How does breathing occur in humans?

The breathing
All cells in the body need oxygen to function. They get this oxygen through the respiratory system.
When inhaled, oxygen enters the lungs and is released into the blood. The blood distributes the oxygen throughout the body and carries back carbon dioxide. Carbon dioxide is a metabolic waste product. When you exhale, the carbon dioxide is then removed from the body.

The respiratory organs
The respiratory system consists of the airways, the pulmonary vessels, the lungs themselves and the respiratory muscles.
To get to the lungs, the air first passes through the mouth, nasal cavities, throat, larynx, and windpipe, and then goes to the main bronchi.
The bronchi then lead directly to the two lungs.
The lungs are one of the largest organs in the body. The outer tissue of the lungs is 30 to 50 times the size of the entire body surface, i.e. around 70 square meters!
The lungs and circulatory system work together to do their most important job, gas exchange and the distribution of oxygen throughout the body.


The air we breathe consists of:
78% nitrogen
21% oxygen
0.03% carbon dioxide
0.07% noble gases
Pure oxygen is dangerous; it can even damage the lungs.

Why are we yawning?
It used to be believed for a long time that yawning was due to a lack of oxygen in the brain. This theory has long since been refuted by laboratory tests.
Most of the time we yawn when we are tired or bored. It is established that yawning is a reflex and mostly quite contagious, but unfortunately the exact cause is unknown.

Useful cough?
Pollutants also get into the lungs with the air.
If the lungs can no longer cope with this inhaled dirt, an urge to cough is triggered and also hurls small mucus particles and foreign bodies out at speeds of up to 160 kilometers per hour

Sneezing with an effect
Sneezing protects the lungs from dust and small debris


Did you know already, ...

.... that an adult needs 9,000 liters of air to breathe every day?

.... that the two lungs contain approx. 300 to 450 million alveoli?

.... that the two lungs are different sizes? The left lung is smaller and weighs about 100 grams less. it also only has two lobes of the lungs, but a bulge for the heart.

..... that the lungs are actually pale pink, but gradually turn gray to black due to dirt particles?

.... that there is always about 1.5 liters of air left in the lungs? This is necessary so that there is always an emergency reserve in case you cannot breathe for a short time.

Journey to the lungs
What is the diaphragm?
Check your lung capacity!
Yawn Research for Children

Respiratory system diseases
Chronic bronchitis
to cough
lung infection
Lung cancer

Body side
You can find more about the body at
My body and me

Inner and outer breathing

External breathing ensures gas exchange
(Oxygen uptake - carbon dioxide release) in the lungs and takes place in the walls of the small alveoli, the alveoli.

Pulmonary alveoli, drawn by Simone Müller

The cells throughout the body need oxygen in order to burn the nutrients contained in the food and to function properly, which in turn creates carbon dioxide that has to be transported out. The exchange between blood and cells is also called internal breathing.

The body cannot store oxygen, so humans have to breathe day and night. It all happens automatically. Your brain determines how much you breathe.

The number of breaths per minute
Adultapprox. 12-15
Adolescentapprox. 15-20
School childapprox. 20
small childapprox. 25
infantapprox. 30
Premature / newbornapprox. 40-60

Every normal breath takes in about half a liter of air, and with exertion this can be ten times as much!
When you exercise, you also exercise your lungs because the muscles need more oxygen. So that the oxygen gets to your arms and legs faster, your heart starts beating faster too!