25. Mechanics of Ventilation 1 Flashcards
What is external respiration?
Exchange of oxygen and carbon dioxide between the body and the external environment
What is internal respiration?
Uptake, utilisation of oxygen by cells
Release of carbon dioxide
What is gas pressure?
Force that the gas exerts on the walls of its container
State Boyle’s law
For a fixed mass of enclosed gas at constant temperature, the product of the pressure and volume remains constant
What effect does the negative intrathoracic pressure have?
Creates a vacuum
Describe the events of inspiration
- Inspiratory muscles contract
- Diameter of the thoracic cage increases
- Intrapleural pressure becomes more negative
- Transmural pressure increases and causes alveoli to open
- Intra-alveolar pressure falls relative to atmospheric pressure
- Air flows down pressure gradient into alveoli
What are the primary respiratory muscles?
Diaphragm
External intercostals
What are the accessory muscles?
Scalenes
Sternomastoid
In what diseases might accessory muscles be overactive?
Chronic bronchitis
Asthma
Emphysema
Name the airway muscles
Laryngeal
Pharyngeal
Genioglossus
TV
Tidal Volume
IRV
Inspiratory Reserve Volume
IC
Inspiratory Capacity
ERV
Expiratory Reserve Volume
RV
Residual Volume
FRC
Functional Residual Capacity
VC
Vital Capacity
TLC
Total Lung Capacity
What is FEV1?
Forced Expiratory Volume in one second
Expressed as a percentage of FVC
80% in a healthy person
Effect of Obstructive Disease on Spirometer
Increased RV
Decreased FEV1
Decreased FEV1/FVC ratio
Effect of Restrictive Disease on Spirometer
Decreased TLC
Decreased FEV1
Decreased FVC
