The Structure and Function of the Heart – Simplified

To successfully navigate the L2 Gym Instructing qualification, you will need an understanding of ‘The Structure and Function of the heart’.

We have developed a simple cheat sheet, that will help you.

What you will learn

  • What is included in the cardiovascular system
  • The basic structure of the heart
  • The basic function of the heart
  • What are valves

What is the circulatory system?

Put simply, the circulatory system is the process by which the hearts pumps blood throughout the body, as well as transports nutrients, hormones, oxygen and other gases to and from cells.

Its made up of the heart, blood vessels and blood.


The heart

The heart is a muscular pump that is located in the left side of the chest cavity, between the 2 lungs and behind the sternum.

It is around the size of a human fist, between 200 – 425 grams

Beats about 70 times per minutes (approx. 100,000 times per day).


The Structure of the heart

The heart is made up of myocardium (thick muscular walls), and wrapped around a layered sac (Pericardium)

A film of fluid exists between 2 layers of the sac, which prevents friction as the heart beats

It is divided into 2 halves, 4 chambers.

The right side is smaller and takes blood to the lungs, whilst the left side is larger and takes blood to the body.

Each side has an Atium and a Ventricle.

Artia receives blood and pumps it to the ventricles, they have thin walls and are smaller.

The Ventricles generate the force to push blood through the body, their walls are thick and they are larger than the atria.


Heart valves

There are several different valves around the heart, which all perform slightly different tasks.

To keep things simple, valves prevent the backflow of blood.

We want our blood flowing in one continuous direction, valves help this process.


The flow of blood through the heart

After our body has made use of the oxygen, carbon dioxide needs to be removed from the body.

This travels back to the heart in the blood, we call this deoxygenated blood.

Here is the simple process that blood follows:

  1. The deoxygenated blood enters the heart through the right atrium (a collecting chamber), from the Vena Cava (vein).
  2. There is a contraction that forces the deoxygenated blood through the heart valve and into the right ventricle.
  3. The contraction forces the deoxygenated blood through another valve, into the pulmanory artery
  4. The deoxygenated blood then enters the lungs, where the carbon dioxide leaves the body and oxygen enters the body
  5. The oxygenated blood leaves the heart through the pulmanory vein, and then enters the left atrium
  6. As per the right side, the contraction forces the oxygenated blood through the valve and into the left ventricle
  7. The oxygenated blood then passes through another valve, into the aorta and the rest of the body


What is the difference between veins and ateries?

Arteries carry oxygenated blood* away from the heart supplying vital organs and tissues.

A good tip is to remember the A from away… ‘A’ = ‘A’way

Arteries also deal with blood under high pressure, which is why they have thicker, muscular walls to allow blood to be circulated around the body.

* Except for the pulmonary artery – transports deoxygenated blood from the heart to the lungs


Veins carry deoxygenated blood back towards the heart*.

A tip here… Remember ‘Ve-in’ = ‘way in’

Veins have thin muscular walls, due to lower blood pressure.

Veins have valves to assist blood flow efficiently to the heart and prevent backflow, arteries don’t have valves

* Except for the pulmonary vein – transports oxygenated blood from the lungs to the heart


To wrap things up

To successfully complete the Level 2 Gym Instructing qualification, you will need a basic understanding of the structure and function of the heart.

Practice presenting the following slide.

If you can do this without looking at any course materials, you have all the knowledge you need to successfully complete this part of the course





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