1. Higher Human Biology Unit 2 – Physiology and Health
Section 15 – Pathology of Cardiovascular Disease (CVD)

2. a – Process of Atherosclerosis
We will be learning…
To be able to describe the process of atherosclerosis
To be able to state and explain its effect on arteries and blood pressure
To be able to describe cardiovascular diseases (CVD) e.g. angina, heart attack, stroke and peripheral vascular disease.

3. Atherosclerosis
Atherosclerosis is the accumulation of lipid containing material (consisting mainly of cholesterol), fibrous material and calcium.
This forms an atheroma or plaque beneath the endothelium lining of the arteries.

5. Atheroma and Blood Pressure
As the atheroma grows the artery grows and thickens causing it to lose elasticity.
This results in a decrease in the diameter of the artery restricting blood flow and consequently an increase in blood pressure.

6. Contributing Factors to the Development of Atherosclerosis
High blood pressure
Carbon monoxide in cigarettes
Diabetes
High blood cholesterol levels

7. Atheromas form beneath the inner lining of the blood vessel
Larger atheroma's lead to -
Reduction in the diameter of the artery lumen
Restriction of blood flow to capillary bed served by the artery
An increase in blood pressure
Larger plaques may become hardened by calcium deposits and this causes arterial walls to become thicker and lose their elasticity – often called ‘hardening of the arteries’

8. Diseases caused by Atherosclerosis
Atherosclerosis is the root cause of various cardio vascular diseases (CVD) including:
Angina
Heart attack
Stroke
Peripheral vascular disease

9. Angina
Angina is caused by the coronary arteries becoming narrowed by atherosclerosis
It causes pains in the centre of the chest radiating out into the left arm and up into the neck and jaw

10. b - Thrombosis To be able to describe the process of thrombosis.
We will be learning…
To be able to describe the process of thrombosis.
To be able to explain the endothelium damage that occurs during atherosclerosis which results in a thrombus.
To explain the role that prothrombin, thrombin, fibrinogen and fibrin play in thrombosis
To explain thrombus formation and the effects of an embolus.
To be able to explain how thrombosis can lead to a myocardial infarction (MI).
To be able to explain how thrombosis in an artery in the brain can lead to a stroke.

11. Thrombosis
Thrombosis is the formation of a blood clot in a blood vessel of the heart. How does this happen?
As an atheroma becomes enlarged it may burst through the inner lining of the blood vessel and this ‘wound’ gets sealed by a blood clot, thrombosis
If the thrombosis breaks loose it is called an embolus
An embolus is carried along by the blood until it blocks a narrow blood vessel

12. Thrombosis

13. Clotting of Blood
In the presence of damaged cells, an inactive plasma enzyme called prothrombin becomes an active enzyme called thrombin Thrombin promotes the conversion of a soluble plasma protein called fibrinogen into insoluble fibrin threads – eventually becomes a blood clot Fibrinogen --- thrombin --- > Fibrin threads

14. Clotting of Blood
Clotting is the mechanism that prevents blood loss from broken blood vessels.
Platelets or damaged cells release a group of proteins called clotting factors. These clotting factors are released into the plasma at a wound site.
Clotting factors activate the enzyme Thrombin from its inactive form to prothrombin
Thrombin turns the soluble plasma protein fibrinogen into its insoluble fibrous form Fibrin.
The fibrin threads form a meshwork that clots the blood by binding platelets and blood cells to form a ‘plug’ (clot) to seal the wound and provide a scaffold for the formation of scar tissue

15. Sealing a Wound
Thrombin is responsible for causing molecules of fibrinogen (plasma proteins) to form threads of fibrin.
The threads form a meshwork that clots the blood, seals the wound and provides the scaffold for the formation of scar tissue
Fibrin threads
Red blood cells

16. Formation of a clot
The formation of a clot (thrombus) is known as thrombosis. The plaque from atherosclerosis provides a roughened surface that allows blood platelets to accumulate.
In some cases a thrombus may break loose forming an embolus and travel through the bloodstream until it blocks a blood vessel.
thrombus
embolus

17. If the thrombus breaks loose from the site of formation (embolus), it travels along the blood stream until it reaches an artery too narrow to allow it to get through.

18. Heart Attack (Myocardial Infarction)
If a thrombosis occurs in a coronary artery it may lead to a heart attack (myocardial infarction).
Heart attack or ‘coronary’ are common terms for the disorder myocardial infarction, which means, literally, death of part of the heart muscle following a blockage in its blood supply
Blocked coronary
artery
Dead heart muscle

19. Myocardial Infraction

20. Stroke
If a thrombosis occurs in an artery in the brain this may lead to a stroke.
When cells have been deprived of oxygen the tissue eventually dies.
Area of temporarily blocked blood flow
Blood clot in the middle cerebral artery
Blockage in the artery leading to the brain

21. c – Peripheral Vascular Disorders
We will be learning…
To be able to explain what is meant by peripheral vascular disorders.
To be able to describe deep vein thrombosis (DVT) as a blood clot that forms in a deep vein, most commonly in the leg.
To be able to describe how a clot can break off and result in a pulmonary embolism in the lungs.

22. Peripheral Vascular Disease
Peripheral arteries are arteries except the Aorta, Coronary and Carotid
Peripheral vascular disease is the narrowing of the arteries due to atherosclerosis in arteries other than those leading to the heart and brain.
The most commonly affected parts of the body are the legs.
Pain is experienced in the leg muscles due to a limited supply of oxygen.

23. Peripheral Vascular Disease
Caused by narrowing of the arteries other than those of the heart or brain
you may not know that you have the condition.
If you do get symptoms, the most common is pain or cramp in your calf (lower leg) or less commonly in your thigh, buttock muscles or feet.
The pain will come on after walking or doing other exercise as oxygen supply to the cells will be restricted. It will usually go away within a few minutes of you stopping the exercise.

24. Deep Vein Thrombosis (DVT)
A deep vein thrombosis is a blood clot that forms in a deep vein most commonly in the leg.
If the clot becomes loose and travels through the bloodstream it may result in a pulmonary embolism.

25. Pulmonary Embolism
A clot may block a small arterial branch of the Pulmonary Artery
This results in chest pain and breathing difficulties

26. d – Control of Cholesterol
We will be learning…
To be able to describe what cholesterol is and how its levels are controlled in the body.
To be able to state the uses that the body uses cholesterol for
To state the location of 25% of the production of cholesterol
To be able to describe the role that a diet high in saturated fats plays in causing an increase in cholesterol levels in the blood
To be able to describe the role of high density lipoproteins (HDL) and low density lipoproteins (LDL) by using the terms receptors, negative feedback control and atheroma formation.
To be able to explain how maintaining health is related to the ratios of HDL and LDL
To be able to describe the benefits of physical activity and a low fat diet on lowering cholesterol levels in the blood.
To be able to describe the how medicines such as statins can lower cholesterol levels in the blood.

27. Cholesterol Component of cell membrane Lipid 2 types of cholesterol
-carrying proteins (HDL, LDL)
Found in the diet –
Eggs, dairy, liver
HDL- carries %
Blood cholesterol
High levels lead to
development
of CVD
HDL- gathers
Cholesterol from body cells for
elimination by liver
Low-density
Lipoproteins (LDL)
- “bad cholesterol”
As level of HDL
Increases, risk of CHD
decreases
High-density
Lipoproteins (HDL)
- “good cholesterol”
LDL- carries up to 60-70%
Blood cholesterol from
liver to body cells
As level of LDL increases,
Level of CHD increases

28. What does the body need Cholesterol for?
Cholesterol is an important substance –
It is a precursor for the synthesis of steroids such as sex hormones
It is a basic component of cell membranes
Lipoproteins are present in the plasma and transport lipids around the body

29. Cholesterol
Cholesterol is an essential component of the body. It is required to build and maintain cell membranes.
Approximately 25% of cholesterol is produced in the liver and the rest is taken in as apart of our diet.
Cholesterol cannot travel around the body on its own because it does not dissolve in water. Instead, it is carried in the blood by molecules called lipoproteins.
The two main lipoproteins are LDL and HDL.

30. Low-density lipoprotein (LDL)
LDL is the main cholesterol transporter and carries cholesterol from your liver to the cells that need it.
If there is too much cholesterol for the cells to use, this can cause a harmful build-up in your blood.
Too much LDL cholesterol in the blood can cause cholesterol to build up in the artery walls (atherosclerosis), leading to disease of the arteries.

31. How do Cells Absorb Cholesterol?
Most cells make LDL receptors which become inserted in the cell membrane LDL carrying cholesterol (LDL-cholesterol) becomes attached to a receptor The cell then engulfs the LDL-cholesterol The cholesterol is released for use by the cell When the cell has enough cholesterol for its needs, the synthesis of new LDL receptors is inhbited

32. People who eat a diet rich in saturated fat, and People with an inherited condition called Familial Hypercholesterolaemia have LDL-cholesterol circulating in their bloodstream Cholesterol can become deposited in an atheroma in an artery wall LDL – cholesterol molecules are sometimes called ‘bad cholesterol’ (Another molecule, High-density lipoprotein- cholesterol is sometimes called ‘good cholesterol’)

33. High-density lipoprotein (HDL).
HDL carries cholesterol away from the cells and back to the liver, where it is either broken down or passed from the body as a waste product. This usually prevents a high level of cholesterol accumulating in the bloodstream
The amount of cholesterol in the blood (including both LDL and HDL) can be measured with a blood test.
Cholesterol is produced in the liver from fats and so foods which contain saturated fats will increase cholesterol.
Saturated fats can be replaced in many products by unsaturated fats such as olive oil e.g. animal fats to vegetable oils.

34. High-Density Lipoprotein
HDL-cholesterol is not taken into artery walls, therefore does not contribute to atherosclerosis These benefits depend on a ‘Healthy Balance’ between the LDL-cholesterol molecules and the HDL- cholesterol molecules

35. HDL to LDL Ratio
The higher the ratio of HDL to LDL is important for lowering blood cholesterol.
This in turn reduces the chance of atherosclerosis and maintains good health.
A higher HDL ratio can be achieved by increasing physical activity, eating a low fat diet (replacing saturated with unsaturated fats) and through prescribed medications.
E.g. statins reduce blood cholesterol by inhibiting the synthesis of cholesterol by liver cells.

36. Lowering Cholesterol Levels
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.

37. Statins
Drugs such as statins reduce cholesterol levels in the blood They inhibit an enzyme essential for the synthesis of cholesterol by liver cells
Molecules of LDL-cholesterol bind to LDL receptors on cell membranes
Sufferers of FH have a mutated gene that causes a decrease in the number of LDL receptors in the cell membrane
Molecules of LDL-cholesterol are unable to unload the cholesterol in cells
Sufferers have very high LDL-cholesterol in their bloodstream
If left untreated, large quantities of cholesterol are deposited in the walls of arteries
Statins work by inhibiting the enzyme needed for the synthesis of cholesterol by liver cells

38. Familial Hypercholesterolaemia
Familial hypercholesterolaemia is an inherited condition
The level of low-density lipoprotein (LDL) cholesterol in the blood is higher than normal from birth
It is caused by a defect in a gene which controls the way cholesterol is handled in the body
As a result of the defect, LDL receptor number is reduced or the structure altered. This stops the LDL from unloading its cholesterol into the cell. LDL cholesterol is not broken down properly and builds up in the bloodstream.
In most cases the defective gene is inherited from one parent (heterozygous inheritance, autosomal)
Results in the development of heart disease at a young age.
This is caused by plaques of atheroma developing within the walls of the coronary (heart) arteries

39. Treatment Eating healthily Getting a reasonable amount of exercise.
Avoiding smoking.
Maintaining a normal weight.
Use of statins

40. a – Process of Atherosclerosis
Now I can…..
Describe the process of atherosclerosis
State and explain its effect on arteries and blood pressure
Describe cardiovascular diseases (CVD) e.g. angina, heart attack, stroke and peripheral vascular disease.

41. b - Thrombosis Describe the process of thrombosis.
Now I can…
Describe the process of thrombosis.
Explain the endothelium damage that occurs during atherosclerosis which results in a thrombus.
Explain the role that prothrombin, thrombin, fibrinogen and fibrin play in thrombosis
Explain thrombus formation and the effects of an embolus.
Explain how thrombosis can lead to a myocardial infarction (MI).
Explain how thrombosis in an artery in the brain can lead to a stroke.

42. c – Peripheral Vascular Disorders
Now I can…
Explain what is meant by peripheral vascular disorders.
Describe deep vein thrombosis (DVT) as a blood clot that forms in a deep vein, most commonly in the leg.
Describe how a clot can break off and result in a pulmonary embolism in the lungs.

43. d – Control of Cholesterol
Now I can…
Describe what cholesterol is and how its levels are controlled in the body.
State the uses that the body uses cholesterol for
State the location of 25% of the production of cholesterol
Describe the role that a diet high in saturated fats plays in causing an increase in cholesterol levels in the blood
Describe the role of high density lipoproteins (HDL) and low density lipoproteins (LDL) by using the terms receptors, negative feedback control and atheroma formation.
Explain how maintaining health is related to the ratios of HDL and LDL
Describe the benefits of physical activity and a low fat diet on lowering cholesterol levels in the blood.
Describe the how medicines such as statins can lower cholesterol levels in the blood.

44. chest pain occurring when blood supply to heart muscle is restricted
Word
Meaning
Angina
chest pain occurring when blood supply to heart muscle is restricted
Atheroma
swelling on inner wall of artery made up of fatty material and connective tissue in time they become enlarged by the addition of fibrous materials, calcium and more cholesterol
Atherosclerosis
he formation of plaques, or atheroma's, beneath the inner lining in the wall of an artery
Cardiovascular diseases (CVD)
diseases affecting the heart and circulation
Cholesterol
lipid molecule needed for cell membranes and in synthesising steroid hormones
Deep vein thrombosis (DVT)
blood clot in a deep vein, often in the leg
Embolus
any detached mass of material carried by the circulation
Familial hypercholesterolaemia (FH)
inherited condition in which LDLs are at a higher than normal level in the blood
Fibrin
protein that helps form a blood clot

45. Section 15 Word Meaning Fibrogen
blood protein that is converted to fibrin during the blood clotting process
Heart attack
serious medical emergency in which blood supply to the heart muscle is blocked
High-density lipoprotein (HDL)
'good' cholesterol that transports fats away from cells and artery surfaces
LDL receptor
'receptor that recognises LDLs and encourages their uptake
Lipoprotein
assembly of protein with lipid that enables movement of lipid in water and through membranes
Low-density liproprotein (LDL)
'bad' cholesterol which is associated with high levels of atheroma's
Myocardial infarction (MI)
'medical term for a heart attack in which blood flow to the heart is reduced
Peripheral vascular disorder
condition caused by blockage to arteries other than coronary arteries, the aorta or those in the brain

46. Section 15 Word Meaning Prothrombin
blood component important in clotting; it is converted to thrombin during clotting
Pulmonary embolism
an embolism (blood clot) in the pulmonary circulation
Statin
a medicine that helps lower LDLs in the blood
Thrombin
produced from prothrombin during blood clotting
Thrombosis
blood clot within a blood vessel

47. Give an account of cholesterol in the body under the headings:
sources and removal of cholesterol; (3 marks)
high density lipoproteins and low density lipoproteins. (7 marks)

48. Sources and removal of cholesterol (maximum of 3 marks):
Cholesterol is formed in all body cells.
The liver is the greatest producer.
Cholesterol is present in animal foods e.g dairy products / meat / poultry / fish.
Cholesterol is eliminated from the body in the bile.
High density lipoproteins and low density lipoproteins (maximum of 7 marks):
Lipoproteins are made in the liver.
They are responsible for the transport of cholesterol.
High density lipoproteins (HDLs) carry cholesterol from the body cells to the liver.
Low density lipoproteins (LDLs) carry cholesterol from the liver to body cells.
LDLs attach to LDL-receptors on the cell membrane of most cells.
The production of LDL-receptors is controlled by negative feedback.
LDLs are carried into the cells to release their cholesterol.
Excess LDLs circulate in the blood and can become absorbed into the atheromas in plaques on artery walls.
A high ratio of HDLs to LDLs lowers the level of cholesterol in the blood…
…reducing the development of atherosclerosis

49. What is atherosclerosis?
2. Describe the composition of an atheroma
3. What is ‘hardening of the arteries’?
4. Name some problems associated with atherosclerosis
Atherosclerosis is the formation of plaques, or atheroma's, beneath the inner lining in the wall of an artery
Atheroma's are originally composed of fatty material, cholesterol, but in time they become enlarged by the addition of fibrous materials, calcium and more cholesterol
Larger plaques may become hardened by calcium deposits and this causes arterial walls to become thicker and lose their elasticity – often called ‘hardening of the arteries’
Coronary heart disease, Strokes, Heart attack, Peripheral vascular disease

50. 5. Explain how a thrombosis forms
If the thrombosis breaks loose it is called an embolus
An embolus is carried along by the blood until it blocks a narrow blood vessel
6. What is ‘Deep Vein Thrombosis’?
7. What is a ‘Pulmonary Embolism’?
As an atheroma becomes enlarged it may burst through the inner lining of the blood vessel and this ‘wound’ gets sealed by a blood clot, thrombosis
This is the formation of a thrombosis (blood clot) in a vein, commonly in the calf muscle of the lower leg
A clot may block a small arterial branch of the Pulmonary Artery, this results in chest pain and breathing difficulties

51. Suggested activities ?