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55 Cards in this Set
- Front
- Back
Cardiovascular system
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Heart and blood vessels
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Circulatory system
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Heart, blood vessels, and the blood
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Pulmonary circuit
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Carries blood to lungs for gas exchange and back to heart
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Systemic circuit
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Supplies oxygenated blood to all tissues of the body and returns it to the heart
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Pericardium
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double-walled sac (pericardial sac) that encloses the heart
Allows heart to beat without friction, provides room to expand, yet resists excessive expansion Anchored to diaphragm inferiorly and sternum anteriorly |
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Parietal pericardium
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—outer wall of sac
Superficial fibrous layer of connective tissue Deep, thin serous layer |
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Epicardium
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Visceral pericardium
heart covering Serous lining of sac turns inward at base of heart to cover the heart surface Adipose in thick layer in some places Coronary blood vessels travel through this layer |
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Pericardial cavity
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cavity—space inside the pericardial sac filled with 5 to 30 mL of pericardial fluid
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Endocardium
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Smooth inner lining of heart and blood vessels
Covers the valve surfaces and is continuous with endothelium of blood vessels |
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Myocardium
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Layer of cardiac muscle proportional to work load
Muscle spirals around heart which produces wringing motion |
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What are the four chambers?
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Right and left atria
Right and left ventricles |
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Interatrial septum
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Wall that separates atria
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Interventricular septum
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Muscular wall that separates ventricles
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How many valves and what are they?
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Pulmonary Semilunar
Aortic semilunar Tricuspid Bicuspid |
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Atrioventricular (AV) valves
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control blood flow between atria and ventricles
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Right AV valve
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has three cusps (tricuspid valve)
no oxygen |
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Left AV valve
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has two cusps (mitral or bicuspid valve)
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Chordae tendineae
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cords connect AV valves to papillary muscles on floor of ventricles
Prevent AV valves from flipping inside out or bulging into the atria when the ventricles contract |
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Semilunar valves
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control flow into great arteries; open and close because of blood flow and pressure
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Pulmonary semilunar valve
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in opening between right ventricle and pulmonary trunk
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Aortic semilunar valve
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in opening between left ventricle and aorta
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Myocardial infarction
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heart attack
Interruption of blood supply to the heart from a blood clot or fatty deposit (atheroma) can cause death of cardiac cells within minutes |
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Cardiocytes
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striated, short, thick, branched cells, one central nucleus surrounded by light-staining mass of glycogen
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Interdigitating folds
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folds interlock with each other, and increase surface area of contact
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Desmosomes
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weldlike mechanical junctions between cells
Prevents cardiocytes from being pulled apart |
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Gap junctions
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allow ions to flow between cells; can stimulate neighbors
Entire myocardium of either two atria or two ventricles acts like single, unified cell |
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The Conduction System
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Coordinates the heartbeat
Composed of an internal pacemaker and nervelike conduction pathways through myocardium |
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Sinoatrial (SA) node
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modified cardiocytes
Pacemaker initiates each heartbeat and determines heart rate Pacemaker in right atrium near base of superior vena cava Signals spread throughout atria |
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Atrioventricular (AV) node
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Located near the right AV valve at lower end of interatrial septum
Electrical gateway to the ventricles Fibrous skeleton—insulator prevents currents from getting to ventricles from any other route |
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Atrioventricular (AV) bundle (bundle of His)
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Bundle forks into right and left bundle branches
Branches pass through interventricular septum toward apex |
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Purkinje fibers
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Nervelike processes spread throughout ventricular myocardium
Signal passes from cell to cell through gap junctions |
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Sympathetic nerves
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Increase heart rate and contraction strength
Dilates coronary arteries to increase myocardial blood flow |
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Parasympathetic nerves
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Parasympathetic stimulation reduces the heart rate
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Systole
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atrial or ventricular contraction
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Diastole
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atrial or ventricular relaxation
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Sinus rhythm
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normal heartbeat triggered by the SA node
Set by SA node at 60 to 100 bpm Adult at rest is 70 to 80 bpm (vagal tone) |
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Nodal rhythm
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if SA node is damaged, heart rate is set by AV node, 40 to 50 bpm
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Intrinsic ventricular rhythm
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if both SA and AV nodes are not functioning, rate set at 20 to 40 bpm
Requires pacemaker to sustain life |
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Ectopic focus
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another part of heart fires before the SA node
Caused by hypoxia, electrolyte imbalance, or caffeine, nicotine, and other drugs |
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Arrhythmia
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any abnormal cardiac rhythm
Failure of conduction system to transmit signals (heart block) Bundle branch block Total heart block (damage to AV node) |
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P wave
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SA node fires, atria depolarize and contract
Atrial systole begins 100 ms after SA signal |
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QRS complex
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Ventricular depolarization
Complex shape of spike due to different thickness and shape of the two ventricles |
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T wave
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Ventricular repolarization and relaxation
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Pressure
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causes a fluid to flow (fluid dynamics)
Pressure gradient—pressure difference between two points Fluid flows down its pressure gradient from high pressure to low pressure |
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Resistance
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opposes fluid flow
Great vessels have positive blood pressure Ventricular pressure must rise above this resistance for blood to flow into great vessels |
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Auscultation
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listening to sounds made by body
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First heart sound (S1
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louder and longer “lubb,” occurs with closure of AV valves, turbulence in the bloodstream, and movements of the heart wall
occurs at the beginning of Isovolumetric contraction |
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Second heart sound (S2),
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softer and sharper “dupp,” occurs with closure of semilunar valves, turbulence in the bloodstream, and movements of the heart wall
occurs as blood rebounds from the closed semilunar valves and the ventricle expands...Isovolumetric relaxation |
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Phases of the Cardiac Cycle
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Ventricular filling
Isovolumetric contraction Ventricular ejection Isovolumetric relaxation All the events in the cardiac cycle are completed in less than 1 second! |
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Pulse
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surge of pressure produced by each heart beat that can be felt by palpating a superficial artery with the fingertips
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Tachycardia
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resting adult heart rate above 100 bpm
Stress, anxiety, drugs, heart disease, or fever Loss of blood or damage to myocardium |
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Bradycardia
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resting adult heart rate of less than 60 bpm
In sleep, low body temperature, and endurance-trained athletes |
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Preload
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the amount of tension in ventricular myocardium immediately before it begins to contract
Increased preload causes increased force of contraction |
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Frank–Starling law of the heart
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SV EDV
Stroke volume is proportional to the end diastolic volume Ventricles eject as much blood as they receive The more they are stretched, the harder they contract |
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Afterload
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blood pressure in the aorta and pulmonary trunk immediately distal to the semilunar valves
Opposes the opening of these valves Limits stroke volume |