The whole process of inhaling and exhaling of air is called respiration.

Respiration is a vital process that occurs in living organisms, including humans. It involves the exchange of gases, mainly oxygen and carbon dioxide, between the body and the environment. Respiration can be divided into two main types: external respiration and internal respiration.

1. External Respiration:
External respiration refers to the exchange of gases that takes place between the body and the environment. This process occurs in the respiratory system, which includes the nose, throat, trachea, bronchi, and lungs. The main steps involved in external respiration are:

- Inhalation: When we breathe in, the diaphragm and intercostal muscles contract, causing the chest cavity to expand. This expansion lowers the pressure in the lungs, allowing air to rush in through the nose or mouth.

- Gas Exchange: Once the air enters the lungs, it travels through the bronchi and bronchioles, eventually reaching the alveoli. The alveoli are small, air-filled sacs where the exchange of gases occurs. Oxygen from the inhaled air crosses the thin walls of the alveoli and enters the bloodstream, while carbon dioxide, a waste product, moves from the bloodstream into the alveoli to be exhaled.

- Exhalation: After the oxygen is absorbed by the bloodstream, the diaphragm and intercostal muscles relax, causing the chest cavity to contract. This increases the pressure in the lungs, forcing the air, now rich in carbon dioxide, to be expelled through the nose or mouth.

2. Internal Respiration:
Internal respiration refers to the exchange of gases that occurs within the cells of the body. Once oxygen is transported by the bloodstream to the body's tissues, it is used in cellular respiration, a process that produces energy. During cellular respiration, oxygen is combined with glucose (sugar) in the cells to produce carbon dioxide, water, and energy.

In summary, respiration is the entire process of inhaling and exhaling air. It involves external respiration, where the exchange of gases occurs in the respiratory system, and internal respiration, where oxygen is used by the body's cells for energy production.