What jobs that the lungs have?

Gas Exchange

The primary function of the lungs is to exchange oxygen and carbon dioxide between the air and the bloodstream. This exchange occurs in the alveoli, which are tiny air sacs in the lungs. When we inhale, oxygen-rich air enters the lungs and diffuses across the alveoli into the capillaries, which are small blood vessels. At the same time, carbon dioxide, a waste product of metabolism, diffuses out of the capillaries into the alveoli and is exhaled.

Regulation of Blood pH

The lungs also play a role in regulating the pH of the blood. This is done by controlling the amount of carbon dioxide in the blood. Carbon dioxide is an acidic gas, so when the levels of carbon dioxide in the blood increase, the pH decreases and the blood becomes more acidic. Conversely, when the levels of carbon dioxide in the blood decrease, the pH increases and the blood becomes more alkaline.

Production of Surfactant

The lungs produce a substance called surfactant, which is essential for preventing the alveoli from collapsing. Surfactant is a mixture of proteins and lipids that lines the alveoli and reduces the surface tension of the air-liquid interface. This helps to keep the alveoli open, even when the lungs are fully deflated.

Defense Mechanisms

The lungs have several defense mechanisms that protect them from infection and injury. These mechanisms include:

* Mucus: The lungs produce mucus, a sticky substance that traps dust, pollen, and other particles.

* Cilia: The cells lining the airways are covered in cilia, which are tiny hair-like structures that move back and forth. This movement helps to move mucus and trapped particles out of the lungs.

* Alveolar macrophages: These cells are located in the alveoli and help to remove bacteria, viruses, and other foreign particles.

* Coughing and sneezing: These reflexes help to expel mucus and foreign particles from the lungs.

Other Functions

In addition to the functions listed above, the lungs also play a role in:

* Thermoregulation: The lungs help to regulate body temperature by exchanging heat between the air and the bloodstream.

* Water balance: The lungs help to regulate water balance by exchanging water vapor between the air and the bloodstream.

* Voice production: The lungs provide the power for說話. This is done by expelling air from the lungs through the larynx, which produces sound.