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Higher Human Biology
Unit 2
Physiology & Health
KEY AREA 7: Pathology of Cardiovascular Disease (CVD)
Higher Human Biology
We are going to build on the knowledge and skills that you developed during N5 and will
learn about the following Physiology & Health key areas : -
Key Area 1 – Reproductive Organs
Key Area 2 –Hormonal Control of Reproduction
Key Area 3 – Biology of Controlling Fertility
Key Area 4 – Ante- and Postnatal Screening
Key Area 5 – Structure and Function of Arteries, Capillaries and Veins
Key Area 6 – Structure and Function of the heart
Key Area 7 – Pathology of Cardiovascular Disease (CVD)
Key Area 8 – Blood Glucose Levels and Obesity
Physiology & Health Learning Intentions
KEY AREA 7– Pathology of Cardio Vascular Disease (CVD)
a) Process of Atherosclerosis
b) Thrombosis
c) Causes of Peripheral Vascular Disorders
d) Control of Cholesterol levels and familial hypercholesterolemia
7a) Atherosclerosis
Atherosclerosis is the formation of plaques called
atheromas under the endothelium in the wall of an artery
Initially plaques are formed of fatty materials (consisting
mainly of cholesterol), but as years increase, the plaques
become enlarged as fibrous material, calcium and more
cholesterol are added - making larger atheromas
Large atheromas lead to:Decreased diameter of the artery’s lumen
Restriction of blood flow to the capillary bed
An increase in blood pressure
Hardening of the arteries (artery walls lose elasticity
due to deposits of calcium)
Various Cardiovascular diseases e.g.
Coronary Heart Disease (including angina)
Strokes
Heart Attacks (myocardial infarctions)
Peripheral vascular disease
7b) Blood Clotting
Blood clotting is a protective device to prevent loss of blood at a wound e.g. when
Atheroma's rupture they damage the endothelium cells.
The presence of damaged cells leads to the release of blood clotting factors that change
the inactive enzyme prothrombin into its active form thrombin
Fibrinogen
(a soluble plasma protein)
Thrombin

Threads of fibrin
(an insoluble protein)
Fibrin threads a meshwork that clots the blood, seals the wound and provides a scaffold
for the formation of scar tissue
The formation of a blood clot (thrombus) is called thrombosis
7c) Thrombosis
Atheromas on the inside lining of an artery
can damage the endothelium leading to the
formation of a thrombus.
If the thrombus breaks loose, it is called an
embolus
An embolus is carried along by blood until it
blocks a narrow vessel and restricts or blocks
block flow
If an embolus blocks a coronary artery, it’s
called coronary thrombosis, and the heart
muscle can be starved of oxygen and may lead
to myocardial infarction (heart attack)
A thrombus that causes a blockage in an
artery to the brain may lead to a stoke
7d) Causes of peripheral vascular disorders
The peripheral arteries are those other than the aorta, coronary and carotid
arteries
Peripheral vascular disease is the narrowing of the arteries(other than those
of the heart and brain) due to atherosclerosis
Peripheral vascular disease mostly affects leg arteries.
Blood flow to the legs is restricted and pain is felt due to lack of oxygen
Deep Vein Thrombosis (DVT) is the formation of a thrombus (blood clot) in a
vein (most commonly in the lower leg). This causes the area to be painful,
swell up and veins close to the skin surface can become engorged with blood.
If an embolus blocks a pulmonary artery it leads
to the serious situation called a pulmonary embolism
and the person experiences
chest pains, breathing difficulties and palpitations
7e) Cholesterol levels
Lipids are a diverse group of organic compounds which include simple lipids
(e.g. fats) and more complex lipids (e.g. steroids)
Cholesterol is important because it is needed for the synthesis of steroids
(e.g. sex hormones) and is a basic component of cell membranes
The presence of cholesterol at a specific concentration in the bloodstream is
essential to the health and well-being of the human body
Cholesterol is produced in the liver cells from saturated fats present in a
normal balanced diet
Lipoproteins are molecules containing a combination of lipid and protein, and
are found in blood plasma which transports the lipids from one part of the
body to another
7f) Low-density Lipoproteins (LDL)
Low-density lipoproteins (LDL) are produced by the liver
Most body cells synthesise LDL receptors which then embed in their cell
membrane.
When a molecule of LDL carrying LDL-cholesterol becomes attached to the
receptor, the cell engulfs the LDL-cholesterol and the cholesterol is released
for use by the cell
When the body cell contains an adequate supply of cholesterol, a negative
feedback system is triggered which inhibits the synthesis of new LDL
receptors. Therefore less LDL-cholesterol in the blood is absorbed by body
cells.
Some of the excess cholesterol is taken up by endothelial cells lining the
inside of an artery, and is deposited in an atheroma. This will happen to people
that eat a diet rich in saturated fats, and/or suffer from
hypercholesterolemia (see later slides)
7g) Control of cholesterol levels
7h) Excess Cholesterol
Some of the excess cholesterol is taken up by endothelial cells lining the
inside of an artery, and is deposited in an atheroma.
This will happen to people that:Eat a diet rich in saturated fats
and/or
Suffer from Hypercholesterolemia (see later slides)
7i) High-density lipoproteins (HDL)
Some of the excess cholesterol is transported by High-density
lipoproteins (HDL) from body cells to the liver for elimination – which
prevents a high level of cholesterol accumulating in the bloodstream
Also, HDL-cholesterol is not taken into artery walls so does not
contribute to atherosclerosis
The healthy balance of HDL-cholesterol and LDL-cholesterol molecules
is essential to ensure excess cholesterol is not in the bloodstream
Normally, HDL molecules carries about 30% of blood cholesterol, and
LDL molecules carry about 70%.
If there is a higher ratio of HDL to LDL, there will be a decrease in
blood cholesterol, thus decreasing the chances of atherosclerosis and
CVD
7j) Familial Hypercholesterolemia (FH)
Familial hypercholesterolemia (FH) is an inherited disorder that shows an
autosomal dominant gene that predisposes individuals to developing high levels
of cholesterol.
In FH sufferers the mutated gene causes a decrease in the number of LDL
receptors present in the cell membranes, or a change in their structure that
renders then non-functional.
FH sufferers have a VERY high-LDL-cholesterol levels
If left untreated, FH sufferers will have CV problems at a much younger age
than others in the population
People whose family has a history of FH can take a genetic test to determine if
they have inherited an FH allele
FH can be treated by modifying life style choices and taking drugs such as
statins
7k) Statins
Regular exercise causes people to have higher concentrations of HDLcholesterol
Low fat diets cause people to have higher concentration of HDL-cholesterol
Drugs called Statins lower cholesterol in the blood by inhibiting the enzyme
essential for the synthesis of cholesterol by liver cells
Physiology & Health Questions
KEY AREA 7 – Pathology of CVD
1. Testing Your Knowledge 1
2.
Quick Quiz
Page
186
Q’s 1-4