Download Control of the Cardiac Cycle

3.1.5 Control of the
Cardiac Cycle
L.O: to label and describe the 3 structures involved
in controlling the cardiac cycle
Starter: If systole means to contract and diastole
means to relax, can you put these into the correct
order of the cardiac cycle…
• Ventricular systole
Diastole!
• Diastole
• Atrial systole
Multiple-choice quiz
Diastole
Diastole!
Atrial Systole
Ventricular Systole
http://www.youtube.com/watch?v=xVofKdXOa4M
Listening to a beating heart: lub-dub
What does a doctor hear when they listen to a patients’ heart?
lub-dub,
lub-dub,
lub-dub,
lub-dub,
lub-dub,
lub-dub…
The sound of a heartbeat is the sound of the heart valves.
The “lub” is caused by
the closing of the valves leading to
the ventricles.
The “dub” is caused by
the closing of the valves
leading out of the heart.
Cardiac Cycle
Stage
Diastole
Atrial
Systole
Ventricular
Systole
Atrioventricular Semi lunar
valves
valves
Cardiac Cycle
Stage
Atrioventricular Semi lunar
valves
valves
Diastole
Open
Closed
Atrial
Systole
Open
Closed
Ventricular
Systole
Closed
Open
Blood Pressure
• Systolic pressure is the
pressure at which the blood
leaves the heart through the
aorta.
Systolic
Diastolic
< 100
< 60
100-139
60-89
Borderline 140-159
90-94
Hypertension
>94
< normal
• Diastolic pressure is the
minimum blood pressure in
the aorta.
Normal
• Blood pressure can be
measured with a
sphygmomanometer: first
reading is systolic and
second is diastolic then
represented as a fraction.
>159
1.
2.
3.
4.
?
5.
6.
Control of the Cardiac Cycle
Three stages of the cardiac cycle are
controlled by three structures:
Control of the Cardiac Cycle
The three stages of the cardiac cycle are
controlled by three structures:
1. Sinoatrial node
2. Atrioventricular node
3. Bundle of His
Control of the Cardiac Cycle
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter22/animation__conducting_system_
of_the_heart.html
http://www.bbc.co.uk/learningzone/clips/the-human-heart/12225.html
Past Exam Question Jan 2010
7 (a) The cardiac cycle is controlled by the
sinoatrial node (SAN) and the atrioventricular
node (AVN). Describe how. (5 marks)
Casualty Keywords!
‘He’s tachycardic!’
A fast heart rhythm that originates in one of the ventricles of the heart. Can
lead to ventricular fibrillation (a ‘quiver’ rather than a full contraction),
asystole (no cardiac activity) and sudden death.
‘We need to defib NOW!’
Defibrillation consists of delivering a therapeutic dose of electrical energy to
the affected heart with a device called a defibrillator. This should terminate
the dysrhythmia, and allows the sinoatrial node of the heart to re-establish
the correct rhythm.
Keyword Quiz!
Unjumble the keywords about the heart to
solve the hidden message at the bottom of
your sheet! Then solve the picture clue!