CV Physiology Flashcards
Systemic circulation
path of oxygen rich blood from LV through aorta, pumped to all organ systems, back to heart (RA)
Pulmonary circulation
path of partially oxygen-depleted blood from RV through lungs and back to the heart (LA)
Semilunar valves
origin of pulmonary artery and aorta
one-way valves that open during systole to allow blood to enter pulmonary and systemic circulations
Atrioventricular valves
atria and ventricles are separated into 2 functional units by connective tissue and by AV valves
tricuspid and mitral valves
one-way valves that open during diastole to allow blood into ventricles
Valves…
prevent backflow of blood
what opens a valve is a difference in pressure
Cardiac Cycle
repeating pattern of contraction and relaxation of the heart
includes all mechanical and electrical events of the heart
divided into 5 phases
Systole
contraction phase
Diastole
relaxation phase
Phases of Cardiac Cycle
- atrial systole
- isovolumetric contraction
- ejection
- isovolumetric relaxation
- rapid inflow and diastasis
Phase 1 Cardiac Cycle
Atrial Systole
- Mitral valve is already open, ventricle has been filling with blood before atrial contraction
- P wave, atrial depolarization
- Atrial contraction pushes 10-20% more blood into ventricle
- S4 sound, always abnormal, vibration sound
Phase 2 Cardiac Cycle
Isovolumetric ventricular contraction
- QRS complex, ventricular depolarization
- contraction of ventricles causes ventricular pressure to rise
- S1 sound: LUB
- Ventricular P > atrial P, so AV valves closes
- EDV
Isovolumetric
- ventricles are not filling with blood because AV valves closed
- ventricles are not ejecting blood because ventricular pressure is less than aortic pressure, so semilunar valves are still closed
occurs during phase 2
End-diastolic volume
volume of blood in ventricle before ejection
about 120 mL
Phase 3 of Cardiac Cycle
Ejection
- Contraction of ventricles causes ventricular pressure to rise above aortic pressure
- Ventricular pressure > atrial pressure, AV valves are closed
- Ventricular repolarization (T wave)
- Stroke volume is about 80 mL
T wave
ventricular reploarization
LV pressure starts to fall
Stroke volume
volume of blood ejected during one contraction
resting SV = 80 mL
Phase 4 of Cardiac Cycle
Isovolumetric ventricular relaxation
- ventricles are fully repolarized and relaxed
- ventricular pressure falls below aortic pressure, AV closes
- S2 sound–DUB
- ESV–volume of blood in ventricles is constant
- phase lasts until pressure in ventricles falls to pressure in atria
Phase 5 Cardiac Cycle
Rapid inflow and diastasis
- ventricular pressure < atrial pressure, which opens AV valves
- ventricular pressure is low, chamber is relaxed
- Rapid ventricular filling occurs (S3 sounds)
- cycle returns to phase 1, with active rapid filling
longest phase of cardiac cycle
Diastasis
reduced ventricular filling and longest phase of cardiac cycle
S3 sound…
sometimes normal in <40 yrs
abnormal leads to heart failure