Your heart is a vitally important pump which beats every second of everyday pumping blood around your body. 

Its design is complex with many different parts and connections – here is an overview of your hearts structure and function.

Heart structure

A normal heart has two separate sides with different roles working closely together. The right side receives blood from the body and pumps it to the lungs (to be topped up with the oxygen we breath in), and the left side receives blood from the lungs before pumping it around the body. Each side is made up of two rooms or chambers, each of which has a specific role.

The top chambers are called the Right Atrium and Left Atrium; these collect the blood returning from the body and lungs respectively.

The bottom chambers are called the Right Ventricle and Left Ventricle; these are the two pumping chambers, pumping blood to the lungs (blood to be topped up with oxygen) and around the body respectively.

Separating the heart chambers are valves made of tough flexible tissue which open and close in response to pressure changes within the heart chambers. These are the doors controlling the smooth flow of blood through your heart ensuring it is working as efficiently as possible, i.e. moving forwards, not backwards.

Heart Muscle

The Left Ventricle is usually the largest and most muscular heart chamber as its primary function is to pump blood (freshly topped up with oxygen by the lungs) out of the heart and around your body delivering oxygen and nutrients to your brain, organs, muscles and tissue. 

During each heartbeat, the Left Ventricle contracts and squeezes, forcing blood out of the heart along blood vessels called arteries. In doing so it generates and maintains pressure within the arteries to keep your blood flowing.

The volume of blood being forced out of your Left Ventricle generates an increased pressure within the arteries which reaches a peak pressure called Systolic Blood Pressure.

After the Left Ventricle finishes contracting, it begins to relax. As the muscular walls relax, the Left Ventricle refills with blood from the Left Atrium, prior to the next contraction.

This relaxation between heatbeats causes the blood pressure in the arteries to drop to its resting level called Diastolic Blood Pressure.


The pressure wave of blood travelling along the inside of the arteries is the pulse you can feel when you check to see how fast your heart is beating.


Very little would happen in your body without a small bit of electricity! This is especially true of muscles, which need a small electrical impulse to stimulate them to contract. Since your heart is a muscular pump, every heartbeat is immediately preceded by a small electrical impulse which travels through the heart along a network of nerves called the Cardiac Conduction System.

Each electrical impulse starts high up in the Right Atrium in a region know as the Sinoatrial Node (SA Node). It then travels across the top two heart chambers (the Atria) causing them to contract simultaneously, before reaching the mid-point between the top and bottom chambers, a region known as the Atrioventricular Node (AV Node). Here, there is a short delay as the electrical impulse travels slower through the AV Node.

Once through, the electrical impulse travels fast along nerve fibres within the muscular walls of the ventricles causing them to contract simultaneously.

After a short recharge time, another electrical impulse fires from the SA Node and follows the same pathway.