alveolar dead space

(noun)

Alveolar space that can no longer contribute to gas exchange due to damage or scarring.

Related Terms

Examples of alveolar dead space in the following topics:

  • Pressure Changes During Pulmonary Ventilation

    • It is defined as $VA=(Tidal Volume-Dead Space Volume)* Respiratory Rate$
    • It is defined as $VD=DeadSpaceVolume*Respiratory Rate$.
    • This is most apparent in changes of the dead space volume.
    • Breathing through a snorkeling tube and having a pulmonary embolism both increase the amount of dead space volume (through anatomical versus alveolar dead space respectively), which will reduce alveolar ventilation.
    • Differentiate among the types of pulmonary ventilation: minute, alveolar, dead space

  • Alveoli

    • Type I (Squamous Alveolar) cells: These form the structure of an alveolar wall.
    • The alveoli are the site of alveolar ventilation, and are not normally considered dead space.
    • However, alveoli that are injured and can no longer contribute to gas exchange become alveolar dead space.
    • Physiological dead space is the sum of normal anatomical dead space and alveolar dead space, and can be used to determine the rate of ventilation (gas exchange) in the lungs.
    • When any type of dead space increases, the rate of ventilation in the lungs will decrease.

  • Trachea

    • The trachea is also considered a part of normal anatomical dead space (space in the airway that isn't involved in alveolar gas exchange) and its volume contributes to calculations of ventilation and physiological (total) dead space.
    • It is not considered alveolar dead space, a term that refers to alveoli that don't partake in gas exchange due to damage or lack of blood supply.

  • Lungs

    • The pleural cavity is the fluid-filled space between the parietal and visceral pleura, and provides room for the lung to expand during inhalation.
    • Too low perfusion (and a higher ratio) indicates alveolar dead space, while too low ventilation (and a lower ratio) indicates a shunt, which is a lack of air supply relative to perfusion.

  • Functional Anatomy of the Respiratory System

    • It is defined as tidal volume minus dead space (the space in the lungs where gas exchange does not occur) times the respiratory rate.
    • Dead Space Ventilation (VD): The amount of air per unit of time that doesn't reach the alveoli.
    • It is defined as volume of dead space times the respiratory rate.
    • Dead space is any space that isn't involved in alveolar gas exchange itself, and it typically refers to parts of the lungs that are conducting zones for air, such as the trachea and bronchioles.
    • If someone breathes through a snorkeling mask, the length of their conducting zones increases, which increases dead space and reduces on alveolar ventilation.

  • Bronchi and Subdivisions

    • The bronchi and bronchioles are considered anatomical dead space, like the trachea and upper respiratory tract, because no gas exchange takes place within this zone.
    • Each terminal bronchiole then gives rise to several respiratory bronchioles, which go on to divide into two to 11 alveolar ducts.
    • There are five or six alveolar sacs associated with each alveolar duct.
    • Like the trachea, the bronchi and bronchioles are part of the conducting zone, so they moisten and warm air and contribute to the volume of anatomical dead space.

  • Dead Space: V/Q Mismatch

    • There are two types of V/Q mismatch that produce dead space.
    • Dead space is characterized by regions of broken down or blocked lung tissue.
    • Dead space is created when no ventilation and/or perfusion takes place.
    • Anatomical dead space, or anatomical shunt, arises from an anatomical failure, while physiological dead space, or physiological shunt, arises from a functional impairment of the lung or arteries.
    • Compare and contrast anatomical and physiological dead space and their role in V/Q mismatch

  • Macrophages

    • Resident macrophages become adapted to perform particular functions in different organs; so that brain macrophages (microglia) are very different from alveolar macrophages of the lung, Kupffer cells of the liver, or the largest tissue macrophage population, those lining the wall of the gut.
    • The macrophage then has the task of clearing both the dead pathogens and the dead neutrophils.

  • Gas Exchange across the Alveoli

    • The RQ is a key factor because it is used to calculate the partial pressure of oxygen in the alveolar spaces within the lung: the alveolar PO2 (PALVO2).
    • When the RQ is known, the partial pressure of oxygen in the alveoli can be calculated: alveolar PO2 = inspired PO2−((alveolar PO2)/RQ)
    • More specifically, alveolar PO2 is higher in the alveoli (PALVO2=100mmHg) than blood PO2 in the capillaries (40mmHg).
    • At the same time, alveolar PCO2 is lower (PALV CO2=40mmHg) than blood PCO2 (45mmHg).

  • The Book of the Dead

    • The New Kingdom saw the Book of the Dead develop and spread further.
    • There was no single Book of the Dead, and works tended to vary widely.
    • Books were often prefabricated in funerary workshops, with space left for when the name of the deceased would be written in later.
    • During the New Kingdom, the Book of the Dead was typically written in cursive hieroglyphs.
    • Describe what the Book of the Dead was and explain its use in Ancient Egypt