Ventilation and Lung Volumes

imissyou419's version from 2017-02-01 23:51


Question Answer
Spirometry definition, how does it work?a method to measure lung volumes; spirometer consists of a upside down bell filled with air hanging in a liquid. Subject breathes air from bell and movement of bell (up with exhalation and down with inhalation) is recorded with a pen on a moving chart
Tidal volumevolume of air inhaled with each breath
Vital capacityvolume of air that can be forcibly exhaled after a maximal inspiration
Residual volumevolume of air remaining in the lungs after a maximal expiration (cannot be measured with spirometer)
Functional residual capacity, what makes it up?volume of air remaining in the lung at the end of a normal expiration; it is the expiratory reserve volume + residual volume
Pulmonary Ventilation (equation)Tidal volume x respiration frequency; volume of air inhaled per minute (not all this participate in gas exchange)
Inspiratory Reserve Volumevolume of air that can be forcibly inhaled following a normal inspiration
Expiratory Reserve Volumevolume of air that can be forcibly exhaled following a normal expiration
During exercise, what volume increases?inspiratory and expiratory reserve volumes become smaller as tidal volume increases
Maximal voluntary ventilation/maximal breathing capacityvolume of air that can be moved into and out of the lung in one minute by voluntary effort (normal person range 125-170 L/min)
Total lung capacityvolume of air in the lungs at the end of maximal inspiration
FEV-1fraction of vital capacity expired in 1 sec;
Normal - 80% of VC expired in 1 sec,
In restrictive diseases (pulmonary fibrosis) - VC is reduced but FEV-1s normal or increased.
In obstructive diseases (asthma), VC is the same but FEV-1s is reduced (like breathing through straw due to constricted airways so take longer to exhale vital capacity)
What volumes cannot be measured with a spirometer?Total lung capacity, residual volume, functional residual capacity (can use the Helium-Dilution method)
What makes up the inspiratory capacity?inspiratory reserve volume + tidal volume
What makes up the vital capacity?inspiratory reserve volume + tidal volume + expiratory reserve volume
Helium dilution methoduses a "closed circuit". The subject, after normal expiration, is connected to a spirometer containing a known concentration of He. He is insoluble in blood (cant diffuse across blood gas barrier). After some breathes, [He] in the spirometer and lung become the same. Since no He has been lost the amount of He present before equilibrium equals the amount after equilibrium
How do you find FRC? (equation)C1V1 = C2(V1+V2) where V2 = FRC
Anatomic Deadspacevolume of air remaining in the conductive zone (no alveoli = do not participate in gas exchange)
Alveolar ventilationpulmonary ventilation - dead space ventilation; volume of air entering the respiratory zone per minute
Physiological/total dead spacevolume of air entering the lung that does not participate in gas exchange
How is physiological deadspace different from anatomical deadspace?in normal person, no difference but in disease conditions, inhaled air may enter nonfunctional alveoli so the volume entering those areas contribute to total dead space or disease inhibiting blood flow so decrease gas exchange and add to total dead space
When is alveolar ventilation reduced when pulmonary ventilation stays the same?shallow quick breaths (because air is not going to alveolar and instead more goes to dead space)
Bohr equationVD/VT = (PACO2-PECO2)/PACO2 (assumption: all exhaled CO2 comes from the site of gas exchange/alveolar gas); gas exchange of CO2 is very efficient so Pa can be substituted for PA
What happens if you increase deadspace while maintaining the same alveolar ventilation, respiratory rate, arterial PCO2?increase tidal volume (take deep breathes to get air to alveoli), decrease exhaled PCO2 (more dead space so diluted CO2)
What happens to inspired air?water vapour added and is diluted with air present in the lung (FRC)
What does the expired air consists of?mixture of alveolar air and air in anatomical deadspace
What has higher partial pressure of O2? arterial or alveolar?alveolar because a small amount of venous blood reaches arteries without going through pulmonary capillaries

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