Editing Human body (section)

==== Respiratory system ====
{{Main|Respiratory system}}

The [[respiratory system]] consists of the nose, [[Pharynx|nasopharynx]], [[trachea]], and [[Lung|lungs]]. It brings oxygen from the air and excretes [[carbon dioxide]] and water back into the air. First, [[Atmosphere of Earth|air]] is pulled through the trachea into the lungs by the [[thoracic diaphragm|diaphragm]] pushing down, which creates a [[vacuum]]. Air is briefly stored inside small sacs known as [[Pulmonary alveolus|alveoli]] (sing.: alveolus) before being expelled from the lungs when the diaphragm contracts again. Each alveolus is surrounded by [[Capillary|capillaries]] carrying deoxygenated blood, which absorbs oxygen out of the air and into the [[Circulatory system|bloodstream]].<ref>{{cite book |last1=Maton |first1=Anthea|first2=Jean |last2= Hopkins |first3=Susan |last3=Johnson|first4=Charles William |last4= McLaughlin |first5=Maryanna Quon |last5=Warner |first6=David |last6= LaHart |first7=Jill D. |last7=Wright |title=Human Biology and Health |publisher=[[Prentice Hall]] |year=2010 |pages=108–118 |isbn=978-0-13-423435-9}}</ref><ref name="webmd.com">{{Cite web|title=Respiratory System|url=https://www.webmd.com/lung/how-we-breathe|access-date=2023-02-08|website=WebMD|language=en}}</ref>

For the respiratory system to function properly, there need to be as few impediments as possible to the movement of air within the lungs. [[Inflammation]] of the lungs and excess [[mucus]] are common sources of breathing difficulties.<ref name="webmd.com"/> In [[asthma]], the respiratory system is persistently inflamed, causing [[Wheeze|wheezing]] or [[shortness of breath]]. [[Pneumonia]] occurs through [[infection]] of the alveoli, and may be caused by [[tuberculosis]]. [[Chronic obstructive pulmonary disease|Emphysema]], commonly a result of [[smoking]], is caused by damage to connections between the alveoli.<ref>{{Cite web|last=Hoffman|first=Matthew|title=Lung Diseases Overview|url=https://www.webmd.com/lung/lung-diseases-overview|access-date=2023-02-08|website=WebMD|language=en}}</ref>