Topic 5: Atherosclerosis (Incomplete)

What is a cardiovascular disease?

What is a cardiovascular disease?

A cardiovascular disease is a disease of the heart and circulatory system, many of which are linked to atherosclerosis

What is a risk factor?

A risk factor is a factor that can be linked to an increased risk of a disease

• Many diseases are caused by the interaction of a number of factors

• Exposure to a risk factor doesn’t guarantee that an individual will suffer a disease

• Certain risk factors are correlated with certain diseases, but correlations are not always causations

Name four risk factors of cardiovascular diseases

1. Aspects of a person’s lifestyle such as the food they eat or whether or not they drink alcohol

2. Substances in a person’s body or environment such as air pollution in a crowded city or asbestos in old buildings

3. Genetic predispositions to developing certain diseases

4. Other biological factors such as age or biological sex

What is atherosclerosis?

Atherosclerosis, a hardening of the arteries, is a disease in which plaques (made of a yellowish fatty substance) build up on the inside of arteries.

• Plaques are most likely for form in the coronary arteries and carotid arteries (arteries in the neck)

• A plaque can continue to develop until it restricts the flow of blood through the artery or even blocks it out completely

• Atherosclerosis can begin in late childhood and continues throughout

  life.

What are the stages of the development of atherosclerosis?

1. Damage to the endothelium of the arteries

2. Inflammatory response

3. Accumulation of cholesterol

4. Formation of atheroma

5. Buildup of fibrous tissue/calcium salts

6. Plaque

7. Narrowing/loss of elasticity of the artery

How does atherosclerosis begin?

Atherosclerosis begins with damage to the endothelial lining of the blood vessels

• The damage cane caused by several factors

  • High blood pressure

  • Substances in tobacco smoke

Where does atherosclerosis usually occur and why?

Atherosclerosis usually occurs in the arteries rathe than the veins.

• This is because the blood in the arteries flow fast under relatively high pressure, which puts more strain on the endothelial lining of the vessels and can cause small areas of damage

• In the veins, the pressure is lower so damage to the endothelium is much less likely

What happens once damage to the endothelium has occurred?

Once damage to the endothelium has occurred, the body’s inflammatory response begins and white blood cells arrive at the site of the damage.

• The cells accumulate chemicals from the blood, especially cholesterol

• This leads to a plaque known as an atheroma form the endothelial lining of the artery

What causes the atheroma/plaque to harden?

The atheroma/plaque is hardened by fibrous tissue and calcium salts that build up around it

What is the consequences of plaque in the artery?

The plaque causes the lumen of the artery to narrow and become smaller and less ellastic

• This increases blood pressure, making it harder for the heart to pump blood around the body

  • Raised blood pressure makes damage more likely in other areas of the endothelial lining and more plaque will form

  • More plaques forming means that the blood pressure will get even higher, and the problem gets worse

Atherosclerosis can have serous effects on the health of an individual. What are three things that atherosclerosis can cause?

Atherosclerosis can cause:

1. Aneurysms

2. Angina

3. Myocardial infarctions

What is an aneurysm?

An aneurysm is a weakened bulging area of artery wall that results from blood collecting behind a blockage caused by plaques

How do aneurysms happen?

1. Blood tends to collect behind blockages caused by plaques that narrow arteries

2. The artery bulges and the wall is put under more pressure than usual, and becomes weakened

   • The weakened artery wall may split open, leading to massive internal bleeding

Where do aneurysms happen?

Aneurysms frequently happen

• In the blood vessels suppling the brain

• In the aorta, especially when it passes through the abdomen

Are aneurysms fatal?

Aneurysms are often fatal but if diagnosed can be treated by surgery before they burst

What causes high blood pressure?

High blood pressure is caused by arteries that have narrowed due to plaques in the walls

• This can lead to sever damage organs including the kidneys, he eyes and the brain

How does high blood pressure affect kidneys?

High blood pressure damages the tiny blood vessels where your kidney filters out urea and other substances from the blood

• If the vessels feeding the kidney tubules become narrow, the pressure inside them increases and proteins may be forced out their walls

If you have high blood pressure, how can kidney damage be identified?

If you have high blood pressure, kidney damage can be identified by a doctor by testing for protein in your urine

How can high blood pressure cause damage to your eyes?

High blood pressure can cause damage to the tiny blood vessels supplying the retina of your eye

• If the vessels become blocked or leak, the retinal cells are starved of oxygen and die and this can cause blindness.

What are the two most common types of heart disease?

1. Angina

2. Myocardial infarction (heart attack)

Both are closely linked to atherosclerosis

What is angina?

Angina is a condition in which plaques are deposited and build up on the endothelium of the arteries and reduce the blood flow of the cardiac muscle through the coronary artery

• It results in pain during exercise

When are symptoms of angina first noticed?

Symptoms of angina are first noticed during exercise, when when the cardiac muscle is working harder and needs more oxygen

• The narrowed coronary arteries cannot supply enough oxygenated blood

• The heart muscle resorts to anaerobic respiration

• This causes a gripping pain in the chest that can extend into the [left] arms and the jaw

  • It also causes breathlessness.

The symptoms subside once exercise stops

How can angina be helped?

Angina can be helped by:

1. Exercising regularly

2. Losing weight

3. Not smoking

How can the symptoms of angina be treated?

The symptoms of angina can be treated by drugs that cause rapid dilation of the coronary blood vessels so that they supply the cardiac muscle with the oxygen it needs.

What will happen if the blockage of the coronary arteries worsens?

If the blockage of the coronary arteries worsens, the symptoms of the angina will too

• Other drugs will then be used to dilate the blood vessels and reduce the heart rate.

• But drugs are not a permanent solution

What is a stent?

A stent is a a metal or plastic mesh tube that is inserted into an artery affected by atherosclerosis to hold it open and allow blood to pass through freely

What is a myocardial infarction (heart attack)?

A myocardial infarction (heart attack) the events which take place when atherosclerosis leads to the formation of a clot that blocks the coronary artery entirely and deprives the heart muscle of oxygen, so it dies; it can stop the heart functioning

What are most myocardial infarctions (heart attacks) caused by?

Many heart attacks are caused by a blood clot resulting from atherosclerosis

• The wall of an artery affected

  by a plaque is stiffened, making it much more likely to suffer damage.

• Platelets touch the damaged surface of the plaque and the clotting process is triggered

• The plaque itself may rupture and break open

  • The cholesterol that is released will also cause the platelets to trigger the blood clotting process.

What is a thrombosis?

A thrombosis a clot that forms in a blood vessel

What is the affect of a thrombosis (clot)?

A thrombosis (clot) can rapidly block the whole blood vessel, particularly it is already narrowed by a plaque.

What is a coronary thrombosis?

A coronary thrombosis is a thrombosis (clot) that gets stuck in a coronary artery

What causes a myocardial infarction (heart attack)?

A myocardial infarction (heart attack) is caused by a coronary thrombosis

• The coronary thrombosis can block the artery, starving the heart muscle of oxygen and nutrients leading to a heart attack

What occurs during a myocardial infarction (heart attack)?

During a myocardial infarction, there is severe chest pain that may occur at any time and it often lasts for several hours, although exercise may start it

• Death may occur very rapidly with no previous symptoms, or it may happen after several days of feeling tired and suffering symptoms mistaken for indigestion.

What should you do if you suspect that someone is suffering from a myocardial infarction

It is important to react quickly

1. Give them two full-strength aspirin tablets to help stop the blood clotting

2. Get them to hospital as fast as

   you can.

anaerobic respiration

anaerobic respiration cellular respiration that takes place in the

absence of oxygen

What is a stroke?

Stroke is an event caused by an interruption to the normal blood supply to an area of the brain

• Very often, the blood is cut off from one part or one side of the brain only

What is the stroke-causing interruption caused by?

The interruption may be due to bleeding from damaged capillaries or a blockage cutting off the blood supply to the brain, usually caused by a blood clot

• Sometimes, the blood clot forms somewhere else in the body and is carried in the bloodstream until it gets stuck in an artery in the brain.

What is a blockage usually caused by?

A blockage is usually caused by a blood clot, an atheroma or a combination of the two.

What can a blockage in one of the main arteries leading to the brain cause?

A blockage in one of the main arteries leading to the brain causes a very serious stroke that may lead to death.

What are the symptoms of a stroke?

1. Dizziness

2. Confusion

3. Slurred speech

4. Blurred vision or partial loss of vision

   (usually one eye)

5. Numbness.

What is a symptom of more sever strokes?

In more severe strokes, there can be paralysis, usually on one side of the body.

What does the outcome of a myocardial infarction or stroke depends on?

The outcome of a myocardial infarction or stroke depends on how soon the patient is treated

• The sooner the patient is given

  treatment, including clot-busting drugs that break down or dissolve the blood clot, the more likely they are to survive.

Name four medications/treatments for cadiovasuclar diseases

1. Antihypertensives

2. Statins

3. Anticoagulants

4. Platelet inhibitors

When a plaque starts to form on the endothelium (lining) of an artery, it usually gets worse and worse. Unless the person changes their lifestyle or gets medical treatment, the lining of the artery does not return to normal. Explain why this happens, and why it is so dangerous.

• Plaque formation can be caused by damage to the endothelial lining of an artery.

• This increases blood pressure making further damage more likely, so more plaques form, and so on.

• Increased blood pressure can result in many problems in the kidneys, eyes and brain, as well as aneurysms.

• Decreased blood flow through arteries partly blocked with plaques is dangerous in the coronary arteries and in the brain where it may cause damage to tissue beyond the blockage.

• Clots may form, causing complete blockage of the blood vessel, which can be catastrophic.

Describe the role of atherosclerosis in cardiovascular disease.

Atherosclerosis increases the risk of cardiovascular disease in many ways:

1. Atherosclerosis narrows and/or stiffens the blood vessels, raising blood pressure.

   • Raised blood pressure can damage small capillaries and increases the risk of damage to the endothelial lining.

2. Damage to the endothelial lining or an atheroma itself can attract platelets that can trigger the clotting mechanisms,

   • Including the release of thromboplastin, which catalyses the formation of thrombin from prothrombin, which then catalyses the formation of fibrin from fibrinogen in the blood.

   • The fibrin produces a mesh that traps red blood cells and forms a clot.

   • The clot may then block a blood vessel causing a thrombosis.

   • In a coronary artery, this can lead to a heart attack; in the brain, this may cause a stroke.

Summarise the similarities and differences between a heart attack and a stroke.

Similarities:

1. Both may be caused by a blood clot (thrombosis) or the formation of an atheroma, or a combination of both

2. Both may be fatal or cause long-term damage to health.

Differences

1. Heart attack produces chest pain and may be triggered by exercise

2. Stroke may affect many parts of the body through the damage caused to the brain and may also be caused by bleeding in the brain after an aneurysm bursts.