Q:

Alveoli serve what function in the lungs?

A:

Pulmonary alveoli are the tiny sacs inside the lungs that fill with air with each breath and facilitate the exchange of gas with the blood. According to HowStuffWorks, the oxygen concentration in the alveoli is high, relative to that of the surrounding tissues, which permits easy passage to the blood.

With each breath, air from outside the body is pulled down the trachea and into the lungs through a branching network of pipes called bronchioles. These bronchioles get progressively smaller until they terminate in the alveolar sacs. The sacs have very thin walls, and they are heavily vascularized, according to HowStuffWorks. Their thin walls permit oxygen to cross over into the blood that is delivered by the pulmonary arteries and permits waste gasses like carbon dioxide to escape into the air in the sac.

Once the exchange takes place, a process that lasts just fractions of a second per cycle, the waste air is expelled with exhalation and the oxygen-rich blood is free to pass back to the heart via the pulmonary veins. This gas-exchange process in the lungs takes place exclusively within the alveoli and is known as external respiration, as opposed to the internal respiration that takes place across the membrane of individual cells, notes HowStuffWorks.


Is this answer helpful?

Similar Questions

  • Q:

    What is the function of the bronchioles?

    A:

    Bronchioles are tiny airways that carry oxygen to alveoli, or air sacs, in the lungs and help stabilize breathing in the respiratory system, according to About.com. Bronchioles are lined with smooth muscular walls that constrict or expand to regulate airflow and prevent irritants from passing further along the respiratory tract.

    Full Answer >
    Filed Under:
  • Q:

    What is the function of pleural fluid?

    A:

    Pleural fluid prevents friction between the lungs and the chest cavity during respiration, and is found in a thin space between two layers of tissue. The tissues surrounding the lungs produce the fluid that rhythmically ebbs and flows in the small pleural space.

    Full Answer >
    Filed Under:
  • Q:

    What is the main function of the heart?

    A:

    The main function of the heart is to pump blood to the lungs to be saturated with oxygen, and then pump it out into the body to supply the cells with oxygen. The heart, along with the blood vessels, make up the cardiovascular system.

    Full Answer >
    Filed Under:
  • Q:

    What is the function of the left atrium?

    A:

    The left atrium serves as a vessel for blood coming from the lungs and a pump to deliver blood to other parts of the heart, according to Healthline. Oxygen-rich blood from the lungs goes to the left atrium via the pulmonary vein.

    Full Answer >
    Filed Under:

Explore