Flashcards in Gas Exchange (3) Deck (19)
What is pulmonary ventilation?
The volume of air breathed in and out per minute
What is alveolar ventilation?
The volume of air exchanged between atmosphere and alveoli per minute (represents new air available for gas exchange with blood)
What is anatomical dead space?
Inspired air that remains in the airways where it is not available for gas exchange
What increases pulmonary ventilation and what is more advantageous?
Increase depth (tidal) and rate . Due to dead space , deep breathing is more advantageous.
What 2 things does the transfer of gases between the body and atmosphere depend on and explain them?
Ventilation- the rate at which gas is passing through the lugs
Perfusion-the rate at which blood is passing through the lugs
What is alveolar dead space?
Ventilated alveoli which are not adequately perfused with blood
What is physiological dead space?
Anatomical dead space and the alveolar dead space
What matches airflow to blood flow?
Local controls act on smooth muscles of airways and arterioles
What 4 factors influence the rate of gas exchange across the alveolar membrane?
1) Partial pressure gradient of O2 and CO2
2) Diffusion coefficient for O2 and CO2
3) Surface area of alveolar membrane
4) Thickness of alveolar membrane
What is Daltons law of partial pressure?
The total pressure exerted by a gaseous mixture = sum of the partial pressures of each individual component in the gas mixture
What determines the pressure gradient for a gas?
Partial pressure of that gas
What is the pressure of inspired air?
atmospheric pressure - water pressure
What is the diffusion coefficient?
The solubility of gas in the membrane
Which gas has a higher diffusion coefficient?
The diffusion coefficient for CO2 is 20 times that of O2
What is Fick's law of diffusion?
The amount of gas that moves across a sheet of tissue in unit of time is proportional to the area of the sheet but inversely proportional to its thickness
How does surface area and a thin membrane affect gas exchange ?
Lungs provide a very large surface area with thin membranes to facilitate effective gas exchange. Airways divides repeatedly and small airways form out pockets to increase surface area
What are the non-respiratory functions of respiratory system?
1) route for water loss and heat elimination
2)Enhances venous return
3)help maintain normal acid-base balance
4) Enables speech, singing
5)Defends against inhaled foreign matter
6)Removes,modifies,activates/inactivates various materials passing through the pulmonary circulation
7)nose serves as the organ of smell
What is partial pressure?
The pressure that gas that would exert if it occupied the total volume for the mixture in the absence of other components