1. 6.2.5 Explain the relationship between the structure and function of arteries, capillaries and veins Mathilde Xiao and Liam Kennedy

2. http://www.youtube.com/watch?v=3Q5x0znIFnI

3. Structure of the Artery Arteries Fairly narrow lumen (blood at higher pressure) No valves apart from the semi lunar valves. Thick tunica media, with muscle and elastin fibres Thick outer layer of collagen (withstand high pressure)

4. Functions of the Arteries Withstand high blood pressures without the artery wall bulging outwards (aneurysm) or bursting (haemorrhage) Accommodate large volumes of blood pumped out by the ventricles of the heart and then pump it on to capillary networks

5. Structure of the Vein Veins Larger lumen than the arteries (blood travels at lower pressure) Thin outer layer (pressure low & allows nearby muscles to push blood) Thin circular layer (blood not in pulses) Have valves (prevents blood pooling at lower extremities as well as backflow)

6. Functions of the Veins Transport of blood, without leaks, from capillary networks to the atria of the heart Prevention of backflow when blood pressure or flow rate is low Flexibility to be squeezed by adjacent muscles to help pump blood

7. Structure of the Capillary Capillaries Wall is fenestrated and one cell thick (allows for diffusion) Very narrow lumen (single file blood cells increase exchange of materials)

8. Functions of the Capillaries Transport blood as close as possible to all living cells of the body Allow the substances that blood is transporting to enter and leave rapidly Allow part of the blood plasma to leak out into tissues but not proteins or blood cells

9. Blood Vessel Disease Blood vessel diseases are caused by the narrowing down or constriction of blood vessels This constriction is composed of plaque built from fat over long periods of time Diet, gender, age and genetics can be factors that cause blood vessel diseases

10. Different types of blood vessel diseases: -Coronary Artery Disease -Aneurysm -Peripheral Arterial Disease -Hypertension

11. Symptoms Muscle cramps/ache Cold hands and feet Pale skin Hair loss on the toes, feet and legs Sores that take too long to heal Sores when scabbed over appear black Slight or no pulse in the feet or legs Skin and nails appear reddish-blue in color