Circultory System: Blood Vessels

Question 1

Arteries

Answer 1

Carry blood away from heart
- higher pressure
- no valves
- tunica media more prominent

Question 2

Veins

Answer 2

Carry blood back to heart
- lower pressure
- valves
- less prominent tunica media

Question 3

Capillaries

Answer 3

Connects smallest arteries to smallest veins, creating a circuit

Question 4

3 layers of artery/vein walls

Answer 4

1. Tunica interna
2. Tunica media
3. Tunica externa

Question 5

Tunica interna (tunica intima)

Answer 5

• lines blood vessels and is exposed to blood
  Endothelium: simple squamous epithelium
• selectively permeable barrier
• secretes chemicals that stimulate dilation/constriction
• repels blood cells/platelets to prevent clotting
• when tissue around vessel is inflamed, endothelial cells produce cell adhesion molecules —> leukocytes then adhere to surface and congregate in tissues where their defensive actions are needed

Question 6

Tunica media

Answer 6

Middle layer
- smooth muscle, collagen, elastic fiber
- strengthens vessels and prevents blood pressure from rupturing them
- contraction of muscle controls blood vessel diameter
- more prominent in arteries than veins

Question 7

Tunica externa (tunica aventititia)

Answer 7

Outermost layer
- loose connective tissue that merges with neighbouring vessel

Question 8

Vasa vasorum

Answer 8

Part of tunica externa
Small vessels that supply blood to outer part of the larger vessels (arteries and veins)