what is the process when you breath in and out?
this might be kind of a long answer
sorry :(
Answers
Internal and external respiration
Our lungs supply oxygen from the outside air to the cells via the blood and cardiovascular system to enable us to obtain energy. As we breathe in, oxygen enters the lungs and diffuses into the blood. It is taken to the heart and pumped into the cells. At the same time, the carbon dioxide waste from the breakdown of sugars in the cells of the body diffuses into the blood and then diffuses from the blood into the lungs and is expelled as we breathe out. One gas (oxygen) is exchanged for another (carbon dioxide). This exchange of gases takes places both in the lungs (external respiration) and in the cells (internal respiration). Fig 1 summarises gas exchange in humans.
Bringing air into the lungs
Our respiratory system comprises a conduction zone and a respiratory zone. The conduction zone brings air from the external environment to the lungs via a series of tubes through which the air travels.
Controlling the volume of air in the lungs
We have two lungs (right and left) contained in the thoracic cavity (chest). Surrounding the lungs are ribs, which not only protect them from damage but also serve as anchors for the intercostal muscles. Beneath the lungs is a very large dome-shaped muscle, the diaphragm. All these muscles are attached to the lungs by the parietal and visceral membranes (also called parietal and visceral pleura).
The parietal membrane is attached to the muscles and the visceral membrane is attached to the lungs. The liquid between these two membranes, pleural fluid, sticks them together just as panes of glass become stuck together when wet.
As the visceral membrane covers, and is part of, the lungs and is stuck by pleural fluid to the parietal membrane, when the muscles in the thorax move, the lungs move with them. If air gets between the membranes, they become unstuck and, although the muscles can still contract and relax, they are no longer attached to the lung – as a result, the lung collapses. This abnormal collection of air in the pleural space is called a pneumothorax. If the pleural fluid liquid becomes infected, the person develops pleurisy.
When the intercostal muscles contract, they move up and away from the thoracic cavity. When the diaphragm contracts, it moves down towards the abdomen. This movement of the muscles causes the lungs to expand and fill with air, like a bellows (inhalation). Conversely, when the muscles relax, the thoracic cavity gets smaller, the volume of the lungs decreases, and air is expelled (exhalation).
Equalising pressure
When the thoracic muscles contract, the volume of the lungs expands so there is suddenly less pressure inside them. The air already in the lungs has more space, so it is not pushing against the lung walls with the same pressure. To equalise the pressure, air rushes in until the pressure is the same inside and outside. Conversely, when the muscles relax, the volume of the lungs decreases, the air in the lungs has less space and is now at high pressure, so the air is expelled until pressure is equalised. In short: