Pulmonary ventilation Flashcards
Main function of the lungs
Provide oxygen to the tissues and remove carbon dioxide
Main components of respiration
- ´Pulmonary ventilation: inflow and outflow of air between atmosphere and the lung alveoli
- Diffusion od oxygen and Carbon dioxide between alveoli and the blood
- Transport of oxygen and carbon dioxide in the blood and body fluids to and from the body´s tissue cells
- Regulation of ventilation and other facets of respiration
The lings can be expanded and contracted in two ways
- Downward and upward movement of diaphragm to lengthen or shorten the chest cavity
- Elevation and depression of the ribs to increase and decrease the anteroposterior diameter od the chest cavity
Muscles of inspiration
- External intercostals
- Sternocleidomastoid
- Anterior serrati
- Scaleni
Muscles of expiration
- Abdominal recti
- Internal intercostals
Normal pleural pressure at the beginning of inspiration
-5 centimeters of water, amount required to hold the longs open to their resting level
Pleural preassure during inspiration
-7.5 centimeters of water
To cause inward flow of air into alveoli during inspiration what has to happen
The pressure in the alveoli must fall below amospheric pressure (0)
Alveolar pressure during insporation
-1 centimeters of water
How much air it´s required for normal quiet inspiration
0.5 liter of air in 2 seconds
Alveolar pressure during expiration
+1, which forces the 0.5 liter to ve expired
Whats the transpulmonary pressure
difference between the alveolar pressure and the intrapleural pressure
Whats the recoil pressure
measure of the elastic forces in the lungs that tend to collapse the lungs at each instant of respiration
Whats lung compliance
measurement of lungs ability to expand and stretch
Total compliance of both lungs in the normal adult
200 mililiters of air per centimeter of water traspulmonary pressure, means that every time the transpulmonary pressure increases 1 centimeter of water the lung volume wil expand 200 mililiters after 10-20 seconds
The elastic forces of the lung tissue are determined by
elastin and collagen
What happens when there is no surfactant in the alveolar fluid
the fluid air surface tension elastic forces increase tremendously
Principle of surface tension
when water forms a surface with air the water molecules on the surface of the wateer have an especially strong attraction for one another.
What is the surface tension elastic force
The net effect to cause an elastic contractile force
Which cells secrete the surface active agent in water
Type II alveolar epithelial cells, constitute 10% of the surface area of the alveoli, these cells are granular with lipid inclusions
Most important phospholipids of the surfactant
Dipalmitoyl phosphatidylcholine, surfactant apoproteins and calcium ions
How does the phospholipids reduce the surface tension
They perform this function by not dissolving uniformly in the fluid lining the alveolar surface
Surface tension measurements
pure water 72 dynes/cm
normal fluids lining the alveoli without surfactant 50 dynes/cm
normal fluids with surfactant 5-30 dynes/cm
How do we calculate the amount of pressure generated in the alveoli
pressure= 2*surfacetension/redius of alveolus
What is respiratory distress syndrome of the newborn
Congenital defect in which the lungs do not secret the correct amount of surfactant and therefore the lungs have a tendency to colapse
Compliance of the combined lung-thorax system
110 mililiters of volume per centimeter of water pressure
The work of inspiration can be divided into three fractions
- Compliance work or elastic work required to expand lungs against the lung and chest elastic forces
- Tissue resistance wor required to overcome the viscosity of the lung and chest wall structures
- Airway resistance work required to overcome airway resistance to movement of air into the lungs
What is the tidal volume
volume of air inspired or expired with each normal breath, it amounts 500 mililiters in the average adult male
What is the inspiratory reserve volume
extra volume of air that can be inspired over and above the normal tidal volume when the person inspires with full force, usually 3000 mililiters
What is the expiratory reserve volume
is the maximum extra volume of air that can be expired by forceful expiration after the end of a normal tidal expiration, amount about 1100 mililiters
What is the residual volume
Volume of air remaining in the lungs after the most forceful expiration, averages 1200 mililiters
What is the inspiratory capacity
Equals the tidal volume plus the inspiratory reserve volume , its the capacity is the amount of air 3500 mililiters a person can breathe in, beginning at the normal expiratory level and distending the lungs to the maximun amount
What is the functional residual capacity
equals the expiratory reserve volume plus the residual volume, this capacity is the amount of air that remains in the lungs at the end of the normal expiration, about 2300 mililiters
What is the vital capacity
equals the inspiratory reserve volume plus the tidal volume plus the expiratory reserve volume
What is the total lung capacity
is the maximum volume to which the lungs can be expanded with the greatest possible effort 5800 mililiters, it is equal to vital capacity plus the residual volume
How much less are the volumes and capacities in woman than men
20-25%
