Cardio Respiratory - Week 2 Mechanical Events of the Cardiac cycle

Question 1

Draw and label a Wigger’s diagram, ECG for the left side of the heart and volume changes for the left ventricle (5)

Answer 1

Check notes week 2 cardio respiratory pre work

Question 2

Draw and describe Wigger’s diagram for Ventricular diastole (7)

Answer 2

Check notes week 2 cardio respiratory pre work

Heart is at rest

LA pressure > LV pressure

Therefore AV valve is open

Blood going into ventricle

Aortic pressure > LV pressure

Therefore semilunar valve is shut

Question 3

Draw and describe Wigger’s diagram for atrial systole (7)

Answer 3

Check notes week 2 cardio respiratory pre work

Question 4

Draw and describe earlier stages of ventricular systole (7)

Answer 4

Check notes week 2 cardio respiratory pre work

ECG – QRS complex
Q-R rapid depolarisation through
the bundle of His – bundle
branches toward the apex
R-S depolarisation spreads up the
wall of the heart
Ventricular depolarisation (leads to
ventricular contraction)
Ventricular pressure becomes
greater than atrial pressure
Mitral valve closes
First heart sound “lub”
(tricuspid valve also closes)

Question 5

What happens during earlier stages of ventricular systole (5)

Answer 5

Aortic valve – Shut
Mitral Valve – Shut
Ventricles contract – left ventricular
pressure goes up
Ventricle is sealed so the volume
does not change ‘isovolumic’

Question 6

Draw and describe ventricular systole (7)

Answer 6

Check notes week 2 cardio respiratory pre work

Ventricular contraction continues
Therefore, ventricular pressure
continues to rise.
When it exceeds the aortic pressure
the aortic (semilunar) valve opens
(i.e. pressure exceeds the
‘afterload’)
Blood can be ejected from the
ventricles into the aorta

Question 7

Draw and describe latter stages ventricular systole (7)

Answer 7

Check notes week 2 cardio respiratory pre work

ECG – T wave
Ventricles repolarising
Therefore ventricles relax
Blood ‘attempts’ to flow back from
aorta into the ventricle
Ventricular pressure < aortic
pressure
Aortic valve closes

Question 8

Draw and describe end of ventricular systole (7)

Answer 8

Check notes week 2 cardio respiratory pre work

Question 9

Draw and describe early stages of ventricular diastole (7)

Answer 9

Check notes week 2 cardio respiratory pre work

Aortic valve – Shut
Mitral Valve – Shut
Ventricles relax– left ventricular
pressure goes down
Ventricle is sealed so the volume
does not change ‘isovolumic’

Question 10

When does the metal valve open and where can this be seen on Wigger’s diagram? (3)

Answer 10

Check notes week 2 cardio respiratory pre work

When atrial pressure exceeds
ventricular pressure, mitral valve
opens

Question 11

Draw and describe ventricular diastole (7)

Answer 11

Check notes week 2 cardio respiratory pre work

The valve opening allows blood
that has accumulated in the atria to
enter the ventricle
Both the atria and ventricle are
relaxed but…
Atrial pressure > ventricular
pressure
This begins a passive filling of the
ventricle during ventricular
diastole