Structure of the heart

Transport in animals · The heart · note 1 of 4

Spec B9.2.1, B9.2.2Download all The heart notes (PDF)Download all notes (PDF)7 pages

Structure of the heartSpec B9.2.1, B9.2.2

In short

The heart is a muscular pump with two atria, two ventricles, a septum, valves and coronary arteries that supply the heart muscle with oxygenated blood.

The mammalian heart is a pump made of cardiac muscle. You need to identify these structures in diagrams and images.

Structures of the heart
Structure	What it is or does
Muscular wall	Contracts to squeeze blood out of the chambers
Right atrium and left atrium	Upper chambers that receive blood from veins
Right ventricle and left ventricle	Lower chambers that pump blood out into arteries
Septum	Wall of muscle between the left and right sides of the heart
One-way valves	Stop blood flowing backwards
Coronary arteries	Run over the surface of the heart and supply the heart muscle with oxygenated blood (oxygen and glucose)

A vertical section of the mammalian heart drawn as if facing the person, labelled vena cava, pulmonary artery, aorta, pulmonary vein, right atrium, left atrium, right ventricle, left ventricle, semilunar valves, atrioventricular valves, septum, muscular wall and coronary arteries, with blue arrows for deoxygenated blood and red arrows for oxygenated blood. — The heart is drawn as if you are facing the person, so the **left side** of the heart is on the right of the page.

Blood is pumped away from the heart in arteries and returns to the heart in veins.

Common mistake:

The heart is drawn as if you are facing the person. The left side of the heart is on the right of the page. The coronary arteries supply the heart itself, not the lungs.

Written and checked against the Cambridge IGCSE Combined Science (0653) specification · Updated October 2026