Respiratory System Part 2 Flashcards
Minute Ventilation
Total ventilation per minute
6000 mL/min = 500 ml/breath x 12 BPM
Minute ventilation = Tidal volume x Respiratory rate
Anatomical Dead Space
Amount of air that moves through the conducting zone
Not available for gas exchange
Typically 150mL
Alveolar Ventilation
Accounts for anatomical dead space
Alveolar ventilation = [Tidal volume – Dead Space] x Respiratory rate
4200 mL/min = [500 ml/breath – 150 ml/breath] x 12 BPM
Airway Resistance & Ventilation
Normally very small
Directly proportional to tube length
Inversely proportional to radius
Airway radii change in response to
– Physical
– Neural
– Chemical factors
Increasing radius
- Larger airway diameter = lower resistance to airflow
- Higher transpulmonary pressure
- Lateral traction
* As lungs expand, elastic tissue pulls small airways open, reducing
resistance.
Decreasing radius (Pathology)
- Decreased intrapleural pressure (less negative)
- Smooth muscle contraction (Bronchoconstriction)
Obstructive lung diseases: Increased airway resistance (e.g., asthma,
COPD, chronic bronchitis) due to airway narrowing
COPD
chronic obstructive pulmonary disease
Emphysema
destruction and collapse of the smaller airways
Chronic bronchitis
excessive mucus production in the bronchi, inflammation in the small airways
Asthma
constricted and/or inflamed airways
Anti-inflammatory drugs
Glucocorticoids
Reduce chronic inflammation
Bronchodilator drugs
Epinephrine agonists
Acetylcholine antagonists
Relax the airways
Dalton’s law
In a mixture of gasses pressure of each gas is independent
Hypoventilation vs hyperventilation
Increase in CO2 to alveolar ventilation vs decrease in CO2 to alveolar ventilation
Transport of Oxygen in Blood
Oxygen is transported in the blood bound to hemoglobin
Heme + Globin (polypeptide chains)
Heme (contains iron, binds oxygen)
Oxygen-Hemoglobin Dissociation Curve
As PO2 increases, hemoglobin saturation increases
At 100% in systemic arteries
Only 20% unloaded in tissues
Effect of Hemoglobin Binding to Oxygen
Hemoglobin greatly increases the oxygen carrying capacity of the blood
Bound oxygen doesn’t contribute to the PO2
Buffers
Buffers resist abrupt and large swings in pH
Release hydrogen ions if pH rises
Bind hydrogen ions if pH falls
Buffers in Blood pH
Bicarbonate resists abrupt and large swings in pH due to excess carbon dioxide
Release hydrogen ions if pH rises
Bind hydrogen ions if pH falls
Bohr effect
High CO2 at tissues helps offload O2 from Hb
Haldane effect
High O2 at lungs helps offload CO2 from Hb
