B5.2B5. Transport in Humans

Heart — Combined Science 0653 - Biology Revision Notes & Topical Questions

10 min read 27 parts Lesson 3 of 15 1 quiz

📚 Combined Science 0653 - Biology Hub / Topical Revision

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Lesson summary

B5.2 Heart — COMBINED SCIENCE notes: Describe the structure of the mammalian heart and the route of blood through it.Diagram — the heart is labelled as if it were in the chest, so the left of the diagram is the right side of the body.Right side — receives deoxygenated blood from …

Memory aid
Ventricles
Left ventricle
Right ventricle
Cardiac muscle
Coronary arteries

Part 1 of 9Heart sides and diagram orientation

Diagram

Diagram the heart is labelled as if it were in the chest, so the left of the diagram is the right side of the body.

Right side

Right side receives deoxygenated blood from the body and pumps it to the lungs.

Left side

Left side receives oxygenated blood from the lungs and pumps it to the body.

Part 2 of 9Structure of the heart

Structure	Side	Function
Right atrium	Right	Receives deoxygenated blood from the vena cava
Right ventricle	Right	Pumps blood to the lungs through the pulmonary artery
Left atrium	Left	Receives oxygenated blood from the lungs through the pulmonary vein
Left ventricle	Left	Pumps blood to the body through the aorta
Septum	Between the sides	Separates oxygenated and deoxygenated blood
Coronary arteries	On the surface	Supply the heart muscle with blood

Part 3 of 9Vessels at the heart

Veins

Veins blood is pumped towards the heart in veins.

Arteries

Arteries blood is pumped away from the heart in arteries.
Memory aid
- arteries carry blood Away from the heart.

Part 4 of 9Wall thickness

Ventricles

Ventricles they have thicker muscle walls than the atria because they pump blood out of the heart.

Left ventricle

Left ventricle has a thicker wall than the right ventricle because it pumps blood at high pressure around the whole body.

Right ventricle

Right ventricle pumps at lower pressure to the lungs.

Part 5 of 9Septum

Function
- the muscle wall prevents mixing of oxygenated and deoxygenated blood.

Part 6 of 9Blood supply to the heart

Cardiac muscle

Cardiac muscle it needs its own supply of oxygen and glucose.

Coronary arteries

Coronary arteries they carry this blood, and they run over the surface of the heart.

Part 7 of 9Route of blood through the heart

Vena cava
Right atrium
Right ventricle
Pulmonary artery to the lungs
Pulmonary vein from the lungs
Left atrium
Left ventricle
Aorta to the body

Part 8 of 9More from the specification

Part 9 of 9More on this topic

Atria
- upper chambers that receive blood.

Term	Meaning
Circulatory system	The organ system that transports blood.
Double circulation	A circulation in which blood passes through the heart twice per circuit.
Septum	The muscle wall separating the two sides of the heart.
Atrium	An upper chamber of the heart that receives blood.
Ventricle	A lower chamber of the heart that pumps blood out.
Coronary artery	An artery that supplies the heart muscle.
Valve	A structure that stops blood flowing backwards.

Key terms

Term	Meaning
Atrium	A heart chamber that receives blood.
Ventricle	A heart chamber that pumps blood out.
Septum	The wall of muscle between the left and right sides.
Vena cava	The vein that brings blood from the body to the right atrium.
Aorta	The artery that takes blood from the left ventricle to the body.
Pulmonary artery	The artery that takes blood from the heart to the lungs.
Pulmonary vein	The vein that brings blood from the lungs to the heart.
Coronary artery	An artery that supplies the heart muscle.

Avoid these mistakes

Saying the left side of a diagram is the left of the body — the diagram shows the heart as if in the chest.

Saying the right ventricle has the thickest wall — the left does.

Saying the heart takes its oxygen from the blood in its chambers — the coronary arteries supply it.

Saying blood in the left side is deoxygenated — the left side carries oxygenated blood.

Last updated: 15 October 2026