1. B – The Cardiovascular System
The structure and function of arteries, capillaries and veins
The structure and function of the heart
Pathology of cardio vascular disease (CVD)
Blood glucose levels and obesity

2. KA 6: The structure and function of the heart
2.6 Key Topics
REVISION:
Structure of the heart
(D) Blood Pressure
(A)
Cardiac function and cardiac output
(B) Cardiac cycle
(C)
The structure and function of cardiac conducting system

3. KA 6c: Learning Outcomes
Give another name for the pacemaker
Describe the action of the SAN on the cardiac muscle cells, including how this stimulates the AVN
Identify SAN and AVN locations in a diagram
State the role of an ECG
Interpret ECG graphs in order to calculate heart rate
State that the heart beat can be regulated by both nervous and hormonal control
State the role of medulla and the ANS
Name the 2 nerves that can release hormones
State the names of these 2 hormones and describe the effect they have on the heart beat

4. Cardiac Conducting System
The events of the cardiac cycle are brought about by the activity of the heart’s pacemaker, or sino-atrial node (SAN)
It is located in the wall of the right atrium

5. Cardiac Conducting System
The SAN is a small region of specialised tissues that contains auto-rhythmic cells.
These cells initiate electrical impulses that make the cardiac muscle cells contract at a certain rate.

6. Cardiac Conducting System
The timing of cardiac cells contracting is controlled by the impulse from the SAN:
Spreading through the atria and
then travelling to the atrio-ventricular node (AVN) and
then through the ventricles.
These impulses generate currents that can be detected by an electrocardiogram (ECG).

7. P wave
QRS complex
T wave

8. ECGs
This electrocardiogram (ECG) shows one cardiac cycle

9. ECGs
An ECG measures the electrical changes that take place in the heart.
P wave – the wave of electrical impulses spreading over the atria from the SAN
Q-R-S complex – the electrical impulses through the ventricles
T wave – the electrical recovery of the ventricles at the end of ventricular systole.

10. The person’s heart beat is: ______ bpm
Answer = B
The person’s heart beat is: ______ bpm

13. KA 6c: Learning Outcomes
Give another name for the pacemaker
Describe the action of the SAN on the cardiac muscle cells, including how this stimulates the AVN
Identify SAN and AVN locations in a diagram
State the role of an ECG
Interpret ECG graphs in order to calculate heart rate
State that the heart beat can be regulated by both nervous and hormonal control
State the role of medulla and the ANS
Name the 2 nerves that can release hormones
State the names of these 2 hormones and describe the effect they have on the heart beat

14. What do you remember? THINK/PAIR/SHARE – 2 minutes!
What are 3 main parts of the brain?
What do they do?
The brain is part of which body system?
What do nerves do?
What do hormones do?

15. Nervous System
Central NS
Brain
Spinal cord
Peripheral NS
Somatic NS
Autonomic NS
Sympathetic
Parasympathetic

16. Para - sympathetic nerve
Nervous System
Central NS
Brain
Spinal cord
Peripheral NS
Somatic NS
Autonomic NS
Sympathetic nerve
Para - sympathetic nerve
Nor-epinephrine
Acetylcholine
Control centre
Impulses can be sent along both of these nerves to the heart. The heart rate depends on which system exerts a greater influence over the heart.

17. Tasks! Read page 168, from the title ‘regulation’ onwards
Stick in your diagram and label it using page 168 of the textbook
Write the title: The conducting system of the heart & how it is controlled
Complete the missing words exercise and stick it in!

18. Wordbank! Acetylcholine Medulla Antagonistic Atrium Parasympathetic
Autonomic
AVN
Sympathetic
Speeds up
Contract
Slows down
Diastole
Ventricles
Ventricular systole
Impulses

19. Impulses originate in the control centres in the _________
The conducting system of the heart is controlled by the _________ nervous system
It is made up of the sympathetic and ___________systems. These two systems are _________in action
The sympathetic nerve _________the heart rate and parasympathetic nerve _________the heart rate
Impulses originate in the control centres in the _________
The hormone nor-adrenaline (nor-epinephrine) is released by _________accelerator nerves, whereas the hormone _________is released by the slowing parasympathetic nerves.
The pacemaker or SAN is located in the right _________
Once stimulated, the SAN starts producing _________and contracts
These impulses cause the atria to _________ (atrial systole)
This then stimulates the _________, which is found at the junction between the atria and ventricles
The impulse from the AVN is carried by conducting nerves, which spread out over the _________.
This causes the contraction of ventricles (_________________), followed by relaxation (____________)
autonomic
parasympathetic
antagonistic
Speeds up
Slows down
medulla
sympathetic
acetylcholine
atrium
impulses
contract
AVN
ventricles
diastole
Ventricular systole

20. Think!
Why does your heart rate increase during exercise?

21. Hormonal Regulation of SAN
If stressed or during periods of exercise, the sympathetic nervous system acts on the adrenal glands, causing the release of adrenalin into the blood stream.
Upon reaching the SAN in the heart, the adrenaline causes the SAN to generate cardiac impulses at a higher rate, therefore bringing about an increase in heart rate!

22. Re-cap!
Don’t worry about advanced language:
Pulmonary valve / aortic valve = SL valves
Depolarisation = contraction
Repolarisation = relaxation
Further details on P QRS T graph

23. KA 6c: Learning Outcomes
Give another name for the pacemaker
Describe the action of the SAN on the cardiac muscle cells, including how this stimulates the AVN
Identify SAN and AVN locations in a diagram
State the role of an ECG
Interpret ECG graphs in order to calculate heart rate
State that the heart beat can be regulated by both nervous and hormonal control
State the role of medulla and the ANS
Name the 2 nerves that can release hormones
State the names of these 2 hormones and describe the effect they have on the heart beat