: The human body in health and illness, ed 3, St. Louis, 2007, Saunders. 64 Blood Pressure Amount of pressure exerted by blood on vessel walls Systolic: Highest pressure - Occurs during ventricular contraction Diastole: Lowest pressure - Occurs when ventricles relax 65 Blood Pressure Sphygmomanometer: Used to measure blood pressure 120/80 mm Hg - Average blood pressure reading for healthy adult 140/90 mm Hg - Indicates high blood pressure or hypertension 66 22