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Is the central component of the cardiovascular system
Heart
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Propels blood through the blood vessels
Heart
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How many gallons of blood does the heart pump per year?
Over 1 million gallons
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Where is the heart located?
- In the mediastinum
- -area from the sternum to the vertebral column and between the lungs
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Hollow, cone-shaped organ abou the size of a closed fist
Heart
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How much of the heart lies to the left of the body's midline?
2/3
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-dense irregular CT
– protects and anchors the heart, prevents overstretchin
Pericardium
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– thin delicate membrane
– contains:
• parietal layer-outer layer
• pericardial cavity with pericardial fluid
• visceral layer (epicardium
Pericardium
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Layers of Heart Wall:
• Epicardium– visceral layer of serous pericardium
Epicardium
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Layers of Heart Wall:
– cardiac muscle layer is the bulk of the heart
Myocardium
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Layers of Heart Wall:
– chamber lining, consists of connective tissue covered with endothelium
Endocardium
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Whar are the 4 chambers of the heart?
- 2 upper atria
- 2 lower ventricles
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Right Atrium & Great Vessels:
What are the 3 sources of blood?
- 1. Superior vena cava
- 2. Inferior vena cava
- 3. Coronary sinus
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What partitions the right atrium?
Interatrial septum
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Right Atrium & Great Vessels:
– Blood flows into right ventricle
– has three cusps composed of dense CT covered by endocardium
Tricuspid valve (atrioventricular valve)
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Forms most of anterior surface of heart
Right ventricle
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Right ventricle:
What partitions ventricles?
Interventricular septum
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Right Ventricle:
Blood flows into pulmonary trunk, also known assemilunar valve (three cusps each shaped like half moon)
Pulmonary valve
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Forms most of the base of the heart• Receives blood from lungs - 4 pulmonary veins (2 right + 2 left)
Left Atrium
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Left Atrium:
Blood passes through into left ventricle– has two cusps (looks like Pope’s hat – Mitral valve)
Bicuspid valve
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Forms the apex of heart
Left Ventricle
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Left Ventricle:
– blood passes through valve into the ascending aorta
– just above valve are the openings to the coronary arteries
Aortic valve (semilunar valve)
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Thickness of __________ varies according to the function of the chamber
myocardium
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Myocardial Thickness and Function:
thin walled, deliver blood to adjacent ventricle
Atria
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Myocardial Thickness and Function:
Ventricle walls are much ________ and stronger
thicker
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Myocardial Thickness and Function:
Supplies blood to the lungs (little flow resistance)
Right ventricle
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Myocardial Thickness and Function:
wall is the thickest to supply systemic circulation
left ventricle wall
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Close preventing backflow of blood into atria
– occurs when ventricles contract, pushing valve cusps closed
A-V valves (Atrioventricular Valves)
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Open with ventricular contraction– allow blood to flow into pulmonary trunk and aorta
Semilunar Valves
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Valves that close with ventricular relaxation– prevents blood from returning to ventricles, blood fills valve cusps, tightly closing the valves
Semilunar valves
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What type of circuits are there for blood circulation?
Two closed circuits, the systemic and pulmonary
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– left side of heart pumps blood through body
– left ventricle pumps oxygenated blood into aorta
– aorta branches into many arteries that travel to organs
– arteries branch into many arterioles in tissue
– arterioles branch into thin-walled capillaries forexchange of gases and nutrients
– deoxygenated blood begins its return in venules
– venules merge into veins and return to right atrium
Systemic circulation
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– right side of heart pumps deoxygenated blood to lungs
– right ventricle pumps blood to pulmonary trunk
– pulmonary trunk branches into pulmonary arteries
– pulmonary arteries carry blood to lungs for exchange of gases
– oxygenated blood returns to heart in pulmonary veins
Pulmonary circulation
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Blood supply to the heart
Coronary circulation
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a very active muscle needs lots of O2
Heart
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Connections between arteries supplying blood to the same region, provide alternate routes if one arterybecomes occluded
Anastomoses
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• First branches off aorta
• Left coronary artery
• Right coronary artery
Coronary arteries
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Conduction System of Heart:
– cluster of cells in wall of Rt. Atria
– begins heart activity that spreads to both atria (contract simultaneously)
– contraction of all muscle fibers is assisted by presence of “intercalated discs” (gap junctions)
– excitation spreads to AV nod
Sinoatrial (SA) node
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Conduction System of Heart:
– Cells in wall (septum) between two atria adjacent to the ventricles
– Fires slower than SA node (allow for emptying of atria
Atrioventricular (AV) node
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Conduction System of Heart:
Signal travels from AV node along AV bundle (bundle of His) to the ventricle
AV Bundle (bundle of His)
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Conduction System of Heart:
Signal branches into the right and left bundle branches in the interventricular septum
Right and left bundle branches
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Conduction System of Heart
- conduct signals from bundle branches throughout the ventricular myocardium
Conduction myofibers (Purkinje fibers)
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– Action potentials of all active cells can be detected and recorded
EKG
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atrial depolarization
P wave
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Conduction time from atrial to ventricular excitation
P to Q interval
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Ventricular depolarization
QRS complex
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– ventricular repolarization
– atrial repolarization wave is hidden by QRS wave
T wave
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Stethoscope
Sounds of heartbeat are from turbulence in blood flow caused by valve closure
Auscultation
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– first heart sound (_____) is created with the closing of the atrioventricular valves
– second heart sound (_____) is created with the closing of semilunar valves
– contraction of heart chambers is called systole and relaxation is called diastol
lubb; dupp
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Regulation of Heart Rate:
Nervous control from the cardiovascular center in the ________
medulla
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Increases heart rate and force of contraction
Sympathetic impulses
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Impulses decrease heart rate
Parasympathetic impulses
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(pressure receptors, located in the arch of the aorta and carotid arteries) detect change in BP and send info to the cardiovascular center in the brain stem
Baroreceptors
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Affected by hormones
– epinephrine, norepinephrine, thyroid hormones
– ions (Na+, K+, Ca2+)
– age, gender, physical fitness, and temperature
Heart rate
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Heart muscle receiving insufficient blood supply
– narrowing of vessels---, artery spasm or clot
– smooth muscle & fatty deposits in walls of arteries
Treatment– drugs, bypass graft, angioplasty, stent
Coronary Artery Disease
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– death of area of heart muscle from lack of O2
– replaced with scar tissue
– results depend on size & location of damage
MI = myocardial infarction
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– use clot dissolving drugs streptokinase or t-PA & heparin
– balloon angioplast
Blood clot
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Heart pain from ischemia of cardiac muscle
Angina pectoris
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