Blood Vessels

Question 1

What are the three blood vessels in the human body?

Answer 1

Artery
Vein
Capillary

Question 2

What are the properties of arteries?

Answer 2

• Small lumen so blood pumps at high pressure
• Has a thick wall of muscle
• Carries blood away from the heart

Question 3

What are the properties of veins?

Answer 3

• Has valves
• Carries blood towards the heart
• Large lumen so blood is at lower pressure
• Walls have thin muscle

Question 4

What are the properties of capillaries?

Answer 4

• Very small lumen
• Connects arteries and veins
• Walls are one cell thick
• Nutrients can diffuse in and out of the cells

Question 5

Why do veins have valves?

Answer 5

To prevent backflow of blood and ensure that it is only travelling in one direction (towards the heart)

Question 6

Why do arteries have a smaller lumen than veins?

Answer 6

To maintain the higher pressure of blood

Question 7

What does the blood transport?

Answer 7

Respiratory gases
Products of digestion
Metabolic waste
Hormones

Question 8

Where is everything transported in the blood (apart from oxygen)?

Answer 8

Plasma

Question 9

Why do multicellular organisms need specialised transport systems?

Answer 9

They have a low SA:V ratio
Therefore they need a specialised transport system to carry reactants from specialised exchange organs to their body cells

Question 10

Why is elastic tissue important in blood vessels?

Answer 10

Allows constant pressure of blood to be maintained
As the tissue is able to contract and relax

Question 11

Why is muscle tissue important in blood vessels?

Answer 11

Regulates the internal diameter of the muscle

Question 12

Why is epithelial tissue important in blood vessels?

Answer 12

Regulates substance exchange in and out of the bloodstream

Question 13

How are arteries structured?

Answer 13

• Walls are thick and muscular and have elastic tissue to stretch and recoil as the heart beats, which maintains high pressure
• The endothelium (inner lining) is folded, allowing the artery to stretch and maintain high pressure
• All arteries carry oxygenated blood apart from the pulmonary artery

Question 14

What are arterioles?

Answer 14

• Arteries divide into smaller vessels called arterioles
• These form a network throughout the body
• Blood is directed to different areas of demand by the muscles inside arterioles which constrict to restrict blood flow and relax to allow full blood flow

Question 15

How are veins structured?

Answer 15

• Wider lumen than arteries
• Very little muscle or elastic tissue
• Contains valves to prevent backflow
• Blow flow in veins is helped by the contraction of the body muscles surrounding them

Question 16

How are capillaries structured?

Answer 16

• Always found near cells in exchange tissue as there’s a short diffusion pathway
• Walls are only one cell thick so theres a short diffusion distance
• Rich capillary network, to increase surface area for exchange
• Aterioles branch into capillaries

Question 17

What are networks of capillaries in tissues called?

Answer 17

Capillary beds

Question 18

What do capillaries connect?

Answer 18

• Arterioles with venules
• Branch extensively to form capillary beds which permeate all parts of the body
• High hydrostatic pressure at arteriole end forces blood plasma out between endothelial cells
• This tissue fluid bathes the tissue cells