Blood vessels 3.2.2

Question 1

How many miles of blood vessels are there in the human body?

Answer 1

62,137 miles

Question 2

Name the 5 types of blood vessel

Answer 2

• Arteries
• Arterioles
• Capillaries
• Venules
• Veins

Question 3

What is the endothelium?

Answer 3

The inner layer or lining within blood vessels, which is very smooth to reduce friction with the flowing blood

Question 3

What is the function of arteries and arterioles?

Answer 3

They carry oxygenated blood AWAY from the heart, to the body under high pressure.
Arteries -> arterioles -> capillaries

Question 4

Name 4 features of arteries/arterioles

Answer 4

• Narrow lumen - maintains high pressure
• Inner layer (tunica intima) consists of thin elastic tissue which are made of elastin. These stretch and recoil.
• Thick elastic muscle fibres (middle layer - tunica media) which contracts and relaxes, changing the size of the lumen.
• Outer layer (tunica adventitia) is a relatively thick layer of collagen and elastic tissue. This provides strength to withstand high pressure

Question 5

Why do arterioles have more muscle than elastic fibres?

Answer 5

They constrict to increase resistance to flow and to reduce the rate of blood flow.
- They can divert the flow of blood to regions that require more oxygen

Question 6

What are capillaries?

Answer 6

The smallest blood vessels, which diffusion occurs in.

Question 7

Why are capillaries good for diffusion?

Answer 7

The walls are only one cell thick (7 micrometers lumen)

Question 8

What is the function of veins and venues?

Answer 8

They carry deoxygenated blood to the heart

Question 9

Name 4 features of veins and venues

Answer 9

• Have valves to prevent back flow
• Flow is assisted by the contraction of skeletal muscles
• Lumen is large to ease the flow of blood
• Have thinner layers of collagen, smooth muscle and elastic tissue and blood is carried at low pressures

Question 10

State 3 similarities of veins/venules and arteries/arterioles

Answer 10

• Collagen - makes them both strong and durable
• Elastic fibres for stretch and recoil
• Smooth muscle cells allow them to constrict and dilate

Question 11

State 4 differences between arteries/arterioles and veins/venules

Answer 11

Arteries:
- Narrow lumen
- Thicker walls - can withstand high pressure
- No valves
- More collagen, muscle, and elastic fibres
Veins:
- Wide lumen
- Thinner walls - under low pressure
- Valves
- Less collagen, muscle, and elastic fibres