Cardiac Cycle

Question 1

Electrical events in cardiac cycle

Answer 1

1)atrial Depolarisation and Repolarisation
2) Ventricular depolarisation and repolarisation

Question 2

Mechanical events

Answer 2

1) Atrial Systole
2) Atrial diastole
3) ventricular systole
4) ventricular diastole

Question 3

Duration of cardiac cycle

Answer 3

Total=0.8 sec (if heart rate is 75/min)
If heart rate is rate increases duration of cardiac cycle decreases

Atrial systole = 0.1
Ventricular systole = 0.3
Ventricular diastole = 0.5
Atrial diastole = 0.7

Question 4

Describe phases of ventricular systole and duration

Answer 4

Total duration = 0.3 sec
Phases
1) Isovolumetric contraction phase
= 0.05 sec
2) Rapid ejection phase (0.1sec)
3) Reduced ejection phase (0.15 sec)

Question 5

Ventricular Diastole phases and duration

Answer 5

Ventricular Diastole total ➡️ 0.5 sec

1) Protodiastole (0•04 sec)
2) Isovolumetric relaxation phase=0.06
3) first rapid filling phase (0.1 sec)
4)Redured filling plase(diastass) (0.2)
5)Last rapid filling phase (0.1 sec)

Question 6

Main mechanical events in each phase

Answer 6

1)Pressure changes in
Atria, ventricles
Aorta and Pulmonary artery

2) Volume changes in Ventricles

3) Valvular events

Question 7

JVP ➡️ Jugular venous pressure or jugular venous pulse

Waves ?

Answer 7

⭕️ 3 positive waves ➡️ avc

⭕️ 2 negative waves x&y descends

Question 8

Define Phonocardiogram

Answer 8

1)It is the recording of heart
Sounds
2)heart sound appears as waves
3)They are oscillograph recording by placing a microphone to detect
the low frequency sound
4)The heart sound can be amplified & recorded on a high speed recording apparatus

Question 9

Define Atrial systole and describe the events occurring

Answer 9

1)Atrial systole begins from peak of P wave to peak of QRS complex
2)Both atria contract
3)Atrial pressure increases which is slightly more than ventricular pressure
4)Right atrial pressure reflects to internal jugular vein which is in direct contact with right atrium causing
“a wave “ in JVP
5)Last 30 % of ventricular filling occurs during this phase (atrial systole)
6)The vibration caused by gushing/inrush of blood from atria to ventricle produces 4th heart sound which is recorded in phonocardiogram
7)Ventricular volume = EDV =130 ml