What is the inspiratory reserve volume?
Air that can still be breathed in after normal inspiration
What is the tidal volume?
Air that moves into lung with quiet inspiration, typically 500mL
What is the expiratory reserve volume?
Air that can still be breathed out after normal expiration
What is the residual volume?
Air in the lung after maximal expiration
Cannot be measured on spirometry
What is the inspiratory capacity?
IRV + TV
What is the functional residual capacity?
Volume of air in lung after normal expiration
What is the Vital capacity?
Maximum volume of gas that can be expired after maximal inspiration
TV + IRV + ERV
What is the total lung capacity?
Volume of gas present in lungs after maximal inspiration
IRV + TV + ERV + RV
What lung volume(s) cannot be measured directly in a spirometer?
Any capacity with RV (including FRC, TLC) cannot be measured
What is physiological dead space?
Anatomic dead space of conducting airways and functional dead space in alveoli
What is the largest contributor of functional dead space?
Apex of health lung
How to calculate dead space
Vd = Vt x (PaCO2-PeCO2)/PaCO2
How to calculate alveolar ventilation?
Va = CO2 production/PACO2
As ventilation increases, PACO2 decreases
How to calclate minute ventilation?
(Vt-Vd) x RR
What are the tendencies of the lung and chest wall to do if there are no opposing forces?
Lung to collapse
Chest wall to spring outward
What happens to lung and chest wall pressures at FRC?
Inward pull of the lung is balanced by outward pull of chest wall
What is the system pressure at FRC?
What are the following pressures at FRC:
Airway and alveolar pressure = 0
Intrapleural pressure = negative (prevent pneumothorax
What is compliance of the lung?
Change in lung volume for a given change in pressure
What conditions decrease compliance?
What conditions increase compliance?
Emphysema, normal aging
What is the structure of hemoglobin?
2 alpha and 2 beta (4 polypeptide subunits)
What are the two forms of hemoglobin and their affinity for O2?
Taut (low affinity)
Relaxed (high affinity)
What exhibits positive cooperativity and negative allostery?
What favors taut form over relaxed form? (5)
1. Increased Cl-
2. Increased H+
3. Increased CO2
4. Increased 2,3-BPG
5. Increased temperature
What happens to the dissociation curve when taut form is favored?
Right shift, causing increased in O2 unloading
What is the structure of fetal hemoglobin? How is it different from adult form?
2 alpha 2 gamma subunits
Lower affinity for 2,3-BPG (higher affinity for O2)
What is methemoglobin? What does it have affinity for?
Oxidized form of hemoglobin (ferric, Fe3+)
Does not bind O2 as readily, but has increased affinity for cyanide
What is the normal state of iron in hemoglobin?
To treat cyanide poisoning, nitrites are used. What is the mechanism for its action?
Oxidize hemoglobin to methemoglobin, which binds to cyanide, allowing cytochrome oxidase to function