Blood Vessels

Question 1

Lumen

Answer 1

Cavity through which blood flows

Question 2

3 Layers in wall of arteries and veins

Answer 2

1) Tunica intima/ interna
2) Tunica media
3) Tunica externa

Question 3

Tunica interna

Answer 3

• Surrounds single innermost layer of endothelium (1 cell thick)
• (Endothelium) smooth lining to reduce friction and minimise resistance

Question 4

Tunica Media

Answer 4

• Smooth muscle to contract and constrict vessel to regulate blood flow
• Elastic fibres to stretch and recoil, which stretch to sustain blood pressure
• Thicker in arteries- higher pressure

Question 5

Tunica externa

Answer 5

• Made of collagen = strong fibrous protein

- Withstand pressure and prevent overstretching

Question 6

Capillaries

Answer 6

• 1 cell thick and forms network that connects small arteries and veins
• Thin walls = short diffusion distance
• Narrow lumen- slows down blood flow so higher time for exchange
• Small gaps between endothelium = permeable to solutes

Question 7

Arteries

Answer 7

Carry high pressure blood away from heart

• Narrow lumen to maintain high pressure
• No valves
• More elastic tissue in walls to maintain high pressure via elastic recoil
• Thicker muscle wall
• Smooth muscles in arterioles to regulate blood flow and adjust diameter

Question 8

Veins

Answer 8

Return low pressure blood back to the heart

• Larger lumen to reduce friction/ resistance
• Valves to prevent backflow of blood
• Thinner muscle layer and walls as blood at lower pressure
• Smooth endothelium lining = less friction
• Skeletal muscle contracts to return blood to heart