Cardiac Cycle

Question 1

What are the sounds heard with a stethoscope?

Answer 1

The valves closing making a LUB DUB noise.

Question 2

What is the cardiac cycle?

Answer 2

The events that occur from the beginning of one heart beat to the beginning of next.

Question 3

What is diastole?

Answer 3

The heart ventricles fill with blood and are relaxed.

Question 4

What is systole?

Answer 4

Ventricles contract and pump blood into the aorta (LV) and pulmonary artery (RV).

Question 5

What lasts for longer, diastole or systole?

Answer 5

Diastole is much longer than systole.
Almost double.
At 75bpm diastole is around 0.5 s whilst systole is 0.3.

Question 6

What are the five events in the cardiac cycle?

Answer 6

1. Passive Filling
2. Atrial Contraction
3. Isovolumetric Ventricular Contraction
4. Ventricular Ejection
5. Isovolumetric ventricular relaxation

Question 7

What occurs in passive filling?

Answer 7

The pressures in the atria and ventricles are around 0.
The AV valves open and blood flows into the ventricles.
The pressure in the arteries is higher in that of the ventricles and so the semi lunar valves are shut.

Question 8

How much do the ventricles fill by passive filling?

Answer 8

Around 80%

Question 9

What occurs in Atrial contraction?

Answer 9

The contraction of the atria completes ventricle filling and the end diastolic volume.

Question 10

What points of the ECG show relaxation and contraction of the ventricles?

Answer 10

The P wave shows atrial depolarisation and p-Q shows atrial contraction.

Question 11

On the ECG when does ventricular contraction occur?

Answer 11

After the QRS complex.

Question 12

What occurs in isovolumetric ventricular contraction?

Answer 12

As the blood enters the ventricles the pressure rises and when it exceeds that of the atria the AV valves close.
The semi lunar valve is still shut so no blood can leave or enter.
The tension rises around a closed volume (isovolumetric contraction)
Ventricular pressure rises very steeply.

Question 13

When is the first heart sound heard?

Answer 13

When the AV valve shuts (LUB)

Question 14

What happens during Ventricular Ejection?

Answer 14

The ventricular pressure exceeds artery pressure causing the semi lunar valves to open.
The SV is ejected leaving behind the end systolic volume.
The artery pressure rises and the ventricles relax. When the pressure falls below that of the artery’s the valve shuts.

Question 15

How is the volume of the stroke volume calculated?

Answer 15

SV= EDV - ESV

Question 16

What does the t wave on an ECG show?

Answer 16

Ventricular repolarisation

Question 17

What generates the second heart sound?

Answer 17

The closing of the semi lunar valves (DUB)

Question 18

What produces he Dicrotic notch in the aortic pressure curve?

Answer 18

The valve vibration

Question 19

What does the valve vibration produce in the aortic pressure curve?

Answer 19

The dicrotic notch

Question 20

What is isovolumetric ventricular relaxation?

Answer 20

The closing valves signals the begging.
The ventricles are again in a closed box and the tension falls around the closed box (isovolumetric relaxation).
When the ventricular pressure falls below that of the atria the AV valve opens and a new cycle begins.

Question 21

What does the first heart sound s1 signal?

Answer 21

The beginning of systole

Question 22

What does the second heart sound s2 signal?

Answer 22

The beginning of diastole

Question 23

What are the additional abnormal sounds?

Answer 23

S3 and S4

Question 24

What areas of the chest should be listened too?

Answer 24

The aortic area, pulmonary area, tricuspid area and mitral area.

Question 25

Why does arterial pressure never fall to zero?

Answer 25

Due to stretch and recoil to move the blood around.

Question 26

How would the pulse pattern of the JVP be described?

Answer 26

Wavey

Question 27

What are the 3 waves of the JVP pulse?

Answer 27

A- atrial contraction
C- bulging of tricuspid valve into atrium during Ventricular contraction
V- rise of the atrial pressure during atrial filling