TOPIC 2: Blood Vessels & Atherosclerosis

What is the role of the arteries?

Carry oxygenated blood away from the heart to the rest of the body

What is the role of the capillaries?

Smallest blood vessels which are responsible for exchanging substances between the blood and the cells by diffusion.

What is the role of the veins?

Carry deoxygenated blood from the body into the heart.

What is the role of the PULMONARY arteries? (exception to rule)

Carry deoxygenated blood from the heart to the lungs for oxygenation

What is the role of the PULMONARY veins? (exception to rule)

Carry oxygenated blood to the heart from the lungs

State the structure and function of the artery.

- Thick collagen wall= Thick to provide strength to the artery as well as to withstand high blood pressure.

- Smooth muscle= Stretches and recoils to maintain high blood pressure.

-Elastic tissue=Contracts to withstand the high blood pressure. Smooth lining reduces friction.

-Narrow lumen=Narrow to maintain high blood pressure.

State the structure and function of the vein.

-Low blood pressure

-Valves= to prevent back flow of blood

-Wide lumen= to reduce blood pressure

-Thin smooth muscle & elastic layer= veins do not need to stretch and recoil

State the structure and function of capillary.

-Low blood pressure

-Narrow lumen

-Wall consists of a single layer of epithelial cells with tiny pores in between=to allow diffusion of substances.

What is atherosclerosis?

A form of cardiovascular disease. It occurs when fatty deposits up in the arteries.

What lifestyle factors can lead to atherosclerosis?

• High cholesterol

• Obesity

• High fat diet

• Plaques

Formula for Body Mass Index (BMI)?

weight (kg)
height²(m)

What are the ways to calculate whether someone is obese?

• Calculate BMI

• Calculate waist to hip ratio

What is meant by cardiovascular disease?

Conditions affecting the heart and blood.

What is the function of a lipoprotein?

Biological molecules that transport cholesterol around the body.

What are the two types of lipoproteins?

• HDLs (high density lipoproteins): transport cholesterol to the liver where it is broken down. GOOD

• LDLs (low density lipoproteins): transport cholesterol to cells BAD

Which protein increases cholesterol in the blood?

LDLs increase blood cholesterol= transports cholesterol to cells= if cells are overloaded, LDLs remain in the blood

What is the impact of too much cholesterol in the blood?

Atherosclerosis

What is atherosclerosis?

Fatty deposits that form on the endothelial lining of arteries

What structural consequences arise from atherosclerotic plaques formation on the endothelial lining of the arteries?

• Narrows the lumen

• Loss of elasticity of the artery

What is the impact of atherosclerosis on blood pressure in the arteries?

Blocks the lumen of the artery wall → restricts blood flow → BP increases

What does self-perpetuating mean?

Makes itself continue indefinetly

Why is Atherosclerosis self-perpetuating?

• Plaque formation causes high blood pressure

• HIGH BP causes further damage to endothelium
  → Causing further atheroma

Explain the formation of atherosclerotic plaques?

1. Slight damage occurs to the endothelial cells in the lining of the artery → caused by high blood pressure

2. White blood cells accumulate at the site of damage & trigger a local inflammatory response.
   Cholesterol builds up in the area → formation of a fatty plaque

3. Calcium salts build up around the atheroma, turning it into a hardened plaque
   The artery wall begins to harden & become less elastic

4. The size of the lumen becomes very narrow → severely restricts blood flow → increases BP

Explain the consequences of atheroma formation/ partial blockage?

1. Atheroma/ plaque restricts blood flow downstream in the artery due to narrowing the size of the lumen.

2. Less blood flows to the cells & tissues further downstream.

3. Less glucose & oxygen are delivered to respiring cells.

4. Cells will start to respire anaerobically and lactic acid will build up in the tissues.

What is angina?

When atheroma builds up on the walls of the coronary arteries

What are the symptoms of someone suffering from angina?

Chest pain due to a build up of lactic acid

Suggest a reason for the symptoms associated with angina?

• Fatty deposits/ plaques/ cholesterol/ atheroma narrows/ blocks arteries

—> Less blood flows to cardiac muscles/ tissues through coronary artery.

What do antihypertensive drugs do?

Reduces blood pressure

-→ Which reduces the risk of endothelial damage to the artery lining.

-→ This means they lower the risk of atheroma formation.

What do calcium channel blockers do?

• Block calcium ion channels in the muscle cells of the arteries → preventing them from contracting

• Lower blood pressure & reduces plaque formation

What are the risks of calcium channel blockers?

• Headaches

• Dizziness

• Constipation

• Swelling of ankles

• Abnormal heart rhythms

What do diuretics do?

• Increase the volume of urine produced by the kidneys and get rid of excess fluids and salt

• Reduces plaque formation

What are the risks of diuretics?

• Dizziness

• Nausea

• Muscle cramps

What do ACE Inhibitors do?

• Prevent the formation of a angiotensin a hormone, which causes vasoconstriction of the blood vessels.

What are the risks of ACE Inhibitors?

• Dry cough

• Dizziness

• Abnormal heart rhythm

• Reduced kidney function

What do beta blockers do?

• Reduce the heart rate & force of muscular contraction of the heart rate

What are the risks of beta blockers?

• Dizziness

• Tiredness

• Nausea