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How much blood does the heart pump each minute throughout the body?
5 liters/min and our body has approx. 5-6 liters of blood
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Describe the heart and its location
- Cone shaped about the size of a first
- - Base is formed by atria and has broad posterior surface
- - Apex is formed by left ventricle and has a pointed tip
Located in mediastinum
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Where are the Base and Apex located?
Base: (?)
Apex: left side, resting on diaphragm
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Describe the Pericardium and its function
Membrane that surrounds & protects the heart
It confines heart to its location in mediastinum
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Describe the Fibrous Pericardium & its function
Superficial layer of Pericardium
It prevents overstretching of the heart by attaching to diaphragm & BV
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Describe the Serous Pericardium & its function
- 2 Layers:
- - Parietal: fused to fibrous pericardium
- - Visceral/Epicardium: adheres to surface of heart
- Pericardial Cavity: space between parietal & visceral
- Pericardial Fluid: slippy fluid that reduces friction during contraction
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What are the three layers of the heart?
- Epicardium
- Myocardium
- Endocardium
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What layer of the heart is the outermost layer?
Epicardium
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What layer is the thickest layer and describe its function?
Myocardium: middle layer of the heart that is responsible for contraction of the heart
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What layer does the Endocardium sit and what is its function?
Innermost layer, and it provides slippery surface that prevents friction as blood passes through within the chambers and valves
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Name the heart chamers (2)
Atria & Ventricles
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Which part of the heart chamber receives blood and describe its structure?
Atria: these are the upper heart chambers that contain auricles (pouch-like structures on anterior surface and slightly increases amount of blood it can hold)
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Which part of the heart chambers distribute blood & describe its structure?
Ventricles: these are the lower heart chambers
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What three veins carry blood to the Right Atrium?
- Superior Vena Cava
- Inferior Vena Cava
- Coronary Sinus
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What artery (from the Right Ventricle) is blood pumped?
Pulmonary Trunk
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Which veins carry blood from the lungs to the Left Atrium?
Pulmonary Veins
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Where does blood pass through from the Left Ventricle?
Aorta
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Describe the Sulci on the surface of the heart
- Sulci are grooves that contain BV & fat:
- - Coronary Sulcus: deep groove encircling heart, separating atria & ventricles
- - Anterior Interventricular Sulcus: shallow groove on anterior surface of heart separating R & L ventricles
- - Posterior Interventricular Sulcus: continues AIS on posterior surface and separates R & L ventricles
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What are the two heart valves?
Atrioventricular Valves & Semilunar Valves
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Describe the structure and function of the Atrioventricular Valves
Tricuspid Valve (R Atrioventricular): three cusps, located between R Atrium & R Ventricle
Bicuspid Valve (L Atrioventricular): two cusps, located between L Atrium & L Ventricle
Chordae Tendinae attaches cusps to papillary muscles
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Describe the structure & function of the Semilunar Valves
Pulmonary Semilunar Valve: between R Ventricle & Pulmonary Trunk
Aortic Semilunar Valve: between L Ventricle & Aorta
Semilunar Valves eject blood into Aorta
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Describe the blood pathway thru R heart
1. Inferior Vena Cava to Superior Vena Cava to Coronary Sinus into R atrium
- 2. Right Atrioventricular Valve into R Ventricle
- 3. Pulmonary Valve into Pulmonary Trunk
4. Enters Pulmonary Arteries
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Describe the blood pathway thru L heart
1. Pulmonary Veins into L Atrium
2. Left Atriventricular into L Ventricle
3. Aoric Valve into Aorta to body tissues
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Compare the thickness of the myocardium of each chamber
Thicker - L Ventricle
Thinner - R Ventricle
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How does thickness of myocardium relate to function of each chamber?
Thickness indicates amount of force it contracts - the thicker the muscle, the stronger the contraction
R Ventricle pumps blood into lungs, therefore its walls are thinner
L Ventricle pumps to the rest of the body, therefore its walls are thicker
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Define Stenosis
Narrowing of heart valve opening that decreases flow of blood
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Define Insufficiency
Failure of valve to close completely allowing backflow of blood
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How does Rheumatic Fever affect the heart?
It damages/destroys heart valves
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Describe the pathway of blood thru Pulmonary Circulation (Right Side of heart)
1. Oxygen-poor blood pumped from R Ventricle into Pulmonary Trunk
2. Pulmonary Arteries to lung- 3. Oxygen is added, Carbon Dioxide is removed
4. Pulmonary Veins to Left Atrium
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Describe the pathway of blood thru Systemic Circulation (Left Side of the heart)
1. Oxygen-rich blood pumped from Left Ventricle into Aorta
2. Systemic Arteries to different body areas
3. Enters Capillaries, loses Oxygen & gains Carbon Dioxide
4. Returns to Systemic Veins to Right Atrium
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What is the function of Coronary Circulation?
Supply blood to the heart wall
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What are some of the effects of blockage of coronary arteries?
- Myocardial Ischemia
- Hypoxia
- Myocardial Infarction
- Reperfusion
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What's the function of Autorhythmic Cells?
1. Spontaneously generates Action Potentials
2. Pacemakers
3. Form conduction system
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What are the components of the Conduction System?
1. Sinoatrial Node
2. Atrioventricular Node
3. Atrioventricular Bundle
4. Bundle Branches
5. Purkinje Fibers
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Describe the Sinoatrial (SA) Node of the Conduction System
- - Right atrial wall near superior vena cava
- - Unstable resting membrane potential- Action Potentials initiated by SA node spread to both atria via gap junctions
- - Spreads to AV Node
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Describe the Atrioventricular (AV) Node of the Conduction System
- - Interatrial Septum
- - Spreads to AV Bundle (bundle of His)
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Describe the Atrioventricular (AV) Bundle of the Conduction System
- - Conducts Action Potential from Atria to Ventricles
- - AV Bundles allow Action Potential to spread from atria to ventricles (because atria is electrically insulated from ventricles)
- - Spreads to Right & Left Bundle Branches
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Describe the Right & Left Bundle Branches of the Conduction System
- - Interventricular Septum
- - Propogated along bundle branches towards Apex- Enters Perkinje Fibers at Apex
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Describe the Perkinje Fibers of the Conduction System
- - Conduct Action Potential upwards to remainder of Ventricular Myocardium
- - Ventricles contract and blood is ejected to Semilunar Valves
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What is the pacemaker of the heart?
Sinoatrial Node (SA Node)
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Define Ectopic Pacemaker
Site other than SA Node is pacemaker due to damaged SA Node (Slow HR)
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What effect does the ANS have on the heart?
- Modifies Action Potentials the SA Node generates by:
- - Sympathetic: increases HR by increased Action Potential
- - Parasympathetic: decreases HR by decreased Action Potential
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Describe the stages of the Cardiac Muscle Cell Action Potential
1. Depolarization: opening of Voltage-Gated fast Na channels and Na enters cell
2. Plateau (Sustained Depolarization): opening of Voltage-Gated Ca channels and Ca enters cell
3. Repolarization: opening of Voltage-Gated K channels and K leaves cell
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Why is the Refractory Period length important in the cardiac muscle?
Tetanus can't occur in cardiac muscle fibers because Refractory Period lasts longer than the contraction itself
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What is ECG?
Electrocardiogram - a record currents generated by Action Potentials in the heart
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What are the components of a ECG?
- P Wave: atrial depolarization
- QRS Complex:
ventricular depolarization (atrial repolarization)
T Wave: ventricular repolarization
P-Q Interval: time between atrial action potential to ventricular action potential (elongated in heart block)
Q-T Interval: time between ventricular depolarization to ventricular repolarization (elongated in myocardial damage)
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Correlation of ECG and Atrial Systole
- - Follows P Wave
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Precedes ventricular systole, adding amount of blood to ventricles
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Correlation of ECG and Ventricular Systole
- - Follows QRS Complex (atrial diastole)
- - Dystole follows T Wave
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