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MyGCSEScience · AQA Biology
The Circulatory System
Heart structure · Double circulation · Blood vessels · Opens in MyGCSEScience
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MyGCSEScience · AQA Biology
Cardiovascular Disease
Coronary heart disease · Stents · Statins · Useful context for B2.4 too
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Key facts to know
Heart structure
- Four chambers: left atrium, left ventricle, right atrium, right ventricle
- Valves prevent backflow of blood
- Left ventricle has thicker walls — pumps blood to the whole body
- Right ventricle pumps blood only to the lungs (shorter distance)
- Coronary arteries supply the heart muscle itself with blood
- The heart is a double pump — right side pumps to lungs, left side pumps to body
Blood vessels — three types
- Arteries: thick muscular walls, narrow lumen, high pressure, carry blood away from heart, no valves
- Veins: thinner walls, wider lumen, low pressure, carry blood to heart, have valves
- Capillaries: one cell thick wall, very narrow, allow exchange of substances with cells
- Memory: Artery → Away from heart
Double circulation — the two circuits
- Pulmonary circuit: right side of heart → lungs → left side of heart (picks up oxygen, loses CO₂)
- Systemic circuit: left side of heart → body → right side of heart (delivers oxygen, picks up CO₂)
- Blood travels through the heart twice for each complete circuit of the body
- Advantage: maintains high pressure for delivery to body organs
Exam questions — 7 questions · 12 marks total
1 mark
Blood vessels
AQA Jun 2024 P1 Q1.1
A patient has a blocked coronary artery. The blood vessel that carries blood away from the heart at high pressure is called a/an:
A Vein
B Capillary
C Artery
D Alveolus
1 mark
Heart function
AQA Jun 2024 P1 Q1.2
Explain why the heart needs to pump blood around the body. (1 mark)
A To digest food in the stomach
B To move blood and get oxygen to cells around the body
C To remove blood from the lungs
D To produce red blood cells
1 mark
Heart chambers
AQA Jun 2023 P1 Q2.3
Blood returning from the lungs enters which chamber of the heart first?
A Right atrium
B Left atrium
C Left ventricle
D Right ventricle
2 marks
Arteries vs veins
AQA Jun 2023 P1 Q2.4
Give two ways in which the structure of an artery differs from the structure of a vein. (2 marks)
+20 XP
2 marks
Double circulation
AQA specification style
Describe what is meant by double circulation in humans. (2 marks)
+20 XP
1 mark
Stents
AQA Jun 2024 P1 Q1.5
A stent is inserted into a blocked coronary artery. What does a stent do?
A Reduces cholesterol levels in the blood
B Dissolves the fatty deposit blocking the vessel
C Opens and holds open the blocked blood vessel so blood can flow
D Replaces the damaged section of artery with an artificial vessel
4 marks
Heart structure & function
AQA specification style — extended answer
Explain why the left ventricle has a thicker muscular wall than the right ventricle. Use your knowledge of circulation in your answer. (4 marks)
+40 XP
Module complete! 🎉
You scored — on this attempt.