Respiratory Physiology Flashcards
what is internal respiration
intracellular mechanisms which consume O2 and produce CO2
what is external respiration
sequence of events that lead to the exchange of O2 and CO2 between external environment and cells of the body
four steps of external respiration
- ventilation between atmosphere and alveoli
- O2 and CO2 exchange between alveoli and blood
- transport of O2 and CO2 between lungs and tissues
- exchange of O2 and CO2 between blood and tissues
what is ventilation?
mechanical process of moving air between atmosphere and alveoli
pressure change for ventilation to occur? (boyle’s law)
intra alveolar pressure must be less than atmospheric pressure
2 forces that hold thoracic wall and lungs close
- intrapleural fluid cohesiveness
2. negative intrapleural pressure (lungs force out, chest forced in)
muscles of inspiration and function
- external intercostal muscles, elevates ribs and sternum
- diaphragm, lowers to increase size of thoracic cavity
expiration - passive of active?
passive
what abolishes the transmural pressure gradient?
pneumothorax
what causes lungs to recoil?
- elastic connective tissue
2. alveolar surface tension
what is alveolar surface tension?
water and air molecules are attracted in the alveoli, which produces a force that resists stretching
what is surfactant and what does it do?
- it is secreted by type II alveoli
- it lowers alveolar surface tension, as it mixes with water molecules lining the alveoli
What does LaPlace’s law state?
smaller alveoli have a higher tendency to collapse
what is alveolar interdependence?
if an alveolus begins to collapse, surrounding stretch to pull the collapsing one open
what does parasympathetic stimulation do to the airways?
causes bronchoconstriction