What is the respiratory system?
It is your body’s gas-exchange system. Your cells need a steady supply of oxygen and make carbon dioxide as a waste gas, and the lungs are where one is swapped for the other. NHLBI, the US lung and heart institute, calls this swap gas exchange. Everything else in the system exists to get air to that point, clean it on the way and push the old air back out.
You’ve probably searched this for a biology class, or because something felt off with your breathing. Either is fine. If it’s the second, and it’s sudden or severe, stop reading and get medical help.
What are the parts of the respiratory system?
Follow the air from the outside in. Here’s each organ and its one main job:
| Part | Main job |
|---|---|
| Nose and nasal cavity | Take in air, warm and moisten it, trap dust |
| Mouth | A second way in, without the nose’s filtering |
| Pharynx (throat) | Carries air along the airway |
| Larynx (voice box) | Carries air and produces sound for speech |
| Trachea (windpipe) | The main tube down into the chest |
| Bronchi and bronchioles | Branching tubes that spread air through each lung |
| Alveoli | Tiny air sacs where oxygen and carbon dioxide swap |
| Lungs | Hold it all: three lobes on the right, two on the left |
| Diaphragm | The muscle that pulls air in and lets it out |
| Cilia and mucus | Catch dust and germs so you can cough or sneeze them out |
How does the respiratory system work?
One breath, in five steps:
- The diaphragm pulls downIt sits under your lungs like a dome. As it drops, your chest gets bigger and air flows in.
- Air gets conditionedYour nose or mouth warms and moistens it on the way past.
- Air travels down the treeLarynx, windpipe, bronchi, bronchioles, each branch narrower than the last.
- The swap happensIn the alveoli, oxygen moves into the tiny blood vessels around each sac and carbon dioxide moves out of them.
- The diaphragm risesYour chest gets smaller, and the old air leaves the way it came.
Then your blood takes over. How the circulatory and respiratory systems work together covers the second half of the trip.
Feel it: one minute of slow breaths
In for 5, out for 5. Notice your belly and lower ribs moving as your diaphragm works.
5 in · 5 out
Follow the orb: in as it grows, out as it shrinks.
Seconds per phase: 5 in · 5 out. Turn on JavaScript to use the timer.
Runs in your browser: nothing is saved or sent. For haptic taps with your eyes closed, or on your wrist, use ATHA on iPhone or Apple Watch.
What are the functions of the respiratory system?
Gas exchange is the headline, but Cleveland Clinic lists a few side jobs too:
- Warming, moistening and filtering the air you breathe
- Making speech possible, by pushing air through the voice box
- Helping you smell
- Helping keep your body’s acid-base balance steady
- Clearing irritants, through mucus, coughing and sneezing
Which part of breathing can you control?
Almost all of the time, none of it needs you. Breathing centres in your brain adjust your rate using signals from sensors that track carbon dioxide and oxygen levels. But NHLBI points out you can also change your breathing on purpose, up to a point. Holding your breath and singing are the everyday examples.
That small override is what makes breathing exercises possible. You can’t will your heart to slow down, but you can stretch an out-breath. And a 2018 review linked slow breathing, under 10 breaths a minute, with higher heart-rate variability, while noting that the studies were small and mixed. Interesting, promising, not magic.
Respiratory system search terms, explained
| Term | What it means |
|---|---|
| Respiratory | To do with breathing and the lungs |
| Respiration | The exchange of oxygen and carbon dioxide |
| Respiratory rate | Breaths per minute; 12 to 18 is normal for a resting adult |
| Respiratory care | Treatment from specialists, or looking after your lungs day to day |
| Respiratory diseases | Conditions affecting the airways, lungs or their blood supply |
| Diaphragmatic breathing | Slow breathing that leads with the belly, not the upper chest |
Explaining this to a child? There’s a kid-friendly version with fun facts.
Common questions
What are the main organs of the respiratory system?
The nose and mouth, pharynx (throat), larynx (voice box), trachea (windpipe), bronchi and bronchioles, and the lungs with their alveoli. The diaphragm is the main muscle that drives breathing.
What is the main function of the respiratory system?
Gas exchange: getting oxygen into your blood and carbon dioxide out of it. It also conditions the air you breathe, makes speech possible and helps you smell.
Where does gas exchange happen?
In the alveoli, tiny air sacs at the end of the smallest airways. Oxygen passes into the tiny blood vessels around them, and carbon dioxide passes out to be breathed away.
Why is the right lung different from the left?
The right lung has three lobes and the left has two. The left lung also has a dip that makes room for the heart.
Is breathing voluntary or involuntary?
Both. It runs automatically under the control of your brain, but you can change it on purpose for a while, such as when you hold your breath, sing or do a breathing exercise.
Where does ATHA fit in?
I built ATHA around that one override: the part of the respiratory system you can steer. Open it, pick a rhythm like Coherence (5 in, 5 out), and a visual, haptic taps or spoken cues keep the count, so you don’t have to.
Questions, corrections or a topic you want explained next? Send them my way.
Indie iOS developer, and the maker of ATHA. Say hello on Instagram or at solostaseraofficial@gmail.com.
Sources
Checked on 3 November 2026.
- NHLBI: The respiratory system · Last updated 24 March 2022.
- NHLBI: How the lungs work · Last updated 24 March 2022.
- NHLBI: How your body controls breathing · Last updated 24 March 2022.
- Cleveland Clinic: Respiratory system · Last updated 9 April 2024.
- KidsHealth (Nemours): Your lungs and respiratory system · Medically reviewed January 2023.
- Cleveland Clinic: Vital signs · Last updated 15 March 2023.
- Zaccaro A et al. How breath-control can change your life: a systematic review on psycho-physiological correlates of slow breathing. Frontiers in Human Neuroscience, 2018
ATHA is a breathing and mindfulness app, not a medical device, and this guide is general information, not medical advice. It doesn’t diagnose or treat any condition. For a symptom that is persistent, severe or worrying, talk to a doctor. In an emergency, call your local emergency number.