CARDIAC CYCLE AND JVP

Question 1

P WAVE DEPICTS

Answer 1

THE FIRING OF THE SA NODE AND ATRIAL DEPOLARISATION

Question 2

PR INTERVAL DEPICTS

Answer 2

THE TIME TAKEN FOR THE ACTION POTENTIAL TO SPREAD THROUGHOUT THE ATRIUM AND AV NODE

Question 3

PR SEGMENT INDICATES

Answer 3

NO VOLTAGE DETECTED D/T ATRIAL MUSCLE STILL DEPOLARISING WHILE VENTRICLE MUSCLE IS RESTING

Question 4

QRS DEPICTS

Answer 4

VENTRICULAR DEPOLARISATION

Question 5

ST SEGMENT DEPICTS

Answer 5

THE VENTRICULAR IS DEPOLARISING WHILE THE ATRIAL MUSCLE STILL IN RESTING PHASE

Question 6

T WAVE DEPICTS

Answer 6

VENTRICULAR REPOLARISATION

Question 7

WHY T WAVE IS BROADER THAN R WAVE?

Answer 7

BECAUSE REPOLARISATION IS NOT AS SYNCHRONISED AS THE DEPOLARISATION

Question 8

BRIEFLY DESC MECHANICAL EVENTS

Answer 8

1. LATE DIASTOLE
   - BOTH ATRIUM AND VENTRICLES ARE RELAX AND THE VENTRICLES ARE FILLED PASSIVELY.
2. ATRIAL SYSTOLE
   - THE ATRIUM IS CONTRACTING TO PROVIDE A FORCE SO THAT THE BLOOD CAN PUMP INTO THE VENTRICLE.
3. ISOVOLUMIC VENTRICULAR CONTRACTION
   - THE VENTRICLE IS CONTRACTING.
   - THE PRESSURE OF THE VENTRICLE IS JUST ENOUGH TO CAUSE THE AV VALVE TO CLOSE, HOWEVER IT IS NOT SUFFICIENT TO CAUSE THE SEMILUNAR VALVE TO OPEN.
4. VENTRICULAR EJECTION
   - THE VENTRICLE PRESSURE IS RISING IN WHICH IT IS MORE THAN THE AORTIC PRESSURE.
   - THEREBY THE SEMILUNAR VALVE IS NOW OPEN.
   - HENCE, BLOOD CAN BE PUMP INTO THE AORTA.
5. ISOVOLUMIC VENTRICULAR RELAXATION
   - THE VENTRICLE BEGIN TO RELAX, HENCE THE PRESSURE START TO FALL.
   - THE FALLING OF THE PRESSURE MORE THAN THE AORTIC PRESSURE CAUSING THE SEMILUNAR VALVE TO SNAP CLOSE.

Question 9

WHY THE TIME TAKEN FOR DIASTOLE IS LONGER THAN SYSTOLE?

Answer 9

BECAUSE
1. TO ALLOW VENTRICULAR FILLING
2. CORONARY ARTERY FLOW

Question 10

1. MIDDLE OF P WAVE CORRESPOND TO:
2. MIDDLE OF T WAVE CORRESPOND TO:
3. PEAK OF R WAVE CORRESPOND TO:

Answer 10

1. MIDDLE OF P WAVE CORRESPOND TO: THE BEGINNING OF THE ATRIAL SYSTOLE
2. MIDDLE OF T WAVE CORRESPOND TO: BEGINNING OF THE VENTRICULAR DIASTOLE
3. PEAK OF R WAVE CORRESPOND TO: BEGINNING OF THE VENTRICULAR SYSTOLE

Question 11

DESC BRIEFLY THE PRESSURE CHANGES IN WIGGER’S DIAGRAM.

Answer 11

1. AFTER FILLING THE VENTRICLE, THE VENTRICLE START TO CONTRACT (SYSTOLE), THEREBY THE ISOVOLUMIC VENTRICULAR CONTRACTION OCCUR. IN THIS PHASE, THE PRESSURE OF THE VENTRICLE START TO RISE FROM 10MMHG TO 80MMHG.
2. ONCE THE PRESSURE OF THE VENTRICLE REACH 80MMHG, IT INDICATES THAT THE PRESSURE OF THE VENTRICLE IS NOW MORE THAN THE AORTIC PRESSURE. THEREBY THE AORTIC VALVE WILL OPEN IN THIS PHASE.
3. THE PRESSURE OF THE AORTA AND THE LEFT VENTRICLE WILL SIMULATANEOUSLY INCREASE UNTIL IT REACHES 120MMHG , THEN THEY WILL START TO FALL AGAIN TILL 80MMHG. AS A RESULT, THE AORTIC VALVE WILL CLOSE.
4. THEN THE VENTRICLE WILL START TO RELAX. IN THIS PHASE, THE VENTRICLE WILL BEGIN THE ISOVOLUMIC VENTRICULAR RELAXATION. THE PRESSURE OF THE VENTRICLE WILL CONTINUE TO FALL TILL IT REACH 10MMHG.
5. THE AORTIC PRESSURE IS MAINTAINED IN ITS DIASTOLIC PRESSURE WHICH IS AT 80MMHG TO ENSURE CONTINOUS PERFUSION OF ORGAN IS HAPPENING DURING VENTRICULAR DIASTOLE.
6. ONCE THE VENTRICULAR PRESSURE FALL BELOW THE ATRIAL PRESSURE, THE MITRAL VALVE WILL OPEN AND THIS WILL ALLOW RAPID VENTRICULAR FILLING.
7. WHEN THE PRESSURE OF THE VENTRICLE FALL EVEN FURTHER, THERE WILL BE NO BLOOD OR VERY LITTLE AMOUNT OF BLOOD IS BEING PUMP INTO THE VENTRICLE RESULTING IN REDUCE VENTRICULAR FILLING PHASE.