Blood Vessels

3 types of blood vessels

Arteries: take away blood from the heart (high pressure blood, contains a plentiful supply of oxygen & haemoglobin)
Veins: take blood to the heart (lower pressure and contains less oxygen)
Capillaries: tiny blood vessels (take blood to and from cells)

Structure of arteries, veins & capillaries

arteries and veins have an outer layer of elastic and connective tissue
thicker connective outer layer of tissue in veins to prevent collapsing- veins are likelier to collapse due to a lower pressure of blood
arteries and veins contain an outer layer of smooth muscle tissue
arteries have a thicker outer layer of smooth muscle- helps to pump the blood around the body to maintain the pressure
capillaries, veins and arteries all contain an endothelial layer
arteries and veins contain their endothelial layer on the inside of their structure

Atherosclerosis

fatty deposits (atheroma) can block an artery or cause blood clotting blocking the artery (thrombosis)
artery becomes narrow, less elastic- causing restricted blood flow and an increased chance of blood clotting
blood pressure rises- damages the endothelial tissue lining further

could lead to coronary disease (e.g heart attacks) and strokes (if an artery going to the brain is blocked)

Causes of atherosclerosis

endothelial tissue lining is damaged (e.g by smoking or high blood pressure)
LDL cholesterol (low density lipoproteins) accumulates in the artery wall- causing inflammation & white blood cells to move towards the artery wall
the results of the build up (LDL cholesterol, fibres, calcium salts & white blood cells) causes plaque formation (atheroma) and blocks the artery

Cigarette fumes