Breathing and Respiration Are Not the Same Thing

Breathing is the physical act of taking air in and pushing it out. Respiration is the chemical process inside your cells that releases energy from food. Breathing merely delivers the oxygen; respiration is what the oxygen is for.

This page covers everything in the CBSE Class 7 Science chapter on respiration: the difference between the two processes, the parts of the respiratory system, how the ribs and diaphragm move, and how other animals breathe.

Respiration happens in every cell of the body, and can be written as:

glucose + oxygen → carbon dioxide + water + energy

The glucose comes from digested food and the oxygen from breathing. The energy released is what powers everything — moving, growing, thinking and keeping warm.

So the two processes connect directly: breathing supplies the oxygen that respiration consumes, and removes the carbon dioxide that respiration produces. Stop breathing and respiration soon stops too, because its raw material runs out.

For example, feeling warm after running is respiration releasing energy faster in your muscle cells.

The misconception to fix is that respiration happens only in the lungs. It happens in every cell; the lungs are simply where the gases are swapped with the outside air.

Air follows a fixed path in and out.

It enters through the nostrils into the nasal cavity, where it is warmed, moistened and filtered by tiny hairs and mucus. It passes down the windpipe (trachea), which divides into two bronchi, one entering each lung. Inside the lungs the bronchi branch into finer and finer tubes ending in millions of tiny air sacs called alveoli.

The ribs form a protective cage around the lungs, and the diaphragm is a sheet of muscle below them.

Gas exchange happens in the alveoli. Each alveolus has extremely thin walls and is surrounded by fine blood vessels, so oxygen passes from the air into the blood, and carbon dioxide passes from the blood into the air to be breathed out.

This is why breathing through the nose is better than through the mouth — the nasal cavity filters and warms the air first, and the mouth does neither.

Breathing works by changing the size of the chest cavity.

During inhalation, the ribs move upwards and outwards and the diaphragm moves down, flattening. The chest cavity becomes larger, and air rushes in to fill the extra space.

During exhalation, the ribs move downwards and inwards and the diaphragm moves up, curving. The chest cavity becomes smaller, and air is pushed out.

You can feel this by placing your hands on your ribs and taking a deep breath.

Breathing rate is the number of breaths taken in one minute. At rest an adult takes roughly 12 to 16 breaths per minute. After running or climbing stairs it rises sharply — because the muscles are working harder and need more energy, so respiration speeds up, demanding more oxygen and producing more carbon dioxide. Faster breathing supplies one and removes the other.

To measure it fairly, count breaths for a full minute sitting still, then repeat immediately after exercise and compare.

Every animal needs oxygen, but the organ that collects it depends on where the animal lives.

Mammals, birds and reptiles have lungs, like humans. A cow, a sparrow and a lizard all breathe this way.

Fish have gills. Water enters through the mouth and passes over the gills, which take dissolved oxygen out of it. This is why a fish taken out of water dies — its gills collapse and stick together in air, so they cannot work even though air holds far more oxygen than water.

Earthworms breathe through their moist skin, with gases passing straight through it. That is exactly why earthworms must stay damp, and why they come to the surface when heavy rain floods their burrows.

Frogs do both at different stages: a tadpole has gills and lives in water, while an adult frog breathes through lungs on land and through its moist skin, including while under water.

So the pattern is: the breathing organ suits the habitat, not the size of the animal.