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See also: Respiratory tract
A complete, schematic view of the human respiratory system with their parts and functions. Latin
The respiratory system (or ventilatory system) is the biological system that introduces respiratory gases to the interior and performs gas exchange. In humans and other mammals, the anatomical features of the respiratory system include airways, lungs, and the respiratory muscles. Molecules of oxygen and carbon dioxide are passively exchanged, by diffusion, between the gaseous external environment and the blood. This exchange process occurs in the alveolar region of the lungs. Other animals, such as insects, have respiratory systems with very simple anatomical features, and in amphibians even the skin plays a vital role in gas exchange. Plants also have respiratory systems but the directionality of gas exchange can be opposite to that in animals. The respiratory system in plants also includes anatomical features such as holes on the undersides of leaves known as stomata. Contents [hide]
1 Comparative anatomy and physiology
2 Anatomy in invertebrates
3 Physiology in mammals
3.2 Gas exchange
3.3 Immune functions
3.4 Metabolic and endocrine functions of the lungs
3.4.2 Temperature control
3.4.3 Coughing and sneezing
4.1 Humans and mammals
8 External links
Comparative anatomy and physiology
Horses are obligate nasal breathers which means that they are different from many other mammals because they do not have the option of breathing through their mouths and must take in oxygen through their noses. Elephants
The elephant is the only animal known to have no pleural space. Rather, the parietal and visceral pleura are both composed of dense connective tissue and joined to each other via loose connective tissue. This lack of a pleural space, along with an unusually thick diaphragm, are thought to be evolutionary adaptations allowing the elephant to remain underwater for long periods of time while breathing through its trunk which emerges as a snorkel. Birds
The main section for this topic is on the page Bird anatomy, in the section Respiratory system. The respiratory system of birds differs significantly from that found in mammals, containing unique anatomical features such as air sacs. The lungs of birds also do not have the capacity to inflate as birds lack a diaphragm and a pleural cavity. Gas exchange in birds occurs between air capillaries and blood capillaries, rather than in alveoli. Reptiles
X-ray video of a female American alligator while breathing.
The anatomical structure of the lungs is less complex in reptiles than in mammals, with reptiles lacking the very extensive airway tree structure found in mammalian lungs. Gas exchange in reptiles still occurs in alveoli however, reptiles do not possess a diaphragm. Thus, breathing occurs via a change in the volume of the body cavity which is controlled by contraction of intercostal muscles in all reptiles except turtles. In turtles, contraction of specific pairs of flank muscles governs inspiration or expiration. Amphibians
Both the lungs and the skin serve as respiratory organs in amphibians. The skin of these animals is highly vascularized and moist, with moisture maintained via secretion of mucus from specialized cells. While the lungs are of primary importance to breathing control, the skin's unique properties aid rapid gas exchange when amphibians are submerged in oxygen-rich water. Fish
In most fish respiration takes place through gills. (See also aquatic respiration.) Lungfish, however, do possess one or two lungs. The labyrinth fish have developed a...
References: ^ Maton, Anthea; Jean, Hopkins Susan, Johnson Charles William, McLaughlin Maryanna Quon Warner David, LaHart Wright, Jill (2010). Human Biology and Health. Englewood Cliffs: Prentice Hall. pp. 108–118. ISBN 0134234359.
^ West, John B.; Ravichandran (1993). "Snorkel breathing in the elephant explains the unique anatomy of its pleura". Respiration Physiology 126 (1): 1–8. doi:10.1016/S0034-5687(01)00203-1. PMID 11311306.
^ West, John B. (2002). "Why doesn 't the elephant have a pleural space?". News Physiol Sci 17: 47–50. PMID 11909991.
^ Britannica On-line Encyclopedia
^ Gottlieb, G; Jackson DC (1976)
^ Lighton, JRB (January 1996)
Anatomy: Lower RT respiratory system (TA A06.3–5, TH H3.05.02, GA 11.1084)
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Anatomy, Respiratory system: Thoracic cavity (TA A07, TH H3.05.03, GA 11.1087)
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