Lung cavity {lung}| is closed chamber, at same pressure as air pressure.
Air goes to a tube {trachea, lung} {windpipe}| to lungs.
Windpipe branches into two tubes {bronchus}| {bronchi}, at first-rib level. Bronchi have smooth muscle and cilia, which send foreign particles back toward larynx. In response to irritation or stress, asthma can cause smooth muscle to contract uncontrollably.
Bronchi branch many times and end in open regions {air sac, lung}.
Air sacs have cavities {alveoli}| {alveolus} that have moist mucus walls surrounded by capillaries, which allow gas diffusion into and out of blood. They have air that is higher in carbon dioxide, lower in oxygen, warmer, and more humid, than outside air. Elastic connective tissue surrounds alveoli to aid contraction.
lung cavity and lung lining {pleura, lung}|.
When lung muscles {diaphragm, lung}| contract and rib muscles relax, air cavity expands, pressure lowers, and lungs draw in air for inhalation.
4-Zoology-Organ-Respiration-Parts
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Date Modified: 2022.0225