# data[].attributes.body
There is more carbon dioxide and water vapor which is evaporated from the moist walls of the alveoli, less oxygen in expired air than in inspired air.

# data[].attributes.body
The internal intercostal muscles contract and the external intercostal muscles relax to lowers the ribs downwards and inwards. The muscle in the diaphragm relaxes and it bugles up due to pressure from the organs below and contraction of the abdominal muscles. These two actions decrease the volume inside the thorax, causing the pressure inside the thorax to increase.

*see figure Expiration (breathing out)

# data[].attributes.body
People need to breathe air into their lungs in order to get oxygen. People breathe air out of their lungs to get rid of carbon dioxide. People need oxygen in aerobic respiration in the breakdown of glucose and obtain energy. Therefore, gas exchange system and breathing is crucial for our life, it's better for us to learn the 'story of breathing' and get known with our body.

# data[].attributes.headline
goblet cell and ciliated epithelial cells keep the lungs free of dust and pathogen

# data[].attributes.subject
goblet cell and ciliated epithelial cells keep the lungs free of dust and pathogen

# data[].attributes.body
Exhalation means breathing out.

There is a considerable number of carbon dioxide in the capillary needs to be carry out from our blood through gas exchange, because carbon dioxide is a waste gas made in respiration. It can become toxic if it builds up in cells. It has been carried there from the respiring tissues in the blood plasma. It diffuses in the opposite direction of inspiration, through the capillary wall across the alveolar wall into the space inside the alveolus and breathe out. The elastic recoil of the alveoli helps to force air out of the lungs.

# data[].attributes.body
Inhalation means breathing in.

Air enters the mouth or nose, the hairs inside the nose filter the air and removing particles and some pathogens.

Air passes through the throat to the larynx (voice-box).

Air enters the trachea (windpipe), cartilage keeps it open when air passes through it. Trachea divides into two branches called bronchi and connect each lung. Trachea, bronchi and bronchioles are lined with ciliated epithelial cells and goblet cells which secrete mucus. Dust particles and pathogens become trapped in the slimy mucus. The cilia beat to carry a stream of mucus up to our nose and throat, removing the particles and pathogen we then swallow.

*see figure goblet cell and ciliated epithelial cells keep the lungs free of dust and pathogen

As the air enters lungs, the external muscles contract and the internal intercostals muscles between ribs relax, raising the ribs upward and outwards. A sheet of fibrous tissue and muscle that separates the thorax from abdomen called diaphragm contracts and flattens at the same time to pull on the lungs so they occupy a larger volume and increase the volume inside the thorax. These decreases the air pressure inside the lungs to below the pressure of atmospheric air so that air moves in through our nose and mouth and the air inflate.

*see figure Inspiration (breathing in)

Air goes from bronchi to many small bronchioles, the end of it is the tiny air sacs called alveoli.

Air enters alveoli and gas exchange takes place. Alveoli are well adapted for gas change as there is a very large number of alveoli in the lungs to give a huge surface area for diffusion, and the alveoli have thin walls made of a single layer of cells so there is a short distance for diffusion. Each of them is moist so oxygen dissolves in this watery fluid before diffusing through the walls in to blood. Each alveolus is surrounded by a network of blood capillaries, oxygen molecules from the alveolus diffuse into the red blood cells and combine with hemoglobin, the blood cells can then transport this oxygen to the body tissues.

*see figure Gas exchange at an alveolus

# data[].attributes.body
Ventilation requires pressure changes to occur in the lungs, so that air can be forced in an out of the alveloi.The pressure changes are brought about by the movement of two sets.