L63: Respiration Mechanics Flashcards
What is tissue respiration?
The aerobic metabolism in cells
What is breathing?
Gas exchange and the associated processes
What is the partial pressure of O2 at rest?
100 ± 2mmHg
What is the partial pressure of CO2 at rest?
40 ± 2mmHg
What are the gas exchange rates at rest?
~250mL/min O2, 200mL/min CO2
What are the gas exchange rates at 3mph walking?
~800mL/min O2, 750mL/min CO2
What are the gas exchange rates during severe exercise?
~5000mL/min O2, 6000mL/min CO2
What are the primary functions of the nasal cavities and paranasal sinuses?
- Filter;
- Warm;
- Humidify air;
- Detect smells.
What is the primary function of the pharynx?
Conduct air to the larynx
What are the primary functions of the larynx?
- Protects the opening of the trachea;
- Contains vocal cords.
What are the primary functions of the trachea?
- Filters air;
- Traps particles in mucus;
- Cartilage to keep airway open.
What are the primary functions of the bronchi?
- Filter air;
- Trap particles in mucus;
- Cartilage to keep airway open.
What are the primary functions of the lungs?
Responsible for air movement through volume changes during movements of ribs and diaphragm
What are the primary functions of the alveoli?
Sites of gas exchange between air and blood
What do the upper airways comprise of?
- Nasal cavities;
- Paranasal sinuses;
- Pharynx;
- Larynx;
- Trachea.
What is the overall role of the upper airways?
Humidify, filter and warm air through conduction TO the lungs,
What type of epithelium lines the upper airways?
Pseudo-stratified, ciliated, columnar epithelium
How does the production of mucus help to filter air in the airways?
Particles stick to the mucus and the mucus moves towards the mouth by beating cilia
What is the rate of ventilation at rest?
~6L/min (12x0.5L breaths)
What is the maximum rate of ventilation?
~160L/min (40x4L breaths)
What is C.O. at rest?
5L/min (70x70mL beats)
What is max C.O.?
25L/min (200x125mL beats)
During quiet breathing, inspiration is…
active
When you inspire, the diaphragm…
contracts and is pushed downwards
When you inspire, the intercostals…
pull ribs upwards and outwards
During quiet breathing, expiration is…
passive
When you expire, the diaphragm…
recoils into the original position
At rest, pressure inside and outside of the lungs is…
equal
When you inspire, pressure outside of the lungs is…
greater than inside of the lungs. Therefore, air moves IN.
After inspiration, pressure inside of the lungs is…
greater than outside of the lungs. Therefore, air then moves OUT (expiration).
Air moves from X pressure to Y pressure:
X: High, Y: Low
During strenuous breathing, inspiration is…
active
On strenuous inspiration…
- Greater contraction of the diaphragm;
- Greater contraction of the external intercostals (pull up);
- Accessory muscles are activated e.g. sternocleidomastoid
During strenuous breathing, expiration is…
active
On strenuous expiration
- Abdominal muscles are activated inc. internal and external oblique;
- Internal intercostal muscles (push down).
What type of breathing is most efficient and why?
Quiet:
- Small muscle effort;
What type of breathing is less efficient and why?
Strenuous:
- More muscles used;
- Accessory muscles can fatigue easily;
- Turbulent gas flow
What is functional residual capacity (FRC)?
The volume of air left in the lung at the end of expiration, during quiet breathing
How is FRC reached?
- Elastic recoil forces of the lung act to decrease lung volume;
- Outward recoil forces of the chest walls act to increase lung volume;
- @ FRC these are equal;
- Muscles are relaxed.
At the beginning of inspiration, recoil forces are…
disturbed and become unbalanced
FRC can be affected (reduced) by…
neuromuscular diseases
When measuring lung volumes, the 4 major results are:
- Forced vital capacity (FVC);
- Forced expiratory volume in 1 second (FEV1);
- Ratio of the above (FEV1/FVC);
- Average midmaximal expiratory flow (FEF25-75).
In a healthy individual, FEV1/FVC is:
> 70% (more than 70% of lung volume is expired in 1 second)
In patients with obstructive pulmonary disease, FEV1/FVC is:
<70%
In patients with restrictive pulmonary disease, FEV1/FVC is:
> 70%, because lung volume (FVC) is significantly (~80%) smaller
