5.2 Heart Disease Flashcards
What is Atheroma?
Atheroma is a fatty deposit that forms within the wall of an artery.
Which disease are about half of heart disease deaths due to?
Coronary heart disease (CHD)
How does Atheroma begin?
Atheroma begins as fatty steaks that are accumulations of white blood cells that have taken up low-density lipoproteins (LDLs).
In Atheroma, what do the fatty streaks develop into?
The streaks enlarge to form an irregular patch, or atheromatous plaque.
Atheromatous plaque most commonly occurs in large arteries and are made up of deposits of cholesterol, fibres and dead muscle cells.
How does Atheroma restrict blood flow and which two conditions do they increase the risk of?
The plaque bulges into the lumen of the artery.
They increase the risk of thrombosis and aneurysm.
Remember - plaques are formed…
WITHIN the artery wall. They are not deposits on the inner surface of the artery wall.
What is a thrombus?
If an Atheroma breaks through the lining of the blood vessel it forms a rough surface that interrupts the otherwise smooth flow of blood. This may result in the formation of a blood clot or thrombus - in the condition thrombosis.
How do thrombuses reduce blood supply?
The thrombus blocks the blood vessel, reducing or preventing supply of blood to tissues beyond it. This tissue will die. The thrombus is sometimes carried from its place of origin and loges in and blocks another artery.
What is an aneurysm?
Atheromas that lead to the formation of a thrombus weaken artery walls. These weakened points swell to form a ballon-like, blood-filled structure called an aneurysm.
Why are aneurysms dangerous?
Aneurysms frequently burst, leading to haemorrhage and therefore loss of blood to the region of the body served by that artery.
What is a brain aneurysm also known as?
A cerebrovascular accident (CVA) or stroke
What is the official name for a heart attack?
A myocardial infarction.
How does a myocardial infarction arise?
It results from the blockage of the coronary artery.
Why does the heart stop beating in myocardial infarction?
The blood supply to the cardiac muscle is completely cut off.
When are symptoms of myocardial infarction milder?
If the blockage is further along the coronary artery because a smaller area of muscle will suffer oxygen deprivation.
In Britain, how many people a year have a heart attack?
About half a million people but fewer than one third of them die as a result.
What are the risk factors associated with coronary heart disease?
Smoking
High blood pressure
Blood cholesterol
Diet
Name the two main constituents of tobacco smoke that increase the likelihood of heart disease.
Carbon monoxide
Nicotine
Describe the effects of carbon monoxide on oxygen supply.
Carbon monoxide combines irreversibly with haemoglobin in red blood cells to form carboxyhaemoglobin. It reduces the oxygen carrying ability of blood.
The tissues must work harder. This increases blood pressure and the risk of heart disease and strokes. During exercise the blood cannot supply the heart muscle with oxygen sufficiently. This leads to chest pain (angina) or myocardial infarction.
What effect does nicotine from tobacco smoke have on oxygen supply?
Nicotine stimulates the production of the hormone adrenaline, which increases heart rate and raises blood pressure. This leads to increased risk of smokers suffering coronary heart disease or a stroke.
Nicotine also makes the platelets in the blood more sticky which leads to higher risk of thrombosis.
How does high blood pressure increase the risk of heart disease?
- as there is already a higher pressure in the arteries, the heart must work harder to pump blood into them and is therefore more prone to failure
- higher blood pressure within the arteries means that they are more likely to develop an aneurysm and burst causing haemorrhage.
- to resist the higher pressure within them, the walls of the arteries tend to become thickened and may harden restricting blood flow.
Name the two types of cholesterol
High-density lipoproteins (HDLs)
Low-density lipoproteins (LDLs)
What is cholesterol an essential component of and how is it transported in the body?
Membranes. It is carried in the plasma as tiny spheres of lipoproteins (lipid and protein)
What is the role of HDLs?
They remove cholesterol from tissues and transport it to the liver for excretion. They help to protect arteries against heart disease.
