Week 8 Flashcards
4 steps in the transport of O2
- Pulmonary ventilation
- Pulmonary diffusion
- Gaseous transport
- Capillary diffusion
Define external and internal respiration
External respiration: Pulmonary ventilation and diffusion
Internal respiration: Gas exchange between blood and tissues
Define alveoli
Site of gas exchange between lung tissue and blood
What are the 2 zones of ventilation
Conducting
Transitional and respiratory
Conducting zone function and location
Trachea and terminal bronchioles
- Considered anatomic dead space, contains no alveoli - Functions: air transport, warming, particle filtration
Transitional and respiratory zone and function
Bronchioles, alveolar ducts and alveoli
- Functions: Gas exchange, surfactant production and molecule activation - Largest area, occupies 2.5 - 3L
Define Fick’s law of diffusion
Fick’s Law describes the relationship between the rate of diffusion and the three factors that affect diffusion.
States that a gas diffuses through a sheet of tissue at a rate:
1. Directly proportional to the tissue area, a diffusion constant and the pressure differential of the gas on each side of the membrane
2. Inversely proportional to tissue thickness
sequence of events in inspiration
Sequence of events:
1. Inspiratory muscles contract
2. Thoracic cavity volume increases
3. Lungs stretched; intrapulmonary volume increases
4. Intrapulmonary pressure drops
Air flows into lungs down its pressure gradient until intrapulmonary pressure is 0
Sequence of events in expiration
- Inspiratory muscles relax
- Thoracic cavity volume decreases
- Elastic lungs recoil passively
- Intrapulmonary pressure rises
Air flows out of lungs down its pressure gradient until intrapulmonary pressure is 0
When do the intercostals contract, and when do they relax
Contract = inspiration Relax = expiration
Define Tidal Volume (TV)
Air moved during the inspiratory or expiratory phase of each breathing cycle
Define Inspiratory reserve volume (IRV)
Inspiring as deeply as possible following a normal inspiration
Expiratory reserve volume (ERV)
After a normal exhalation, continuing to exhale and forcing as much air as possible from the lungs
Forced vital capacity (FVC)
Total volume of air voluntarily moved in one maximal breath
Define residual lung volume
Air volume remaining in the lungs after a forced maximal exhalation
What does dynamic ventilation depend on
- Maximum ‘stroke volume ‘of the lungs (FVC)
Speed of moving a volume of air (breathing rate)
Define anatomic dead space
Air in each breathe that does not enter alveoli and participate in gaseous exchange with blood
Define alveolar ventilation
portion of inspired air reached the alveoli and participating in gas exchange
Define the ventilation-Perfusion (V-P) ratio
the ratio of alveolar ventilation to pulmonary blood flow
Define physiologic dead space
air that is physiologically inaccessible to the body
What 2 things can cause alveoli to not function properly
- Underperfusion of blood
Inadequate ventilation relative to alveolar surface
Define hyperventilation
An increase in pulmonary ventilation that exceeds the O2 consumption and CO2 elimination needs of metabolism
Define dyspnea
An inordinate shortness of breath or subjective distress in breathing
Define vaslalva manuerver
Closing the glottis following a full inspiration while maximally activating the expiratory muscles, creating compressive forces that increase intrathoracic pressure above atmospheric pressure
