1. Arteries, arterioles, capillaries, venules, veins
The Blood Vessels
Arteries, arterioles, capillaries, venules, veins

3. Structure of Arteries Four Layers: 1. Inner endothelium layer
2. Thick elastic connective tissue layer
3. Thick smooth muscle layer
4. Connective tissue layer

5. Arteries carry blood away from the heart
Elastic and muscular middle layers help arteries to keep blood flowing.
Steady pressure and flow is maintained through the arterioles

6. Blood pressure highest in the arteries Aorta is biggest in the body
Branches of aorta:
1 Coronary artery 2. Innominate arteries; subclavian branch,
carotid branches

8. Capillaries Microscopic vessels allowing exchange of materials
Vessel walls are one cell thick
One red blood cell fits inside diameter

9. Pressure inside capillaries causes fluid to leak into interstitial fluid
Capillaries are very numerous, no body cell is more than 100 micrometers from one

10. Structure of Veins Same layers as arteries but different proportions:
1. Inner endothelium layer
2. Thin elastic connective tissue layer
3. Thin smooth muscle layer
4. Connective tissue layer

11. Capillary blood drains into venules, which empty into veins
Veins carry blood back to the heart.
Pressure is lowest in the veins
Skeletal muscle help return blood to the heart
Veins have valves that prevent backflow

14. Varicose veins lose their ability to recoil and remain permanently swollen
Superior vena cava is the largest. It returns blood from the shoulders and head.
Inferior vena cava returns blood from the lower body