Blood Pressure and Flow

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Blood Pressure and Flow
2011-02-24 10:10:10
Blood Pressure Flow

Blood Pressure and Flow
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  1. Typical Heart Rate
    • 60-80 bpm
    • AV node can't fire more than 230 bpm, so this is the highest possible frequency of ventricular contractions
  2. Bradycardia
    Heart rate is slower than normal
  3. Tachycardia
    Heart rate is faster than normal
  4. Electrocardiogram (EKG/ECG)
    • Recording of all action potentials in nodes and myocardial cells
    • Measured with electrodes on arms, legs, and sometimes chest
  5. P Wave
    SA node and atrial depolarization
  6. QRS Complex
    Ventricular depolarization
  7. ST Segment
    Ventricular Systole (plateau)
  8. T Wave
    Ventricular repolarization
  9. Nodal Rhythm
    • SA node not firing at all or not at the correct time
    • No P wave (or misplaced or inverted P Wave)
  10. Heart Block
    • Block anywhere in electrical conduction system
    • EKG signs depend on location of block
  11. Premature Ventricular Contraction
    Heartbeat initiated by ventricles instead of SA node
  12. Ventricular Tachycardia
    Four or more premature ventricular contractions without normal beats in between
  13. Ventricular Fibrillation
    Uncoordinated ventricular contractions
  14. Pressure
    Causes blood to flow
  15. Pressure Gradient
    • Pressure difference between two chambers
    • Fluid flows from high pressure to low pressure
  16. Cardiac Cycle Phases
    • 1. Ventricular Filling
    • 2. Isovolumetric Contraction
    • 3. Ventricular Ejection
    • 4. Isovolumetric Relaxation
  17. Ventricular Filling
    • Ventricles expand during diastole
    • Pressure drops below that of atria so blood rushes in
  18. 3 Phases of Ventricular Filling
    • Rapid ventricular filling: blood enters quickly
    • Diastasis: blood enters slowly
    • Astrial Systole: contraction
    • End-Diastolic Volume: amount of blood contained in each ventricle at end of filling (130 mL of blood)
  19. Isovolumetric Contraction
    • Ventricles depolarize (QRS complex)
    • Cardiocytes begin to contract, which increases pressure in ventricles
    • AV valves close
    • Isovolumetric because ventricles haven't yet ejected blood
    • Pressure is still high in aorta and pulmonary trunk
  20. Ventricular Ejection
    • Contraction of enough cardiocytes causes pressure in ventricle to exceed that of aorta/pulmonary trunk and semilunar valves to open
    • Rapid ejection at first
    • Reduced ejection follows
    • End Systolic Volume: Amount of blood left behind
  21. Stroke Volume
    • Amount of blood ejected
    • Normally about 70 mL
    • "Ejection Fraction": about 50% but much higher during vigorous exercise
  22. Isovolumetric Relaxation
    • Early phase of ventricular diastole
    • Ventricular expansion reduces pressure
    • Fluid in aorta/pulmonary trunk begins to flow backwards but this closes semilunar valves
  23. What does exercise do?
    • Primarily changes cardiac output: Amount ejected by each ventricle in one minute)
    • Cardiac Output: Heart rate x stroke volume
    • 4-6 L/min at rest
    • 21 L/min during vigorous exercise
    • Cardiac reserve: difference between maximum CO and resting CO
    • Increases with fitness
  24. How does exercise effect CO?
    • Proprioceptors signal cardiac center in medulla to increase sympathetic tone
    • Heart rate increase
    • Increase in volume of blood returning via veins, so increases ventricular pressure
    • SV increase
    • Increase SV allows heart to beat more slowly at rest
  25. Heart Sounds
    • "lub dub"
    • Lub: S1, loudest and longest sound; closure of AV valves
    • Dub: S2, softer and shorter sound; closure of semilunar valves
    • S3: normally only in youth and athletes; probably blood moving around between walls and vetricle
  26. Valvular Insufficiency
    Valve doesn't prevent reflux
  27. Valcular Stenosis
    • Cusps of valves are stiffened and opening constricted by scar tissue
    • Heart murmer
    • Sudden fainting or dizziness
  28. Mitral Regurgitation
    Mitral valve cusps bulge into atria during ventricular contraction