IGCSE · Practice questions · Blood vessels

Shaped by the pressure inside.

Six original Cambridge-style questions comparing arteries, veins and capillaries, linking their structure to pressure and function, and naming the main blood vessels.

Original questions All questions on this page are original work, written in the Cambridge IGCSE style. They are not from past papers. They test the same concepts and skills the syllabus rewards.

Keep these straight

Direction, not colour.

Arteries: away from the heart; thick muscular, elastic wall; narrow lumen; high pressure.
Veins: back to the heart; thin wall; wide lumen; valves; low pressure.
Capillaries: wall one cell thick; exchange with the tissues.
Organ vessels: pulmonary (lungs), renal (kidneys), hepatic (liver, Extended); the hepatic portal vein comes from the gut.

Recall

[3 marks]

Describe three differences between the structure of an artery and a vein.

Arteries have a thicker wall than veins. ✓
Arteries have a narrower lumen than veins (relative to the vessel size). ✓
Veins have valves; arteries do not (apart from where they leave the heart). (Also accept: arteries have more muscle and elastic tissue.) ✓

Recall

[2 marks]

State the functions of capillaries.

They carry blood close to every cell of the tissues. ✓
They are where substances are exchanged between blood and cells: oxygen and glucose move out to the cells, carbon dioxide and urea move into the blood. ✓

Explain

[4 marks]

Extended. Explain how the structure of arteries and veins is related to the pressure of the blood they carry.

Arteries carry blood at high pressure, straight from the heart, so they need a thick wall to withstand the pressure without bursting. ✓
Elastic tissue in the artery wall stretches and recoils with each heartbeat, smoothing the flow; muscle and a narrow lumen keep the pressure high. ✓
Veins carry blood at low pressure, so their walls can be thin; the wide lumen gives little resistance to flow. ✓
Because the pressure is low, valves are needed in veins to prevent blood flowing backwards. ✓

Explain

[4 marks]

Extended. Explain how the structure of capillaries is related to their function.

The wall is one cell thick, giving a short diffusion distance between blood and cells. ✓
The wall is permeable, so substances such as glucose, oxygen and urea can pass through. ✓
Capillaries are very narrow and highly branched, so every cell is close to one and there is a large total surface area for exchange. ✓
Blood flows slowly and red blood cells pass in single file, giving time for exchange. ✓

Data

[4 marks]

The table shows the mean blood pressure in different vessels.

Vessel	Mean pressure / kPa
aorta	13.0
small artery	11.5
capillary	3.5
small vein	1.6
vena cava	0.5

(a) Describe the trend shown. (b) Between which two vessels is the largest fall in pressure? (c) Use the data to explain why veins have valves.

(a) The pressure falls continuously as blood moves from the aorta, through the arteries and capillaries, to the veins and vena cava. ✓
(b) Between the small artery and the capillary (a fall of 8.0 kPa). ✓
(c) In the veins the pressure is very low (1.6 to 0.5 kPa), too low to keep the blood moving reliably towards the heart. ✓
Valves close if blood starts to flow backwards, so blood only moves towards the heart. ✓

Recall

[4 marks]

Name the blood vessel that (a) carries blood from the lungs to the heart, (b) carries blood from the kidney, (c) carries blood from the aorta to the kidney, (d) (Extended) carries blood from the liver towards the heart.

(a) pulmonary vein. ✓
(b) renal vein. ✓
(c) renal artery. ✓
(d) hepatic vein. ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.