CB8.2The circulatory system: heart structure and function, blood vessels (arteries, veins, capillaries), blood components and their roles

Notes

Humans have a double circulatory system:

Advantage: blood is re-oxygenated and repressurised between circuits → efficient delivery to body tissues.

Right atrium → receives deoxygenated blood from body.
Right ventricle → pumps blood to lungs.
Left atrium → receives oxygenated blood from lungs.
Left ventricle → pumps blood to body (thickest wall — high pressure needed).
Valves (atrioventricular and semilunar) → prevent backflow.

Coronary arteries supply the heart muscle itself with oxygenated blood.

Vessel	Wall	Lumen	Function
Artery	Thick, elastic, muscular	Narrow	Carry blood away from heart at high pressure
Vein	Thin wall	Wide	Return blood to heart at low pressure; have valves
Capillary	One cell thick	Tiny	Exchange of substances with tissues

Component	Function
Red blood cells	Carry oxygen (haemoglobin)
White blood cells	Immune response (phagocytes, lymphocytes)
Platelets	Blood clotting
Plasma	Carries dissolved substances (glucose, CO₂, urea, hormones)

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Question 13 marks
Double circulation — advantage
(3 marks) Explain one advantage of the double circulatory system over a single circulatory system.
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Question 24 marks
Blood vessel comparison
(4 marks) Compare the structure of arteries and veins. Give two structural differences and relate each to function.
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Question 34 marks
Blood components
(4 marks) Name the blood component responsible for each function:

(a) Carrying oxygen from the lungs to the body. (1 mark)
(b) Engulfing and destroying bacteria. (1 mark)
(c) Carrying dissolved glucose to cells. (1 mark)
(d) Forming a clot at the site of a wound. (1 mark)
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CB8.2 — The circulatory system: heart, blood vessels and blood

6-card SR deck for Edexcel Combined Science topic CB8.2

6 cards · spaced repetition (SM-2)