C5 - Heart Function L2

1. TOPIC 5 – HEART FUNCTION
Understand the terms cardiac output, stroke volume and heart rate and the
relationship between them
Understand the role of blood carbon dioxide in changing heart rate, heart rate range
in response to exercise and the hormonal and nervous effects on the heart rate
Learning Outcomes:
A – Identify, describe and explain the key terms
related to the functioning of the heart
CJ, CE
B – Identify and describe the key terms related
to the functioning of the heart
SF, AC, JH, RM
C – Identify the key terms related to the
functioning of the heart
JB, JB, AA, GB
Do Now Task – Draw and label the cardiac cycle on a
heart

2. KEY TERMS
Understand the terms cardiac output, stroke volume and heart rate and the relationship between them
Understand the role of blood carbon dioxide in changing heart rate, heart rate range in response to exercise and
the hormonal and nervous effects on the heart rate
Stroke Volume – Volume of blood leaving the left ventricle per beat
(ml)
Ejection Fraction – Proportion of blood in left ventricle pumped out
each beat (%)
Cardiac Output – The total volume of blood leaving the left
ventricle per minute or Stroke volume x Heart rate

3. HEART RATE TO WORK LOAD
Understand the terms cardiac output, stroke volume and heart rate and the relationship between them
Understand the role of blood carbon dioxide in changing heart rate, heart rate range in response to exercise and
the hormonal and nervous effects on the heart rate
Resting heart rate is between 60-90bpm
When exercising your HR increases. It increases in direct
proportion to work intensity.
It keeps increasing until nearing exhaustion where at which point it
levels off giving you a maximum heart rate.
Maximum Heart Rate = 220- AGE
Your MHR =

4. TASK

5. HEART RATES
Understand the terms cardiac output, stroke volume and heart rate and the relationship between them
Understand the role of blood carbon dioxide in changing heart rate, heart rate range in response to exercise and
the hormonal and nervous effects on the heart rate
When workloads are kept constant at sub-maximal levels the HR
will rapidly increase then level off or plateau = Steady State HR
SSHR = indicates the optimal heart rate for exercise being done.
Increase or decrease the workload and a new SSHR will form after
1-2 minutes.

6. STROKE VOLUME CHANGES DURING EXERCISE
Understand the terms cardiac output, stroke volume and heart rate and the relationship between them
Understand the role of blood carbon dioxide in changing heart rate, heart rate range in response to exercise and
the hormonal and nervous effects on the heart rate
As the workload gets higher so does your stroke volume.
It peaks at 50% of maximum effort then levels out as it reaches
maximum effort.
This increase in stroke volume is because of two mechanisms

7. STARLINGS LAW
Understand the terms cardiac output, stroke volume and heart rate and the relationship between them
Understand the role of blood carbon dioxide in changing heart rate, heart rate range in response to exercise and
the hormonal and nervous effects on the heart rate
If more blood enters the ventricles
during diastole then the walls will
obviously stretch and contract more
forcefully.
This is Starlings Law.
This law is helped by the Venous
return mechanisms bringing blood
back to the heart quicker as it
flowing round the body quicker.

8. WITH INTENSITIES
Understand the terms cardiac output, stroke volume and heart rate and the relationship between them
Understand the role of blood carbon dioxide in changing heart rate, heart rate range in response to exercise and
the hormonal and nervous effects on the heart rate
At higher workloads the cardiac muscle contracts with greater force.
This is to tackle the fact that diastole is shorted when exercising
meaning less blood fills the atria.
Because of this there is a stronger more forceful contraction to
make sure as much blood is ejected as possible.
What happens to stroke volume?

9. EFFECT ON CARDIAC OUTPUT
Understand the terms cardiac output, stroke volume and heart rate and the relationship between them
Understand the role of blood carbon dioxide in changing heart rate, heart rate range in response to exercise and
the hormonal and nervous effects on the heart rate
Increased heart rate due to exercise and an increased stroke
volume has a dramatic effect on cardiac output.
Cardiac Output = Heart Rate x Stroke Volume
To work out cardiac output we need to do
bpm x ml of blood/1000(l)

10. REGULATION OF HEART RATE
Understand the terms cardiac output, stroke volume and heart rate and the relationship between them
Understand the role of blood carbon dioxide in changing heart rate, heart rate range in response to exercise and
the hormonal and nervous effects on the heart rate
Heart rate is increase due to the sympathetic nerve stimulating the
SAN to work faster.
But what makes these impulses get sent quicker?
 Increased brain activity
 Increased blood pressure
 Increase in Carbon Dioxide

11. CARBON DIOXIDE
Understand the terms cardiac output, stroke volume and heart rate and the relationship between them
Understand the role of blood carbon dioxide in changing heart rate, heart rate range in response to exercise and
the hormonal and nervous effects on the heart rate
Carbon dioxide makes the blood more
acidic and this is detected by the
chemoreceptors in our in our carotid
arteries.
The receptors send more impulses to
the control centre in the medulla
oblongata.
It then sends impulses through the
sympathetic nerve to stimulate the
SAN.

12. BARORECEPTORS
Understand the terms cardiac output, stroke volume and heart rate and the relationship between them
Understand the role of blood carbon dioxide in changing heart rate, heart rate range in response to exercise and
the hormonal and nervous effects on the heart rate
Baroreceptors pick up changes in blood pressure and when this
gets too high it send impulses through the parasympathetic
nervous system instead. The vagus nerve is used to channel these
impulses down to the SAN to dissimulate the SAN.
http://www.youtube.com/watch?v=G2nLL_O_U7w

13. INDEPENDENT WORK
Understand the terms cardiac output, stroke volume and heart rate and the relationship between them
Understand the role of blood carbon dioxide in changing heart rate, heart rate range in response to exercise and
the hormonal and nervous effects on the heart rate
Complete notes of effect of training on the heart function
Page 56-57
You can;
 Mind map
 Bullet point
 Poster

14. HTTP://WWW.YOUTUBE.COM/WATCH?V=OK0KWAGTCYS