Ventilation Flashcards
What is the function of ventilation?
- Provide is to provide O2 and remove CO2.
How is ventilation function achieved
The function is achieved by:
- Pulmonary ventilation,
- Regulation of ventilation,
- Matching of pulmonary blood flow to alveolar ventilation,
- Movement of O2 and CO2 between alveoli and blood,
- Transport of O2 and CO2 in blood and body fluids.
What are the non-respiratory function?
Expulsion of foreign bodies and defence against infection/disease
What is alveolar ventilation?
Rate at which new area reaches of alveoli.
What is dead space?
It is air breathed in but never reaches gas exchange areas but fills respiratory passages eg, nose, pharynx and trachea.
How do you calculate alveolar ventilation
Respiratory rate x (Volume (total) - Volume in dead space)
Name the two ways in which the lungs can be expanded and contracted?
- Downward and upward movement of diaphragm to lengthen or shorten chest cavity
- Elevations and depression of the ribs increase anteroposterior diameter of the chest cavity.
What are the most important muscles in raising the ribs?
- External intercoastal,
- Sternocleidomastoid (lifts the sternum upwards)
- Anterior Serrati
- Scaleni
What are the important muscles that lower the rib cage?
Abdominal recti and internal intercostals
Describe the static properties of lungs
- The lung is an elastic structure collapses like a balloon when no forces to keep inflated.
- Lymphatic drainage of excess fluid between lung pleural membrane and pleural surface of thoracic wall leads to a suction effect.
What is the intrapleural pressure?
The pressure of fluid in thin space between lung and chest wall pleura - creates negative pressure
Describe the pressure changes that occurs during ventilation
The pressure decreases during inspiration which draws in air in. Then during expiration the pressure increases which forces air out. When the glottis is open and no air is flowing then the pressure in all parts of the respiratory tree is equal to atmospheric pressure.
What is the transpulmonary pressure?
The pressure difference between the alveoli and that on the outer surfaces of the lung. Therefore it is a measure of the elastic forces that then to collapse the lungs.
Why is energy needed for respiration?
It is required by:
- Contract the muscles of inspiration,
- Stretch elastic elements,
- Overcome airway resistance,
- Overcome frictional forces arising from the viscosity of the lung and chest wall
- Overcome inertia of air and tissues.
Airflow is determined by what?
Change of pressure divided by the resistance.