Ventilation and Compliance Flashcards
(28 cards)
What is ANATOMICAL DEAD SPACE?
1) Volume of Gas in the Conducting Airways
2) This Gas is Not Available for Exchange
3) Volume = 150ml
What is the MAXIMUM VOLUME of air that can be VOLUNTARILY EXHALED following a MAXIMUM INSPIRATION?
(Forced) Vital Capacity
Tidal Volume + Inspiratory Reserve Volume + Expiratory Reserve Volume
3-5 litres in Healthy Adults
*Varies with Age, Gender, Height, Mass and Ethnicity
What is the VOLUME of air breathed IN or OUT of the lungs at EACH BREATH?
Tidal Volume
What are the TWO TYPES of VENTILATION?
1) Pulmonary (Minute) Ventilation
2) Alveolar Ventilation
What is PULMONARY (MINUTE) VENTILATION?
Total Air Movement Into and Out of the Lungs
*Little Functional Significance
What is ALVEOLAR VENTILATION?
Volume of Fresh Air, per unit of time, Reaching the Alveoli; Available for Gas Exchange
(Tidal Volume - Anatomical Dead Space) x Respiratory Rate
What are the TWO TYPES of CELL that make up the ALVEOLAR WALLS and what are their FUNCTIONS?
1) Type I Pneumocytes - Permit Gas Exchange
2) Type II Pneumocytes - Secrete Surfactant
What is the PURPOSE of SURFACTANT FLUID?
1) < Surface Tension on Alveolar Surface Membranes
2) Prevents Alveoli from Collapsing
How does SURFACTANT FLUID BENEFIT breathing?
1) > Lung Compliance
2) < Tendency for Recoil
3) > Ease of Breathing
At HOW MANY WEEKS of GESTATION does surfactant production begin?
25 Weeks Gestation
When is surfactant production COMPLETE and WHY is this IMPORTANT?
By 36 Weeks Gestation
Premature babies (i.e. born before 36 weeks) Have Not Yet Produced Sufficient Amounts of Surfactant to Keep their Alveoli Open
Suffer from Infant Respiratory Distress Syndrome (IRDS)
What is COMPLIANCE?
Change in Volume Relative to Change in Pressure
Stretchability of the Lungs
Is INSPIRATION an ACTIVE or a PASSIVE process?
Active
Is EXPIRATION, normally, an ACTIVE or a PASSIVE process?
Passive
How is the WORK of BREATHING RECOVERED during passive expiration?
Elastic Recoil of the Lungs
In EMPHYSEMA, is the WORK of BREATHING increased or decreased?
Increased
- Due to Loss of Elastic Fibres Surrounding the Alveoli; Preventing Recoil and Prolonging Expiration
- Obstructive Disease
In PULMONARY FIBROSIS, is the WORK of BREATHING increased or decreased?
Increased
- Due to Inert Fibrous Tissue Which > the Effort Required for Inspiration by < Lung Compliance
- Restrictive Disease
Where are the ALVEOLI BEST VENTILATED?
Base of the Lung
*Alveolar Ventilation Declines with Height from the Base to the Apices
Where is COMPLIANCE BEST in the LUNGS?
Base of the Lung
- Alveoli at the Apex are More Inflated due to Functional Residual Capacity
- Alveoli at the Base are Compressed Between the Weight of the Lung and Diaphragm; Hence More Compliant on Inspiration
What is OBSTRUCTIVE LUNG DISEASE?
Obstruction of Air Flow, due to > Airway Resistance; Especially on Expiration
Exs) COPD; Asthma; Bronchiectasis; Lung Cancer
What is RESTRICTIVE LUNG DISEASE?
1) Restriction of Lung Expansion
2) Loss of Lung Compliance
Exs) Pulmonary Fibrosis; Pulmonary Oedema; Pneumonia; Pneumothorax; Infant Respiratory Distress Syndrome (IRDS)
What CANNOT be DIRECTLY MEASURED via SPIROMETRY?
1) Functional Residual Capacity (Expiratory Reserve + Residual Volume) 2) Residual Volume
What would be the PREDICTED NORMAL FORCED EXPIRATORY VOLUME in 1 SECOND (FEV1) for healthy males?
4.0L
What would be the PREDICTED NORMAL FORCED VITAL CAPACITY (FVC) for healthy males?
5.0L
