AS Level Physical AS Level Physical EducationEducation

PE 1 – The articulate PE 1 – The articulate PerformerPerformer

Cardiac CycleCardiac Cycle

Karen Vaughan JonesKaren Vaughan Jones

OutcomesOutcomes

By the end of this lesson you should By the end of this lesson you should know:know:

The function of the cardiac cycle The function of the cardiac cycle during blood transportationduring blood transportation

Understand the specific details of a Understand the specific details of a systole and diastolesystole and diastole

Understand the conduction system of Understand the conduction system of the heartthe heart

The cardiac cycleThe cardiac cycle

As the blood travels around the heart As the blood travels around the heart a cardiac cycle occursa cardiac cycle occurs

A cardiac cycle occurs in ONE A cardiac cycle occurs in ONE COMPLETE HEARTBEATCOMPLETE HEARTBEAT

This includes the filling of the heart This includes the filling of the heart with blood – DIASTOLE with blood – DIASTOLE

Also includes the emptying of the Also includes the emptying of the blood in to the arterial system – blood in to the arterial system – SYSTOLE SYSTOLE

Stages of the cardiac cycle Stages of the cardiac cycle Each cycle takes 0.8 seconds and on Each cycle takes 0.8 seconds and on

average 72 times per minuteaverage 72 times per minute Four stages to each heartbeatFour stages to each heartbeat Diastole – atrial and ventricularDiastole – atrial and ventricular Systole – atrial and ventricularSystole – atrial and ventricular Each stage is dependent on whether the Each stage is dependent on whether the

chambers of the heart are filling with blood chambers of the heart are filling with blood while the heart is relaxing – while the heart is relaxing – DiastoleDiastole

Or whether they are emptying which occurs Or whether they are emptying which occurs when the heart is contracting - when the heart is contracting - SystoleSystole

ActivityActivity

Using the notes provided – Using the notes provided – summarise the four stages of a summarise the four stages of a cardiac cycle on the ohp sheetcardiac cycle on the ohp sheet

Recap: Recap:

1.1. Atrial diastoleAtrial diastole

2.2. Ventricular diastoleVentricular diastole

3.3. Atrial systoleAtrial systole

4.4. Ventricular systoleVentricular systole

1. Atrial diastole1. Atrial diastole

Upper chambers of the heart are filled Upper chambers of the heart are filled with blood returning from:with blood returning from:

The body via the venae cavae to the The body via the venae cavae to the right atriumright atrium

The lungs via the pulmonary vein to The lungs via the pulmonary vein to the left atriumthe left atrium

The atrio-ventricular valves are shut at The atrio-ventricular valves are shut at this moment, but as volume of blood this moment, but as volume of blood increases the AV valves open to increases the AV valves open to allow…allow…

Atrial diastoleAtrial diastole

2. Ventricular diastole2. Ventricular diastole

As soon as the atrio-ventricular As soon as the atrio-ventricular valves open the second stage of the valves open the second stage of the cardiac cycle occurscardiac cycle occurs

As the ventricles fill with blood the As the ventricles fill with blood the semi-lunar valves remain shutsemi-lunar valves remain shut

The atria now contractThe atria now contract

Ventricular diastoleVentricular diastole

3. Atrial systole3. Atrial systole

As the atria contract, atrial systole As the atria contract, atrial systole occurs which ensure all the blood is occurs which ensure all the blood is emptied in to the ventriclesemptied in to the ventricles

The pressure increases – AV valves The pressure increases – AV valves shutshut

Atrial systoleAtrial systole

4. Ventricular Systole 4. Ventricular Systole

Ventricular pressure increases – overcomes Ventricular pressure increases – overcomes the pressure in the aorta and the pulmonary the pressure in the aorta and the pulmonary arteryartery

Semi-Lunar valves open – ventricles Semi-Lunar valves open – ventricles contract contract

Blood from the right ventricle- pulmonary Blood from the right ventricle- pulmonary arteryartery

Blood from the left ventricle – aortaBlood from the left ventricle – aorta Once completed – SL valves closeOnce completed – SL valves close Cycle is completeCycle is complete

Ventricular systoleVentricular systole

Timings of systole and diastoleTimings of systole and diastole

Conduction systemConduction system

The conducting system relies on The conducting system relies on transmissions of impulses and transmissions of impulses and consists of cardiac muscle cells and consists of cardiac muscle cells and conducting fibres that are specialised conducting fibres that are specialised for initiating impulses and rapid for initiating impulses and rapid conduction throughout the heart. conduction throughout the heart.

They initiate the normal heartbeat They initiate the normal heartbeat and co-ordinate contraction of the and co-ordinate contraction of the heart chambers heart chambers

Unlike skeletal muscle – heart Unlike skeletal muscle – heart produces its own impulse – myogenicproduces its own impulse – myogenic

Begins at the SA node sino atrial Begins at the SA node sino atrial