Understanding your body: a simple guide to how it works

Why does understanding your body matter?

Knowing the basics of how your body works helps you notice when something changes, and take action early. It also helps you describe symptoms clearly to a doctor, so you get the right advice sooner. You do not need medical training. A simple understanding of your body's main systems is enough to make better choices about exercise, diet and when to seek help.

What do your muscles, bones and joints do?

Your bones, muscles, joints, tendons and ligaments make up your musculoskeletal system. It supports your body, lets you move and protects your organs. Problems with this system are very common. Arthritis UK reports that musculoskeletal conditions account for 1 in 7 GP consultations.

Staying active, doing exercises that strengthen your muscles at least twice a week, keeping to a healthy weight and taking regular breaks from sitting all help keep muscles strong and joints moving well. It also helps to know the difference between common injuries. The NHS explains that a sprain is a torn or twisted ligament, while a strain is an overstretched or torn muscle.

How do your heart and circulation work?

Your heart and blood vessels make up your cardiovascular system. Your heart pumps blood around your body, delivering oxygen and nutrients and carrying away waste.

The NHS lists common symptoms of coronary heart disease as chest pain, shortness of breath, pain in your neck, shoulders, jaw or arms, and feeling faint or sick. It also notes that some people have no symptoms at all before they are diagnosed. The NHS advises calling 999 if you have chest pain that feels tight or like squeezing, chest pain that spreads to your arms, neck or jaw, or severe difficulty breathing.

Eating a balanced diet, being active, not smoking and keeping alcohol within recommended limits all help your heart. Getting your blood pressure and cholesterol checked matters too, because problems often have no symptoms. Adults in England aged 40 to 74 without certain existing conditions are invited for a free NHS Health Check every 5 years.

How do your lungs work?

Your respiratory system includes your airways and lungs. It brings oxygen into your body and removes carbon dioxide. The NHS advises seeing a GP if you have had a cough for more than 3 weeks. Cancer Research UK also lists getting out of breath doing things you used to do without a problem as a sign worth getting checked.

Not smoking and avoiding other people's smoke, staying active and keeping up to date with vaccinations all help protect your lungs.

How does digestion work?

Your digestive system includes your stomach, intestines, liver and other organs that break down food and absorb nutrients. Fibre is one of the most important parts of a healthy diet for your gut. UK government guidelines recommend adults aim for 30g of fibre a day, from foods such as fruit, vegetables, wholegrains, beans and oats, and drinking plenty of fluids helps too.

The NHS advises seeing a GP about changes in your poo that are not usual for you, blood in your poo, or losing weight without trying.

What does your nervous system do?

Your brain, spinal cord and nerves make up your nervous system. It sends messages around your body and controls everything from movement and breathing to memory and mood. Being active, eating well, limiting alcohol, getting enough sleep and protecting your head, for example by wearing a helmet when you cycle, all help.

Knowing the signs of a stroke can save a life. The NHS uses FAST to help people remember them: the face may have dropped on one side, the person may not be able to lift both arms, and their speech may be slurred. Time to call 999 if you see any of these signs.

What is the most important thing to remember?

Many of the same habits support every system in your body. Being active, eating well, sleeping well, not smoking and limiting alcohol all help. Most importantly, get to know what is normal for you, and speak to a GP if something changes and does not go away. Our guide to knowing your normal explains which changes to look out for.