Blood Vessels

Artery:

Contains:

• Endothelium intima
• Thick Tunica Media (with smooth muscle and elastic fibres), to deal with the high pressure blood and allows the arteries to recoil
• Has a relatively thick tunica externa
• Relatively smaller lumen
• Has high pressure pulsitile blood

Function=To carry high pressure blood away from the heart 

Capillary:

Contains:

• Endothelium made up of 1 layer thick squamous epithelium (thin walls)
• 1 RBC thick lumen
• Average blood pressure

Function=Exchange vessel to the organs

Vein:

Contains:

• Endothelium intima
• Relatively thinner Tunica media
• Thinner tunica externa
• Valves, prevent the backflow of blood aiding its return (if valves fail to close then it can result in varicose veins or the build up of blood)
• Very large lumen
• Very low blood pressure

Function=Carry blood to the heart

Arterioles:

Function=Are able to contract forcing blood to go through a seperate tube straight into the venules. Also connect the arteries to the capillaries.

Venules:

Function=Connects veins to the capillaries