Resp physiology Flashcards
(33 cards)
what are the functions of the lungs
- regulate blood pH
- produce sound
- gas exchange
- warm, humidify and clean air
- heat exchange
- olfactory organ
- metabolic/endocrine function
- pulmonary defence mechanisms
Conduction v respiratory zone
- conduction = brings air from outside in
- respiratory = active resp and gas exchange
Organisation of bronchioles
Bronchioles
Terminal bronchioles
Respiratory bronchioles
Alveolar ducts
Aveoli
Types of alveolar cells
Type I - involved in gas exchange
Type II - secrete surfactant to reduce surface tension
Macrophages - remove debris and foreign cells
Ficks Law of diffusion
shorter distance and greater surface area increases the rate of diffusion
what do pleura do
- lubrication
- surface tension
- division
Volume/pressure relationship
when volume increases > pressure decreases
Steps of inspiration
- inspiratory muscles contract
- thoracic cavity vol increases
- intrapulmonary pressure decreases (-1mmHg)
- air flows in until equalises
Is expiration (quiet) passive or active
passive > muscles relax and diaphragm rises, lungs naturally want to recoil
what is tidal volume
the amt of air in or out of lungs with each cycle (usually 400-500ml)
what keeps the lungs open
transpulmonary pressure
- pressure difference across whole lung and all spaces
what muscles does force inspiration recruit
scalenes
serratus anterior
pec major and minor
SCM
what muscles does forces expiration recruit
ext and int obliques
transversus abdominis
rectus abdominis
what physical factors influence ventilation
- airway resistance
- lung compliance and recoil
- alveolar surface tension
how does airway resistance influence ventilation
- friction from air moving against airways
- resistance decreases as moving through the airways
what is dynamic small airway closure
- intrapleural space pressures into small airway to stop any more air flowing out (stops all air leaving lungs)
when does early small airway closure occur
asthma
- because of increased small airway resistance, loss of pressure
how does lung compliance influence ventilation
- ability for lungs to be stretched and rebound
having the correct balance allows for correct ventilation to occur
how does alveolar surface tension influence ventilation
- without surfactant alveoli would want to collapse into the bigger ones
- surfactant lowers the elastic recoil and stabilises alveoli
if we didn’t have it we would have to try much harder to inflate our lungs
What are the forces keeping alveoli open
- transmural pressure gradient
- pulmonary surfactant
- alveolar interdependence
what are the force promoting alveolar collapse
- elasticity of stretched connective tissue
- alveolar surface tension
what is external respiration
exchange of oxygen and carbon dioxide between blood and alveoli
what should the ventilation/perfusion be
V/Q=1
characteristics of pulmonary circulation
- low pressure, low resistance
- short
- branches immediately
- passive factors play important role
- receives all cardiac output
