| 翻訳と辞書 |
| pulmonary alveolus ： ウィキペディア英語版 |
pulmonary alveolus
An alveolus (plural: alveoli, from Latin ''alveolus'', "little cavity") is an anatomical structure that has the form of a hollow cavity. Found in the lung parenchyma, the pulmonary alveoli are the terminal ends of the respiratory tree, which outcrop from either alveolar sacs or alveolar ducts, which are both sites of gas exchange with the blood as well. Alveoli are particular to mammalian lungs. Different structures are involved in gas exchange in other vertebrates. The alveolar membrane is the gas-exchange surface. Carbon dioxide rich blood is pumped from the rest of the body into the alveolar blood vessels where, through diffusion, it releases its carbon dioxide and absorbs oxygen.〔C. Michael Hogan. 2011. ("Respiration". ''Encyclopedia of Earth''. Eds. Mark McGinley & C. J. Cleveland. National council for Science and the Environment. Washington, D.C. )〕
==Structure==
The alveoli are located in the respiratory zone of the lungs, at the distal termination of the alveolar ducts and atria. These air sacs are the forming and termination point of the respiratory tract. They provide total surface area of about 75 m2.
A typical pair of human lungs contain about 700 million alveoli,〔("Clinical Naturopathic Medicine" ) Leah,Hechtman. pg.420. 2012〕 producing 70m2 of surface area.〔Roberts, M., Reiss, M., Monger, G. (2000) "Gaseous exchange." ''Advanced Biology''. Surrey, Nelson. p. 167.〕 Each alveolus is wrapped in a fine mesh of capillaries covering about 70% of its area. An adult alveolus has an average diameter of 200 micrometres, with an increase in diameter during inhalation.
The alveoli consist of an epithelial layer and extracellular matrix surrounded by capillaries. In some alveolar walls there are pores between alveoli called Pores of Kohn. The alveoli contain some collagen and elastic fibres. The elastic fibers allow the alveoli to stretch as they are filled with air during inhalation. They then spring back during exhalation in order to expel the carbon dioxide-rich air.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
■ウィキペディアで「pulmonary alveolus」の詳細全文を読む
スポンサード リンク
| 翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|