NATIONAL QUALIFICATIONS CURRICULUM SUPPORT
Human Biology
The Cardiovascular System
Teacher’s Guide
[HIGHER]
The Scottish Qualifications Authority regularly reviews
the arrangements for National Qualifications. Users of
all NQ support materials, whether published by
Learning and Teaching Scotland or others, are
reminded that it is their responsibility to check that the
support materials correspond to the requirements of the
current arrangements.
Acknowledgement
Learning and Teaching Scotland gratefully acknowledges this contribution to the National
Qualifications support programme for Human Biology.
The publisher gratefully acknowledges permission to use the following sources: diagram of the
lungs from http://www.oup.co.uk/oxed/children/oise/pictures/humans/lungs/, figure from
Oxford Illustrated Science Encyclopedia (OUP, 2003) copyright © Oxford University Press
2001, reprinted by permission of Oxford University Press; diagram of veins blood flow
washing line from http://www.merriam-webster.com/art/med/vein.gif, by permission. From
Merriam-Webster’s Medical Dictionary ©2011 by Merriam-Webster, Incorporated
(www.merriam-webster.com); diagram, Anatomy of the Aorta from
http://www.daviddarling.info/encyclopedia/A/aorta.html © Internet Encyclopedia of Science;
diagram, Standard ECG records from http://www.davita-shop.co.uk/ecg-instruments.html ©
DAVITA; diagram of Cardiac cycle from http://www.revisionworld.co.uk/a2-us-grades-1112/biology/physiology-transport/cardiac-cycle © Revisionworld.com; images of a pulmonary
vein, pulmonary artery and a body © Oxford Designers and Illustrators.
Every effort has been made to trace all the copyright holders but if any have been inadvertently
overlooked, the publishers will be pleased to make the necessary arrangements at the first
opportunity.
© Learning and Teaching Scotland 2011
This resource may be reproduced in whole or in part for educational purposes by educational
establishments in Scotland provided that no profit accrues at any stage.
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THE CARDIOVASCULAR SYSTEM (H, HUMAN BIOLOGY)
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Contents
Introduction
5
The structure and function of blood vessels
16
The exchange of materials between tissue fluid and cells
20
The structure and function of the heart
22
The cardiac cycle
26
The cardiac conducting system
30
Blood pressure
33
Pathology of cardiovascular disease
35
Thrombosis
37
Peripheral vascular disorders
37
Cholesterol and atherosclerosis
42
Blood glucose levels and vascular disease
43
Obesity
49
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TEACHER’S GUIDE
How to print PowerPoint notes
1.
Choose File, then Print.
2.
Choose Notes Pages from the Print What list.
3.
Click OK.
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Introduction
The Heart Revision PowerPoint contains nine slides.
Slide
Summary
1
Title
2
Lesson aim
3
Task 1
4
Task 2
5
Task 3
6
Task 4
7
Task 5
8
Answers for
Task 1
Answers for
Task 5
9
Resources required
Notes
 A3 version of diagram
 Label cards cut out
 Photocopies of diagram
to keep in notes
 Instruction card
 A3 paper
 Coloured pens
 Instruction card
 Cut out cards
 Two clamp stands
 String
 11 paper clips
 Instruction card
 Cut out question and
answer cards
1. Heart diagram
2. Heart labels
Answers on slide 8
 Cut out cards
 A3 diagram (Double
circulation)
 Photocopies of diagram
to keep in notes
 Instruction card
3. Blood flow cards
Answers on notes page for this
slide
4. Questions and answers
Answers = the order of cards
before they are cut out
5. Double circulation diagram
– no labels
6. Double circulation diagram
– labels
Answers on slide 9
The instruction cards are a printout of the PowerPoint slide for each task.
A useful website about the heart can be seen at:
http://www.bbc.co.uk/science/humanbody/body/factfiles/heart/heart.shtml .
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Previous knowledge
The following is assumed knowledge.
 The heart works as a double pump.
 Blood passing through the right side of the heart trav els to the lungs:
- Oxygen diffuses from the alveoli into the blood capillaries .
- Carbon dioxide diffuses from the blood capillaries to the alveoli .
 Blood passing through the left-hand side of the heart travels to the brain
and other body organs.
 The heart is made of muscle cells and is split into four chambers (right
atrium, right ventricle, left atrium and left ventricle) .
 The blood travels through arteries, then capillaries, then veins.
 Arteries carry blood away from the heart. Blood is pumped through
arteries at a high pressure.
 Arteries branch into smaller and smaller blood vessel s, eventually forming
capillaries, which are microscopic blood vessels that carry blood close to
all body cells to allow gas exchange to take place.
 Capillaries merge into one another, producing wider and wider blood
vessels, eventually forming veins.
 Veins carry blood towards the heart and contain valves to prevent blood
from flowing backwards. These are necessary as the blood is flowing at
low pressure and generally against the force of gravity.
 As blood flows away from the heart the pressure decreases.
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Resource 1: Heart diagram
Vena Cava
Aorta
Pulmonary Artery
Left Atrium
Right Atrium
Left Ventricle
Right Ventricle
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Resource 2: Heart labels
8
Aorta
Pulmonary artery
Left atrium
Pulmonary vein
Left ventricle
Right ventricle
Right atrium
Vena cava
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Resource 3: Blood flow cards
Vena
cava
Pulmonary vein
Left ventricle
Body
Left
Atrium
Right
Atrium
Right
Ventricle
Left
Ventricle
Pulmonary artery
Right atrium
Left
Atrium
Right
Atrium
Right
Ventricle
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Left
Ventricle
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Left atrium
Lungs
Left
Atrium
Right
Atrium
Right
Ventricle
Left
Ventricle
Aorta
Body
Right ventricle
Left
Atrium
Right
Atrium
Left
Ventricle
Right
Ventricle
Instructions
Cut out each of the cards and use a paperclip to attach them to the ‘washing
line’ in the order that blood flows through the body . The line starts and ends
with the body.
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Resource 4: Questions and answers
What is the name of the
blood vessels that carry
oxygenated blood?
Arteries
What is the name of the
blood vessels that carry
deoxygenated blood?
Veins
What is the name of the
blood vessels that deliver
oxygen to body cells and
pick up carbon dioxide?
Capillaries
What is the name of the
main artery that carries
oxygenated blood away from
the heart?
Aorta
What is the name of the
main vein that carries
deoxygenated blood back to
the heart?
Vena cava
What is the name of the
blood vessel that carries
blood to the lungs?
Pulmonary artery
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What is the name of the
blood vessel that carries
blood from the lungs back to
the heart?
Pulmonary vein
Which side of the heart deals
with oxygenated blood?
Left-hand side
Which side of the heart deals
with deoxygenated blood?
Right-hand side
What does the pulse
indicate?
Blood flowing through an
artery
Instructions
12
 Cut out each of the cards.
 Keep the questions and
answers in separate piles.
 Shuffle each pile.
 Match the question with the
correct answer.
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Resource 5: Double circulation diagram – no labels
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Resource 6: Double circulation diagram with labels
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Resource 7: Labels for double circulation diagram
Jugular vein
Pulmonary artery
Carotid artery
Pulmonary vein
Aorta
Coronary artery
Coronary vein
Vena cava
Jugular vein
Pulmonary artery
Hepatic artery
Hepatic vein
Hepatic portal vein
Gut arteries
Renal vein
Renal artery
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The structure and function of blood vessels
The Structure and Function of Blood Vessels PowerPoint
Slide
Summary
1
Title
2
Video clip
3
Arteries
4
Veins
5
Capillaries
6
Blood vessels
7
Task
Resources required
Notes
‘Blood vessels’ clip
(YouTube) 1 minute 9
seconds long
Notes on notes pages
diagrams/pictures
Notes on notes pages
diagrams/pictures
Notes on notes pages
diagrams/pics
Comparison of all three
blood vessels
Diagrams to label
The endothelium lining the central lumen of blood vessels is surrounded by
layers of tissue, which are different between arteries, capillaries and veins.
Four layers are found in both arteries and veins:

central lumen
- blood flows through here
- much smaller in arteries

tunica intema
- made of epithelium cells, lines the lumen and reduces friction as the
blood flows through the vessel

tunica media
- middle layer of smooth muscle cells, collagen and elastic fibres
- much more strong and thick in arteries, allowing them to stretch and
recoil to accommodate the surge of blood after each contraction of the
heart (creates the pulse)
- smooth muscle can contract or relax, causing vasoconstriction or
vasodilation to control blood flow.

tunica externa
- outer layer consisting of collagen fibres and some elastin fibres.
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Capillaries do not have such a complex structure as their role is to allow
exchange of materials via diffusion. They have a capillary wall that is made
up of one layer of epithelium cells and a lumen.
Veins contain valves that make sure that blood is only able to flow towards
the heart – it will not flow backwards. They are vital as most veins are
carrying blood back to the heart against the flow of gravity and at a very low
pressure.
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Resource 8: Blood vessels
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Resource 9: Blood vessels – answers
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The exchange of materials between tissue fluid and cells
Play the video clip ‘Capillary exchange’ (3 minute 1 second) from
http://www.youtube.com/watch?v=Q530H1WxtOw.
The blood carries many materials around the body. For example :
 oxygen, which is required for cellular respiration and energy release
 products of digestion, which are transported to the liver to be processed or
stored – eg glucose
 urea, which is produced in the liver when excess proteins are broken down
 hormones from the site of production to the necessary cells of the body .
Blood capillaries are vital for the exchange of materials between the blood
and cells of the body. They transport blood to every cell in the body.
Two ways in which materials are exchanged between blood capillaries and
body cells are:
 passive diffusion
- the movement of soluble molecules from areas of high concentration to
areas of low concentration without the need for energy
- body cells are surrounded by interstitial (tissue) fluid , which acts as an
intermediary between the substances that are moving between the
capillaries and the cells
- the interstitial (tissue) fluid essentially takes on the same compositi on
of small soluble molecules as the arterial blood travelling through the
capillary
 bulk flow (pressure filtration)
- occurs when there is more pressure inside the capillary than outside ,
and causes the fluid to be pushed out of the capillary, through pore s,
and into the interstitial (tissue) fluid
- can also be called pressure filtration or ultra filtration
- most plasma proteins are retained inside the capillary as they are too
large to fit through the pores.
Tissue fluid (interstitial fluid) supplies cells with glucose, oxygen and other
substances. Carbon dioxide and other metabolic wastes diffuse out of the
cells and into the tissue fluid to be excreted through the circulatory system.
The tissue fluid can return to the blood via diffusion/reabsorption thr ough the
capillary wall or travel into the lymphatic system from where it is returned to
the blood.
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Teaching ideas
Groups research each section and present/teach to the rest of the class .
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The structure and function of the heart
Activity – heart dissection
The following video clips can be shown:


Pig heart dissection video at
http://www.youtube.com/watch?v=U0BHYvGSp40 – from 1:19 onwards –
5 minutes 54 seconds in total.
Cardiac structure and function video at
http://www.youtube.com/watch?v=MgJ7o_OtY1U 4 min utes 21 seconds.
Cardiac function
The heart is made of three layers of cells:



endocardium – the layer of epithelial cells inside the heart
myocardium – the main component of the heart made up of cardiac
muscle cells
epicardium – the thin membrane that surrounds the heart .
The blood vessels that return blood to the heart are called veins.
The upper chambers of the heart are called the atria. They receive blood
returning to the heart from the body (Right Atrium or RA) and the lungs (Left
Atrium or LA).
Blood is transferred into the lower chambers , called ventricles. The ventricles
contract and pump blood out of the heart. Blood leaving the heart travels
though arteries.
The left and right ventricles pump the same volume of blood through the
aorta and pulmonary artery.
The heart is separated into two halves by the septum, which ensures that the
oxygen-poor blood in the right-hand side of the heart is kept separate from
the oxygen-rich blood of the left-hand side of the heart.
The valves of the heart prevent blood from flowing backwards.
Atrioventricular (AV) valves are found between the atria and the ventricles.
The aortic semilunar valve is found between the ventricle and aorta leaving
the left-hand side of the heart.
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The pulmonary semilunar valve is found between the ventricle and the
pulmonary artery leaving the right -hand side of the heart
The volume of blood pumped through each ventricle per minute is the cardiac
output (CO). CO is determined by heart rate and stroke volume:
CO = HR × SV
where HR is heart rate, the number of heart contractions in 1 minute, and SV
is stroke volume, the volume of blood pumped out by one ventricle during
one systole. Systole refers to the contraction of the heart, in this case
contraction of the ventricles.
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TEACHER’S GUIDE
Resource 10: Exterior and interior of the heart – to be labelled
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Resource 11: Exterior and interior of the heart with labels
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TEACHER’S GUIDE
The cardiac cycle
The cardiac cycle is the pattern of contraction (systole) and relaxation
(diastole) in one complete heartbeat:


ventricular diastole – relaxation of the ventricular muscles
ventricular systole – contraction of the ventricular muscles.
During diastole, the atria fill with blood from the vena cava and pulmonary
vein, and some of the blood flows into the ventricles.
Atrial systole is when both atria contract and transfer the remainder of the
blood through the AV valves to the ventricles.
Ventricular systole closes the AV valves and pumps the blo od out through the
semi lunar (SL) valves to the aorta and pulmonary artery.
In diastole the higher pressure in the arteries closes the SL valves.
The opening and closing of the AV and SL valves are responsible for the
heart sounds heard with a stethoscope.
The average length of one cardiac cycle is 0.8 seconds (based on a heart rate
of 75 beats per minute).
Heart murmurs are caused by abnormal patterns of cardiac blood flow. They
can be caused by valves that do not open or close fully.
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Resource 12: Cardiac cycle 1
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Resource 13: Cardiac cycle 2
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Resource 14: Cardiac cycle matching exercise
These cards should be cut up and the statements matched up with the stage of
the cardiac cycle.
Blood flows from the atria
into the ventricles through the
atrioventricular valves.
Atrial systole
The atria contract.
The semilunar valves close.
Ventricular systole
The ventricles contract.
The atrioventricular valves
close.
Blood flows through the
semilunar valves into the aorta
(from the left ventricle) and
the pulmonary artery (from
the right ventricle).
Heart muscle relaxes.
Diastole
The semilunar valves are
closed.
Blood flows into the atria
(right – from vena cava, left –
from pulmonary vein).
The atrioventricular valves are
open to allow blood to move
into the ventricles.
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The cardiac conducting system
The heart beat originates in the heart itself. Heart muscle cells are selfcontractile. This means they are able to contract and produce an
electrochemical signal, which is passed on to other cardiac muscle cells ,
causing them to contract. The conducting system (nervous control) of the
heart ensures that it beats in a co-ordinated manner.
The cells of the ventricles will beat on their own if they are not stimulated by
the sinoatrial node (see below), but they will contract at a slower rate. This
would make the cardiac muscles cells contract in a disorganised and random
way.
The autorhythmic cells of the sinoatrial node (SAN) or pacemaker set the rate
at which cardiac muscle cells contract.
The SAN is found at the top of the right atrium. The cells in this area contract
faster than the cells of other cardiac muscles, and set the rate for the rest of
the cardiac muscle cells in the heart. The electrical impulse that is generated
by the contracting cells in the SAN is passed through the left and right atria
to the atrioventricular node (AVN), which is found lower part of the right
atrium. When it reaches the AVN, the electrical impulse is conducted to the
cells in the ventricles of the heart.
Electrical impulses are conducted via conducting fibres , which form the
bundle of His, or AV bundle. The bundle of His is an area of specialised cells
found on the septum between the atria and ventricles of the right and left
sides of the heart. The fibres split into right and left branches, which supply
the papillary muscles. The papillary muscles attach to the atrioventricular
valves, then the rest of the ventricular myocardium . Smaller branches around
the muscle of the left and right ventricles are called the Purkinje fibres.
These impulses generate currents that can be detected by an
electrocardiogram (ECG). An ECG is used to measure the electrical changes
that take place in the heart.
The labels on the following diagram (Resource 15) are as follows:
 P (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 – the electrical recovery of the ventricles at the end of ventricular
systole.
An ECG is traced by placing electrodes on the surface of the body . These
pick up the electrical impulses that are produced by the beating heart. The
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tracings can be used to identify problems with the heart such as myocardial
infarction (heart attack).
The medulla regulates the rate of the SAN through the antagonistic action of
the autonomic nervous system (ANS). The ANS is part of the peripheral
nervous system and in control of the functions of the body that are not
conscious actions.
Sympathetic accelerator nerves (accelerans nerve) release adrenaline
(epinephrine), which increases the heart rate and the strength of the heart
muscle contractions. It can be activated due to stress and fear, for example.
Exercise increases heart rate because it stimu lates receptor cells in the carotid
arteries and aorta as well as the right atrium.
The carotid arteries and aorta detect increased levels of carbon dioxide in the
blood and transmit a message to the medulla, which in turn transmits a signal
to the heart via the sympathetic accelerator nerves.
The receptors in the right atrium detect the extra blood that is being pumped
back to the heart and causing the right atrium to become distended. These
receptors send impulses to the medulla, and subsequently the heart, via the
same sympathetic accelerator nerves.
Parasympathetic nerves (vagus nerve) release acetylcholine, which slows the
heart rate.
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Resource 15 ECG
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Blood pressure
Blood pressure changes in the aorta during the cardiac cycle. Measurement o f
blood pressure is performed using a sphygmomanometer. This uses an
inflatable cuff that stops blood flow and then deflates gradually, letting the
flow recommence. The blood starts to flow (detected by a pulse) at systolic
pressure. The blood flows freely through the artery (and a pulse is not
detected) at diastolic pressure.
A typical reading for a young adult is 120/70 mmHg. Hypertension is a major
risk factor for many diseases, including coronary heart disease.
A video (57 seconds) of blood pressure measurement can be seen at
http://www.youtube.com/watch?v=ElCbQMiBC6A&NR=1.
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Resource 16: Measuring blood pressure using a
sphygmomanometer
An inflatable cuff stops
blood flow and deflates
gradually.
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The blood starts to flow
(detected by a pulse) at
systolic pressure.
THE CARDIOVASCULAR SYSTEM (H, HUMAN BIOLOGY)
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The blood flows freely
through the artery (and a
pulse is not detected) at
diastolic pressure.
TEACHER’S GUIDE
Pathology of cardiovascular diseases
Atherosclerosis
Atherosclerosis is the accumulation of fatty material (consisting mainly of
cholesterol), fibrous material and calcium forming an atheroma or plaque
beneath the endothelium.
As the artheroma grows the artery thickens and loses its elasticity. The
diameter of the artery is reduced and blood flow is restricted, resulting in
increased blood pressure. This damage to arteries can mean that organs will
receive less blood than they require to function properly and, if the artery
ruptures, increases the risk of thrombosis, which can lead to heart attack or
stroke.
Hardening of the arteries is a natural process when people get older, but many
lifestyle choices can make some people more susceptible to this earlier in
their lives. Risk factors include smoking, a diet containing fatty food , a
sedentary lifestyle, being obese, having diabetes and having high blood
pressure.
Atherosclerosis is the root cause of various cardiovascular diseases , including
angina, heart attack, stroke and peripheral vascular disease.
The treatments for atherosclerosis aim to slow the progress of the condition
and prevent it from causing more damage and leading to potentially more
serious issues such as a heart attack. The treatments usually include
combining lifestyle changes with medication.
A video about the condition (2 minutes 1 second) together with a very good
source of information can be seen at
http://www.nhs.uk/Conditions/Atherosclerosis/Pages/Introduction.aspx .
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Resource 17: Atherosclerosis
Cross-section of an artery that shows how the build -up of plaque narrows the
diameter, obstructing and eventually blocking the flow of blood.
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Thrombosis
Atheromas may rupture, damaging the endothelium. The damage releases
clotting factors, which activate a cascade of reactions, resulting in the
conversion of the enzyme prothrombin to its active form , thrombin.
Thrombin then causes molecules of the plasma p rotein fibrinogen to form
threads of fibrin. The fibrin threads form a mesh that clots the blood, seals
the wound and provides a scaffold for the formation of scar tissue.
The formation of a clot (thrombus) is referred to as thrombosis. In some cases
a thrombus may break loose, forming an embolus that can travel through the
bloodstream until it blocks a blood vessel.
A thrombosis in a coronary artery may lead to a heart attack (myocardial
infarction). A thrombosis in an artery in the brain may lead to a stroke. In the
latter case cells are deprived of oxygen, leading to the death of the tissues.
Peripheral vascular disorders
Peripheral vascular disease is narrowing of the arteries due to atherosclerosis
of arteries other than those to the heart and br ain. The arteries to the legs are
most commonly affected. Pain is experienced in the leg muscles due to a
limited supply of oxygen.
A deep vein thrombosis (DVT) is a blood clot that forms in a deep vein , most
commonly in the leg. If the clot breaks off an d travels through the
bloodstream it may result in a pulmonary embolism.
A leaflet entitled ‘Reducing The Risk Of Stroke’ (Stroke Series SS3),
published by Chest, Heart and Stroke Scotland, can be downloaded from
http://www.chss.org.uk/stroke/reduce_your_risk_of_a_stroke/ . Students
should read the booklet and complete the questions or alternatively the
questions could be asked without the students having the booklet first.
A leaflet about Transient Ischaemic Attacks (TIAs) entitled ‘Understanding
TIAs’ (Stroke Series SS5), also published by Chest, Heart and Stroke
Scotland, can be downloaded from
http://www.chss.org.uk/stroke/transient_ischaemic_attacks.php . Again,
students can work with or without the booklet. If working without the
booklet, very little modification to the questions is needed
Video – DVT Prevention, 2 minutes 45 seconds.
http://www.youtube.com/watch?annotation_id=annotation_115462&feature=i
v&v=uS1RGbW8UbQ
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Resource 18: Reducing the risk of stroke – questions
10.
What does the Chest, Heart and Stroke Scotland ‘Reducing The Risk Of
Stroke’ (Stroke Series SS3) recommend that people have tested
regularly?
What does the systolic pressure record?
What does the diastolic pressure record?
What is the normal blood pressure agreed by most doctors?
What two methods do doctors have of lowering blood pressure ? Give
examples where appropriate.
Where is cholesterol manufactured?
Which three different fats are mentioned in the booklet?
Which family of drugs are used to medically lower cholesterol?
If someone has already suffered from a stroke or a TIA, they may be
prescribed blood-thinning drugs. Name one antiplatelet drug and one
anticoagulant.
What is the name of the preventative surgery described in the booklet?
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1.
2.
3.
4.
5.
6.
7.
8.
9.
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TEACHER’S GUIDE
Resource 19: Reducing the risk of stroke – answers
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
What does the Chest, Heart and Stroke Scotland ‘Reducing The Risk Of
Stroke’ (Stroke Series SS3) recommend that people have tested
regularly? Blood pressure.
What does the systolic pressure record? The pressure within blood
vessels when the heart contracts.
What does the diastolic pressure record? The pressure when the heart
fills up again.
What is the normal blood pressure agreed by most doctors? 120/70.
What two methods do doctors have of lowering blood pressure ? Give
examples where appropriate. Lifestyle changes and drug treatment.
Examples of lifestyle changes: stopping smoking, control weight, keep
active, moderate alcohol intake, reduce salt in the diet .
Where is cholesterol manufactured? The liver.
Which three different fats are mentioned in the booklet? Low-density
lipoproteins, high-density lipoproteins, triglycerides.
Which family of drugs are used to medically lower cholesterol? Statins.
If someone has already suffered from a stroke o r a TIA, they may be
prescribed blood-thinning drugs. Name one antiplatelet drug and one
anticoagulant. Antiplatelet drugs: aspirin, dipyridamole, clopidogrel;
anticoagulant drug: warfarin.
What is the name of the preventative surgery described in the booklet?
Carotid endarterectomy.
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TEACHER’S GUIDE
Resource 20: Understanding the risk of TIAs – questions
1.
2.
3.
4.
5.
What are the three most common symptoms of a TIA?
Which four other conditions give similar symptoms as TIAs?
What causes TIAs?
Name three tests that are usually carried out to diagnose TIAs .
Which two different types of drug treatment can be used to reduce the
risk of further TIA or stroke?
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Resource 21: Understanding TIAs – answers
1.
2.
3.
4.
5.
What are the three most common symptoms of a TIA? Weakness,
numbness, clumsiness, pins and needles on one side of the body, loss of
or disturbed vision, slurred speech or difficulty finding words.
Which four other conditions give similar symptoms as TIAs? Migraine,
epilepsy, anaemia and heart arrhythmia.
What causes TIAs? Atheroma – build up of fatty tissue in blood vessel
walls; embolus – blood clot or debris travelling in the bloodstream
until it becomes stuck.
Name three tests that are usually carried out to diagnose TIAs . Blood
pressure measurements, blood tests for blood sugar, cholesterol and
clotting, ECG, chest X-ray, CT scan, ultrasound scan of the carotid
arteries.
Which two different types of drug treatment can be used to reduce the
risk of further TIA or stroke? Anticoagulant and antiplatelet drugs.
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TEACHER’S GUIDE
Cholesterol and atherosclerosis
Most cholesterol is synthesised by the liver f rom saturated fats in the diet.
Cholesterol is a component of cell membranes and a precursor for steroid
synthesis.
Lipoproteins transport fatty acids and cholesterol in the blood. The two main
groups are high-density lipoproteins (HDL) and low-density lipoproteins
(LDL). HDL transports excess cholesterol from the body cells to the liver for
elimination. This prevents accumulation of cholesterol in the blood. LDL
transports cholesterol to body cells.
Most cells have LDL receptors that take LDL into the c ell, where it releases
cholesterol. Once a cell has sufficient cholesterol a negative feedback system
inhibits the synthesis of new LDL receptors and LDL circulates in the blood ,
where it may deposit cholesterol in the arteries , forming atheromas.
A higher ratio of HDL to LDL will result in lower blood cholesterol and a
reduced chance of atherosclerosis.
Regular physical activity tends to raise HDL levels ; dietary changes aim to
reduce the levels of total fat in the diet and to replace saturated with
unsaturated fats.
Drugs such as statins reduce blood cholesterol by inhibiting the synthesis of
cholesterol by liver cells.
Familial hypercholesterolaemia (FH) caused by an autosomal dominant gene
predisposes individuals to developing high levels of choles terol. FH genes
cause a reduction in the number of LDL receptors or an altered receptor
structure.
Genetic testing can determine if the FH gene has been inherited and it can be
treated with lifestyle modification and drugs.
Interesting information on FH can be seen at
http://www.library.nhs.uk/geneticconditions/viewresource.aspx?resID=12654
2.
www.healthcheck.nhs.uk/Library/FH_Guidance_August2010.doc
Teachers could go on to discuss genetic testing, how information is relayed to
other members of the family, the support network that is in place for people
receiving genetic testing and so on. See
http://www.ukgtn.nhs.uk/gtn/Home/Public.
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Blood glucose levels and vascular disease
Chronic elevation of blood glucose levels leads to the endothelium cells
taking in more glucose than normal, damaging the blood vessels.
As a result, atherosclerosis may develop, leading to cardiovascular disease,
stroke or peripheral vascular disease. Damage to small blood vessels caused
by elevated glucose levels may result in haemorrhage of blood vessels in th e
retina, renal failure or peripheral nerve dysfunction.
Regulation of blood glucose
Blood glucose levels are regulated via a negative feedback loop, which is
mediated by the actions of the hormones insulin and glucagon.
Pancreatic receptors respond to high blood glucose levels by causing
secretion of insulin, which activates the conversion of glucose to glycogen in
the liver, decreasing blood glucose concentration.
Pancreatic receptors respond to low blood glucose levels by producing
glucagon, which activates the conversion of glycogen to glucose in the liver ,
increasing blood glucose level.
During exercise and fight-or-flight responses glucose levels are raised by
adrenalin (epinephrine) released from the adrenal glands , stimulating
glucagon secretion and inhibiting insulin secretion.
Diabetes
A diabetic is unable to control their glucose levels. Vascular disease can be a
chronic complication of diabetes.
 Type 1 diabetes usually occurs in childhood.
 Type 2 diabetes or adult-onset diabetes typically develops later in life and
occurs mainly in overweight individuals.
A person with type 1 diabetes is unable to produce insulin and can be treated
with regular doses of insulin. In type 2 diabetes individuals produce insulin
but their cells are less sensitive to it. This insulin resistance is linked to a
decrease in the number of insulin receptors in the liver , leading to a failure to
convert glucose to glycogen. In both types of diabetes individual blood
glucose levels will rise rapidly after a meal an d the kidneys are unable to
cope, resulting in glucose being lost in the urine. Testing urine for glucose is
therefore often used as an indicator of diabetes.
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TEACHER’S GUIDE
The glucose tolerance test is used to diagnose diabetes. The blood glucose
levels of the individual are measured after fasting and 2 hours after drinking
250–300 ml of glucose solution.
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Resource 22: Matching exercise – insulin and glucagon
Activates the conversion of
glucose to glycogen
Secreted during periods of low
blood glucose, eg between
meals and during exercise
Decreases blood glucose
levels
Low levels continuously
secreted, higher levels
secreted after eating
Increases blood glucose
levels
Activates the conversion of
glycogen to glucose
Instructions
Copy the table below.
Cut out the statements and stick them into the correct column of the table.
Insulin
Glucagon
THE CARDIOVASCULAR SYSTEM (H, HUMAN BIOLOGY)
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TEACHER’S GUIDE
Resource 23: Matching exercise – insulin and glucagon answers
Insulin
Glucagon
Activates the conversion of
glucose to glycogen
Activates the conversion of
glycogen to glucose
Decreases blood glucose
levels
Increases blood glucose
levels
Low levels continuously
secreted, higher levels
secreted after eating
Secreted during periods of
low blood glucose, eg
between meals and during
exercise
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THE CARDIOVASCULAR SYSTEM (H, HUMAN BIOLOGY)
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TEACHER’S GUIDE
Resource 24: Type 1 and type 2 diabetes sentences
Instructions
Match each of the sentence beginnings to the correct sentence ending .
Sentence beginnings
Type 1 diabetes …
Type 2 diabetes …
A person with type 1 diabetes …
A person with type 2 diabetes …
A person with type 2 diabetes …
A person with type 1 diabetes …
Sentence endings
…occurs mainly in childhood.
…occurs later in life and mainly in obese people.
…is unable to produce insulin.
…produces insulin but their cells are less sensitive to it.
…is treated with regular doses of insulin.
…is treated first with changes in diet, weight and exercise.
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TEACHER’S GUIDE
Resource 25: Type 1 and type 2 diabetes sentences – answers
Type 1 diabetes…occurs mainly in childhood.
Type 2 diabetes…occurs later in life and mainly in obese people.
A person with type 1 diabetes…is unable to produce insulin.
A person with type 2 diabetes…produces insulin but their cells are
less sensitive to it.
A person with type 2 diabetes …is treated first with changes in
diet, weight and exercise.
A person with type 1 diabetes…is treated with regular doses of
insulin.
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Obesity
Obesity is a major risk factor for cardiovascular disease and type 2 diabetes.
It is characterised by excess body fat in relation to lean body tissue (muscle).
A body mass index (weight (in kilograms) divided by height (in metres)
squared) greater than 30 is used to indicate obesity. Accurate measurement of
body fat requires the measurement of body density.
Obesity is linked to high fat diets and low levels of physical activity. The
energy intake in the diet should limit fats and free sugars as fats have a high
calorific value per gram and free sugars require no metabolic energy to be
expended in their digestion.
Exercise increases energy expenditure and preserves lean tissue. Exercise can
help to reduce risk factors for cardiovascular disease by keeping weight under
control, minimising stress, reducing hypertension and improving HDL blood
lipid profiles.
The following are articles about obesity in the news:
http://www.scotland.gov.uk/Topics/Statistics/Browse/Health/TrendObesity
http://www.telegraph.co.uk/news/uknews/1564208/Scotland -is-second-in-theworld-for-obesity.html
http://www.heraldscotland.com/news/health/cost-of-obesity-could-reach-3bna-year-and-hurt-economic-growth-1.1008165
http://news.stv.tv/scotland/140591-shock-following-new-obesity-figures/
For this section the students could split into groups and prepare a poster ,
presentation or information leaflet on the topic or debate school meals
provision in the government drive to lower Scottish obesity.
http://www.show.scot.nhs.uk/publications/publication.asp?name=&org=%25
&keyword=obesity&category=1&number=10&sort=tDate&order=DESC&Submit=Go
http://www.who.int/en/
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