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The Heart (week 3) - Coggle Diagram

- - - - initiates electrical pulses that trigger the heartbeat, causing the atria to contract
  - - - receives electrical impulse from SA node and delays it slightly to allow ventricles to fill with blood before they contract
  - - - carry electrical impulses from AV node to right and left ventricles
      - ensure both ventricles contract simultaneously
- - - - heart is completely relaxed, semilunar valves are closed, AV valves are open
    - - atrial systole, semilunar valves are closed, AV valves are open
    - - ventricular systole, semilunar valves are closed, AV
        valves are closed
    - - Ventricular systole continues, semilunar valves are opened, AV valves are closed
    - - ventricular diastole, semilunar valves closed, AV valves closed
- - - - Parasympathetic stiumulation
        
        supplied by the vagus nerve
        
        decreases heart rate
        
        acetylcholine secreted and hyperpolarizes heart
      - Sympathetic stiumulation
        
        supplied by cardiac nerves
        
        innervate the SA and AV nodes, atrial and ventricular myocardium, and coronary vessels
        
        increases heart rate and force of contraction
        
        epinephrine and norepinephrine released
  - - - amount of stretch of the ventricular walls
      - Starling's law of the heart
        
        the greater the stretch, the greater the force of contraction
    - - pressure from contracting ventricles must produce to overcome the pressure in the aorta and move blood into the aorta
      - Clinical example:
        
        hypertension can lead to elevated afterload
        
        elevated afterload leads to increased resistance that the heart must overcome to pump blood out due to high blood pressure within arteries