Human lung

Human lung

Infobox Anatomy
Latin = pulmo
GraySubject = 240
GrayPage = 1093

Caption = Frontal view of lungs cut open
Trachea branches into bronchi

Caption2 =
Precursor =
System =
Artery =
Vein =
Nerve =
Lymph =
MeshName = Lung
MeshNumber = A04.411
DorlandsPre =
DorlandsSuf =
The human lungs are the human organs of respiration.

Humans have two lungs, with the left being divided into two lobes and the right into three lobes. Together, the lungs contain approximately 1500 miles (2,400 km) of airways and 300 to 500 million alveoli, having a total surface area of about 70 m2 in adults — roughly the same area as a badmiton court. [cite book |author=Notter, Robert H. |title=Lung surfactants: basic science and clinical applications |publisher=Marcel Dekker |location=New York, N.Y |year=2000 |pages=120 |isbn=0-8247-0401-0 |oclc= |url= |accessdate=2008-10-11] Furthermore, if all of the capillaries that surround the alveoli were unwound and laid end to end, they would extend for about 620 miles.


* The conducting zone contains the trachea, the bronchi, the bronchioles, and the terminal bronchioles
* The respiratory zone contains the respiratory bronchioles, the alveolar ducts, and the alveoli.

The conducting zone and the respiratory zone (but not the alveoli) are made up of airways.

The conducting zone has no gas exchange with the blood, and is reinforced with cartilage and smooth muscle, which are very strong. Smooth muscle has variable resistance to air flow. The conducting zone warms the air to 37 degrees Celsius and humidifies the air. It also cleanses the air by removing particles. Every time you breathe in and out your lungs are hard at work.Your lungs are surround by your rib cage.

The respiratory zone is the site of gas exchange with blood.

The smooth muscle tone in bronchioles, and therefore bronchiolar diameter, is controlled by:

* the sympathetic nervous system via noradrenaline acting on the beta receptors and causes bronchodilation
* the parasympathetic nervous system via acetylcholine which acts on the M-1 muscarinic receptors and maintains the resting tone of the bronchiolar smooth muscle. This action is related, although considered distinct from bronchoconstriction
* many other non-autonomic nervous and biochemical stimuli including, for example, carbon dioxide.

The intrapleural space is the potential space between the pleura lining the inner wall of the thoracic cage and the pleura lining the lungs.


Total lung capacity (TLC) includes inspiratory reserve volume, tidal volume, expiratory reserve volume, and residual volume.cite book | author = Weinberger SE | title = Principles of Pulmonary Medicine | edition = 4th ed.| publisher = Saunders | year = 2004 | id = ISBN 0-7216-9548-5 ] The total lung capacity depends on the person's age, height, weight, sex, and normally ranges between 4,000 and 6,000 cm3 (4 to 6 L). For example, females tend to have a 20–25% lower capacity than males. Tall people tend to have a larger total lung capacity than shorter people. Smokers have a lower capacity than nonsmokers. Lung capacity is also affected by altitude. People who are born and live at sea level will have a smaller lung capacity than people who spend their lives at a high altitude. In addition to the total lung capacity, one also measures the tidal volume, the volume breathed in with an average breath, which is about 500 cm3. For a detailed discussion of the various lung volumes, see the article on lung volumes. [cite book
last = Maton
first = Anthea
authorlink =
coauthors = Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright
title = Human Biology and Health
publisher = Prentice Hall
date = 1993
location = Englewood Cliffs, New Jersey, USA
pages =
url =
doi =
id =
isbn = 0-13-981176-1

Typical resting adult respiratory rates are 10–20 breaths per minute with 1/3 of the breath time in inspiration.

Human lungs are to a certain extent 'overbuilt' and have a tremendous reserve volume as compared to the oxygen exchange requirements when at rest. This is the reason that individuals can smoke for years without having a noticeable decrease in lung function while still or moving slowly; in situations like these only a small portion of the lungs are actually perfused with blood for gas exchange. As oxygen requirements increase due to exercise, a greater volume of the lungs is perfused, allowing the body to reach its CO2/O2 exchange requirements.


Diseases of the human lung belong to respiratory diseases. The following is a list of important medical conditions involving the lung. Many of these are caused or worsened by smoking.

* Lung cancer
* Emphysema is an enlargement of the air spaces in the lung, making it hard to breathe.
* Asthma is an immunological disease which causes the bronchioles to narrow by inflammation and spasm of the lining of the airway wall.
* Cystic fibrosis is a hereditary disease which causes the lung to produce abnormally viscous mucus.
* A pulmonary embolism occurs when a blood clot obstructs an artery leading to the lung.
* Tuberculosis is a transmittable bacterial infection of the lung, the most common infectious disease today.
* Pneumonia is an infection of the lung, caused by bacteria, viruses or fungi.
* Pneumoconiosis, an occupational lung disease caused by the inhalation of dust.
* Bronchitis is an inflammation of the bronchi.
* A collapsed lung (pneumothorax) can occur when one or both walls of the pleural cavity are penetrated by injury, allowing air to enter.
* In pulmonary edema fluid from the capillaries enters the alveoli. This can be caused by weakness of the left side of the heart (resulting in a blood holdup in the lung), altitude sickness, or rarely inhaling toxic gases.
* Lung pinprick condition is a hereditary disease which results in decreased lung capacity and occasional shortness of breath.

Transplantation now allows for a person to have a single lung transplant, a double-lung transplant, or a transplant of both the heart and lungs.

Modification of substances

The lungs convert angiotensin I to angiotensin II. In addition, they remove several blood-bourne substances, e.g. PGE1, PGE2, PGF, leukotrienes, serotonin, bradykinin. cite book |author=Walter F., PhD. Boron |title=Medical Physiology: A Cellular And Molecular Approaoch |publisher=Elsevier/Saunders |location= |year=2004 |pages= |isbn=1-4160-2328-3 |oclc= |doi= |accessdate= Page 605 ]


Additional images

Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Development of human lung — The development of human lung arises from the laryngotracheal groove. The larynx, trachea, bronchi and lungs begin to form during the fourth week of embryonic development.[1] At this time, the respiratory diverticulum (lung bud) appears ventrally …   Wikipedia

  • Lung cancer — Classification and external resources Cross section of a human lung. The white area in the upper lobe is cancer; the black areas are discoloration due to smoking. ICD 10 C …   Wikipedia

  • Lung transplantation — Intervention ICD 9 CM 33.5 MeSH …   Wikipedia

  • Lung volumes — refers to physical differences in lung volume, while lung capacities represent different combinations of lung volumes, usually in relation to inhalation and exhalation.The average pair of human lungs can hold about 6 liters of air, but only a… …   Wikipedia

  • Lung — For other uses, see Lung (disambiguation). Lunged redirects here. For other uses, see Lunge. The lungs of a pig …   Wikipedia

  • Lung (Tibetan Buddhism) — Lung (Tibetan: rlung ) is a word that means wind or breath. It is a key concept in the Vajrayana traditions of Tibetan Buddhism and as such is part of the symbolic twilight language , used to non conceptually point to a variety of meanings. Lung… …   Wikipedia

  • Human anatomical terms — make up a distinct nomenclature to describe areas of the body, to provide orientation when describing parts of human anatomy, cite web | url=| title= Introduction page, Anatomy of the Human Body . Henry Gray.… …   Wikipedia

  • lung — (n.) human respiratory organ, c.1300, from O.E. lungen (pl.), from P.Gmc. *lungw (Cf. O.N. lunge, O.Fris. lungen, M.Du. longhe, Du. long, O.H.G. lungun, Ger. lunge lung ), lit. the light organ, from PIE *legwh not heavy, having little weight;… …   Etymology dictionary

  • Human genetic engineering — is the genetic engineering of humans by modifying the genotype of the unborn individual to control what traits it will possess when born. [Citation last = Singer first = Peter author link = last2 = Kuhese first2 = Helga author2 link = title =… …   Wikipedia

  • Human adaptation to space — Human physiological adaptation to space is a challenge faced in developing human spaceflight. The turn of the 21st century saw increased research into how humans can survive and work in space for long periods.Importance of subjectThe sum of… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”