Transcript GCSE Physical Education

GCSE Physical Education
The Circulatory System
At the end of this topic you
should know the following…
• The role and components of the circulatory
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system;
The structure of the heart;
How the circulatory system works;
Definitions of…
• Heart rate, stroke volume, cardiac output;
The roles and characteristics of the 3 types of
blood vessels;
The functions of blood cells;
How the circulatory system is affected by
exercise.
The Circulatory System
Components are…
• The heart
• Blood vessels
• Blood
Major functions include…
• Transport of oxygen & carbon dioxide to
& from muscles
• Temperature regulation
• Preventing infection
The Heart
• Use your textbooks to
1.
2.
3.
4.
5.
find out the correct
answers to the
following questions...
The heart is a special
type of muscle
called…?
Why is it special?
What is its main job?
Why is the heart often
described as a ‘double
pump’.
Approximately how big
do you think the heart
is?
The Structure of the Heart
Use your text books to label the different parts of the heart
Group task
• Organise yourselves into groups of 4-5
people.
• You will need a sheet of A3 paper, a plastic
wallet with labels inside, a pen/marker &
paper glue.
• Arrange the labels to accurately illustrate the
structure of the heart, and the flow of blood
around the cardiovascular system.
• Link your labels together by drawing arrows
between them where appropriate.
Group task
When to use…
• Early to check KS3
science knowledge.
• Late to check KS4
science knowledge.
• Revision.
Differentiation…
• Teacher decides on
groups, or let
students choose.
• Test answers with
text book.
• Use more able
student as observer.
• B&W and/or red &
blue labels.
The Structure of the Heart
The Circulatory System
• Complete the worksheet.
• If necessary, use your textbooks to help
you.
• Ask if you are unsure about any of the
words.
Blood vessels
Blood vessels are needed to transport blood
around the body
• Arteries: carry oxygenated blood away
from the heart to the organs & muscles
• Veins: carry de-oxygenated blood back to
the heart. This blood carries excess carbon
dioxide and other waste products
• Capillaries: the smallest blood vessels,
which lie close to the muscle allowing oxygen
and carbon dioxide to pass to & from the
blood & the muscles
Blood vessels – over to you
• Use your textbooks to find out about
the different blood vessels.
• With a partner list the similarities and
differences between arteries, veins and
capillaries.
Vessels
Arteries
Capillaries
Veins
Characteristics
Connective tissue & smooth muscle;
‘elastic’ properties; blood travels
under high pressure; oxygenated
blood way from heart; linked to
arterioles.
One cell thick; high density network;
allow gaseous exchange; linked to
arterioles & venules.
Smooth muscle; non ‘elastic’; blood
travels under low pressure; valves
present; de-oxygenated blood to
heart; linked to venules.
Blood pressure
 BP: pressure under which the blood
travels as it is ejected from left ventricle
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Blood vessel constriction increases BP;
dilation reduces BP
DIASTOLE: heart is relaxed, BP is
reduced
SYSTOLE: heart contracts, BP is
increased
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BP during aerobic exercise
Systolic BP increases in direct
proportion to increased exercise
intensity
Diastolic BP changes little if any during
endurance exercise, regardless of
intensity
• Muscles help
squeeze the blood
through the veins
back to the heart.
• Note how valves
work together.
Blood – what is it??
• Blood accounts for ~ 8% of
total body weight.
• It is made up of cells &
platelets, which are
suspended in plasma.
• There are 3 types of blood
cells:
• Red blood cells
• White blood cells
• Platelets
Homework Task
• Find out about red & white blood cells
and platelets (use your textbooks, other
books in the library, CD ROMS or
internet).
• In your own words, describe the
function of each of the 3 blood cells.
Blood cells
• Red blood cells (erythrocytes) are extremely small and
give the blood its red colour. A typical adult has about 4.8
to 5.4 million red blood cells.
• The main function of these cells is to transport oxygen and
carbon dioxide around the body. Oxygen is transported
via a chemical called haemoglobin.
• White blood cells (leukocytes) have the function of
protecting the body from bacteria, viruses, infections and
foreign bodies
• Platelets (thrombocytes) are small cell fragments
which help the blood to clot.
Heart Rate
• Heart rate…the number of times per minute
that the heart contracts.
• RHR averages 60 to 80 beats per minute
(bpm); can range from 28 bpm to above 100
bpm.
• Tends to decrease with age and with
increased cardiovascular fitness.
• Therefore resting heart rate is often used to
indicate a person’s fitness level.
• Is affected by environmental conditions such
as altitude and temperature
What other factors can affect resting heart rate?
Stroke volume
• Stroke Volume…the amount of blood pumped
by the heart per contraction (beat).
• SV increases with increasing rates of work.
• Influences aerobic endurance capacity when
working maximally.
Stroke Volume Increases During Exercise
• Frank Starling mechanism—more blood in the
ventricle causes it to stretch more and contract
with more force.
Cardiac output
• Cardiac Output… the amount of blood pumped by the
heart per minute.
• Resting value of cardiac output (Q) is approximately 5.0
L/min.
• Q increases directly with increasing exercise intensity to
between 20 to 40 L/min.
• Value of increase varies with body size and fitness level.
How can you calculate the Cardiac Output?
• Q = HR x SV
• When exercise intensity exceeds 40% to 60% of
maximum, further increases in Q are more a result of
increases in HR than SV.
CHANGES IN HR, SV, AND Q
The Heart in Action
Heart Rate
[beats per minute]
Stroke Volume
[mls per beat]
Cardiac Output
[litres per minute]
Homer
Flanders
100
65
90
70
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?
Complete the table [remember there are 1000ml in a litre!]
Measuring pulse rate
The Heart in Action
• The data on the next slide show a person’s
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heart rate before and after a short period of
intense exercise.
Using graph paper or a spreadsheet package
(e.g. Excel), plot a line graph.
Use Time on the horizontal axis and Heart
Rate on the vertical axis.
Draw a smooth curve through the points and
give your graph a title.
Describe what happens to the person’s heart
rate during the 15 minutes it was measured.
TIME [minutes]
HR [beats per minute]
0
60
1
64
2 [EXERCISE STARTS]
68
3
130
4
150
5
161
6
171
7
167
8
110
9
98
10
90
11
82
12
74
13
68
14
64
15
60
Heart Rate During Different
Activities
• Resting:
68 bpm
• Brisk uphill
walking:
142 bpm
• Running
uphill:
188 bpm
• Compare the data on the left by…
• Drawing a bar chart.
• Writing a few sentences to explain
why the values have changed.
• Working out the percentage of the
person’s maximum heart rate at
each intensity. This is estimated as
220 – age (the data is from a 17
year old person).
Circulatory system & PEP
• What type of activities/training
programmes might be affected by the
efficiency of the circulatory system?
• Baseline data: measure RHR, HR max &
HR rec., plus BP – are there changes
during and after the training
programme?
• If so, what are the changes caused by?
Homework
1. What are the components of the circulatory system? (3 marks)
2. What type of muscle makes up the heart, why is it special? (2 marks)
3. There are three types of blood vessels. Describe each type. (5 marks)
4. Label the diagram below, which demonstrates passage of blood through the
heart and around the body.
(10 marks)