Cardiac Conduction System. (1) Conduction System of Heart Conduction System = Heart Beat & Pumping...
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Transcript of Cardiac Conduction System. (1) Conduction System of Heart Conduction System = Heart Beat & Pumping...
Cardiac Conduction
System
(1) Conduction System of Heart
• Conduction System = Heart Beat & Pumping
• Cardiac Contractions = Unconscious– Autonomic Nervous System decrease or
increase heart rate depending on circumstance
(2) Depolarization of the Heart
• Generate Action Potential & Depolarization:– Atria Ventricles
• Depolarization Path:1. SA Node AV Node
2. Atria Contract
3. (Delay) AV Bundle
4. Ventricles Contract
(Blood ejected out of arteries, leaving heart)
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter22/animation__conducting_system_of_the_heart.html
(3) Nodes & Bundles• Sinoatrial Node (SA Node)
– Right atrium– Starts each heart beat & sets rate– “Pacemaker”
• Atrioventricular Node (AV Node) = Left atrium
• AV Bundle = – Bundle Branches (along septum) – Purkinje Fibers (along entire muscular wall of heart)
(4) Cardiac Cycle• Diastole = Relax
– Blood passively filling atria
• Systole = Contract– Ventricles contract– Blood Ejected out of heart
(5) Diastole1. Ventricles relax
2. Semilunar valves closed
3. Ventricular Presure < Atrial Pressure– AV valves open– Ventricles fill with blood
4. Atria contract and force blood remaining in chambers into ventricles
(6) Systole1. Pressure increases in ventricles
- Filled with blood
2. AV valves close
3. Pressure in ventricles > Arteries leaving heart- Semilunar valves open- Blood rushes out of ventricles
4. Atria are relaxed and begin to fill back up
(7) Heart Beat• You hear something like “lub” “dup”
– “lub” = closing of AV valves• During ventricular systole
– “dup” = closing of semilunar valves• During early diastole
• You should NOT hear blood flow– You’ll hear it if flow is interrupted by blockage
http://www.csulb.edu/org/college/bme/respiratory_sounds/heart.wav
(8) Cardiac Output• Cardiac Output
– Amount of blood pumped out by each ventricle / 1 minute
– Cardiac Output = Heart Rate x Stroke Volume– CO = (HR)(SV)
• Stroke Volume– Volume of blood pumped out by ventricle – Increase of SV = Increase of ventricular force +
contraction
• Average Stroke Volume = 0.2L• Average Cardiac Output = 15L/min
(9) Starling’s Law• Starling’s Law of the Heart:
– Degree of cardiac muscle extension before contraction
– Increase Extension = Stronger Contraction– Degree of Extension result of percent filling of
ventricles