Respiratory system

The respiratory system brings oxygen into your body and helps to remove carbon dioxide.

The lungs are a main part of your respiratory system. They sit in your chest and are protected by your ribcage.

Problems with your respiratory system can reduce the amount of oxygen that reaches your lungs. This can make you unwell.

The respiratory system has several important functions. These functions help the body get the oxygen it needs. Important functions are:

• Breathing — it helps you breathe air in and out.
• Gas exchange — in your lungs, oxygen goes into your blood and carbon dioxide leaves your blood.
• Filtering air — your nose filters, warms and moistens the air you breathe before it reaches your lungs.
• Protection — the respiratory system has mucus and tiny hairs that trap and remove dust and germs to keep your lungs clean.
• Sound production — the larynx (voice box) produces sound for speaking.

Your respiratory system starts at the nose and mouth. It then continues through the airways and lungs. The main parts of your respiratory system are your:

• nose and mouth
• pharynx — also known as your throat
• larynx — also known as your voice box
• epiglottis — a small flap of tissue that closes when you swallow to prevent food from entering your trachea (windpipe)
• trachea — the tube-like airway that lets air move between your larynx and your lungs.
• lungs — the body organ where gases enter and leave your blood

Each lung is divided into sections known as lobes. You have 3 lobes in your right lung and 2 lobes in your left lung. The left lung is smaller because it shares space in the chest with the heart.

Inside your lungs there are:

• bronchi — your windpipe splits into 2 smaller tubes known as bronchi
• bronchioles — your bronchi branch out into even smaller tubes known as bronchioles
• alveoli — the tiny air sacks at the end of each bronchiole, you have thousands of them
• pleura — a slippery sack that covers your lungs inside your chest

The lungs don't have their own muscles for breathing. Other muscles nearby help with breathing. The most import one is the diaphragm.

You breathe in when your diaphragm contracts and flattens out. At the same time, your chest expands, which then pulls air into your body.

When you breathe air in through your nose and mouth, it gets warmed and moistened. The air passes through your larynx.

Air then passes down the windpipe and bronchi into your lungs. On the way, mucus and tiny hairs trap dirt and germs.

Once inside your lungs, air fills small air sacs called alveoli. These sacs are next to blood vessels. Oxygen travels from your alveoli into your bloodstream from the air you breathe in. Carbon dioxide travels from your bloodstream into your alveoli. You then breathe out the carbon dioxide.

Respiratory conditions affect your airways and lungs. Respiratory conditions can be acute (short term) or chronic (long lasting).

Some examples of lung conditions that can affect the respiratory system include:

• asthma
• chronic obstructive pulmonary disease (COPD)
• hay fever

Many infections can cause respiratory problems. Infections can be caused by bacteria, viruses or fungi. Common infections are:

• colds and the flu
• COVID-19
• sinusitis, laryngitis and pharyngitis
• pneumonia
• bronchitis
• whooping cough

Respiratory infections that are common in children are:

• croup
• bronchiolitis (usually caused by respiratory syncytial virus (RSV))
• coughs and colds

Symptoms of respiratory conditions

Symptoms of problems with the airways and lungs may include:

• a runny or blocked nose
• sore throat
• breathlessness
• wheezing
• coughing with or without coughing up mucus or blood
• high temperature
• chest pain

To keep your respiratory system healthy:

• don't smoke
• avoid harmful factors such as smoke, dust and chemicals
• eat a healthy diet
• maintain a healthy weight
• have an active lifestyle

If you have a health condition, check with your doctor before you start exercising. Try to exercise away from busy roads with high levels of air pollution.

To reduce your risk of getting or spreading respiratory infections:

• wash your hands regularly
• stay home when you are unwell
• cover your mouth and nose when coughing or sneezing

Consider having the flu vaccine each year and keep up to date with your COVID-19 vaccinations. Ask your doctor about other vaccinations that help prevent respiratory conditions such as whooping cough and pneumonia.

Lung Foundation Australi (Opens in new tab)a has information and support for Australians with lung disease or lung cancer.

Visit Pregnancy Birth and Baby to learn more on colds and flu in babies and children (Opens in new tab).

You can also call the healthdirect helpline on 1800 022 222 at any time to speak to a registered nurse (known as NURSE-ON-CALL in Victoria) for more information and advice.

Other languages

Health Translations Victoria has asthma fact sheets (Opens in new tab) and first aid plans in many community languages.