1. Cardiac muscle and cardiac cycle
2. ECG, conduction system, and arrhythmia basics
3. Hemodynamics, pressure-flow relationships, and vascular resistance
4. Arterial pressure and its regulation
5. Venous return, cardiac output, and shock
6. Microcirculation, capillary exchange, and edema
7. Regional circulation: coronary, cerebral, renal, skeletal muscle, skin
8. Exercise and cardiovascular reflexes

1. Cardiac muscle and cardiac cycle
2. ECG, conduction system, and arrhythmia basics
3. Hemodynamics, pressure-flow relationships, and vascular resistance
4. Arterial pressure and its regulation
5. Venous return, cardiac output, and shock
6. Microcirculation, capillary exchange, and edema
7. Regional circulation: coronary, cerebral, renal, skeletal muscle, skin
8. Exercise and cardiovascular reflexes

1. Cardiac cycle
2. ECG and cardiac conduction
3. Cardiac output and venous return
4. Blood pressure regulation
5. Microcirculation and edema
6. Regional circulation
7. Full CVS physiology exam outline

Cardiac cycle: step-by-step

• Mitral valve: left atrium to left ventricle
• Aortic valve: left ventricle to aorta

1. Atrial systole

• ECG: follows the P wave, which represents atrial depolarization.
• The atria contract and push the final amount of blood into relaxed ventricles.
• Mitral valve: open
• Aortic valve: closed
• Left ventricular volume reaches its maximum, the end-diastolic volume (EDV), roughly 120 mL.
• Atrial contraction contributes the final 15% to 20% of ventricular filling, the atrial kick.

• Normally no sound.
• S4 may occur just before S1 if a stiff, poorly compliant ventricle resists filling, such as in left ventricular hypertrophy.

2. Isovolumetric ventricular contraction

• ECG: begins just after the QRS complex, which represents ventricular depolarization.
• Ventricular muscle begins to contract.
• Ventricular pressure rises rapidly.
• When ventricular pressure becomes greater than atrial pressure, the mitral valve closes.

• Mitral and tricuspid valve closure produces S1, the “lub.”
• S1 marks the beginning of ventricular systole.

• Both mitral and aortic valves are closed.
• No blood can enter or leave the ventricle.
• Therefore, ventricular volume stays constant, but pressure rises sharply.

3. Rapid ventricular ejection

• When left ventricular pressure exceeds aortic pressure, the aortic valve opens.
• Blood is expelled rapidly from the left ventricle into the aorta.
• Ventricular volume decreases quickly.
• Aortic pressure rises and reaches its peak.
• Most of the stroke volume is ejected during this part.

• Mitral closed
• Aortic open

4. Reduced ventricular ejection

• Ventricular contraction continues, but starts to weaken.
• ECG: the T wave appears, representing ventricular repolarization.
• Blood continues to flow into the aorta, but more slowly.
• Left ventricular and aortic pressures begin to fall.
• Ventricular volume continues to decrease until it reaches the end-systolic volume (ESV), roughly 50 mL.

• Mitral closed
• Aortic open

5. Isovolumetric ventricular relaxation

• The ventricle relaxes after ejection.
• When aortic pressure becomes greater than ventricular pressure, a brief backward tendency of blood closes the aortic valve.
• Closure of the aortic and pulmonary valves produces S2, the “dub.”
• S2 marks the end of ventricular systole and the beginning of diastole.
• Aortic valve closure produces the dicrotic notch on the aortic pressure trace.

• Both valves are now closed.
• No blood enters or leaves.
• Ventricular volume remains fixed at ESV.
• Ventricular pressure falls rapidly.

• Mitral closed
• Aortic closed

6. Rapid ventricular filling

• Ventricular pressure falls below atrial pressure.
• The mitral valve opens.
• Blood that accumulated in the left atrium during systole flows rapidly into the left ventricle.
• Ventricular volume rises quickly while ventricular pressure remains low.

• Mitral open
• Aortic closed

• An S3 can occur during rapid filling.
• S3 may be normal in children, young adults, and pregnancy.
• In older adults, it can suggest volume overload or heart failure.

7. Reduced filling: diastasis

• Passive filling continues, but at a slower rate as atrial and ventricular pressures become nearly equal.
• This is called diastasis.
• It is shortened or may disappear when heart rate rises.
• The next P wave initiates atrial systole, and the cycle repeats.

• Mitral open
• Aortic closed

One-line sequence to memorize

Key valve and sound sequence

High-yield points

• Systole = isovolumetric contraction + ventricular ejection.
• Diastole = isovolumetric relaxation + ventricular filling.
• During both isovolumetric phases, all valves are closed and ventricular volume does not change.
• S1 is closure of AV valves.
• S2 is closure of semilunar valves.
• Atrial systole becomes more important when ventricular filling time is reduced or ventricular compliance is decreased.