Lecture 2 Flashcards
What are the 3 functions of surfactant
- reduces surface tension in the alveolar lining fluid, (reduces the tendency for the alveolus to collapse).
- increases lung compliance.
- prevents transudation of fluid into alveoli -> less negative pressure in the interstitial space, therefore lower hydrostatic pressure gradient between pulmonary capillary and interstitial space
Where can e observe a decrease in lung compliance
↓ Lung compliance: Interstitial edema Pulmonary edema ↓ ventilation of lung for an extended period Diseases causing pulmonary fibrosis
Where can e observe a increase in lung compliance
↑ Lung compliance
Age
Emphysema
Why chronic bronchitis and emphysema have a hyperinflation?
Obstructive lund mx. -> emphysema -> incr lung compli, the tethering (elastic fibers in the lung) gets destroyed -> end up getting stretched more, more floppy -> FRC gett more larger -> hyperinflated
Chronic bronchitits (part of COPD)-> increased rsistance -> not bc of elasticity, but air trapping, to espirate you have to push harder -> increase FRC but the mecanism is diff between emphysema and chron bronc
What is resistance to airflow
Resistance to airflow (Raw) is equal to the pressure difference between alveolar and atmospheric pressure (AP) divided by airflow.
Raw= (Palv-Patm)/Flow
Name 4 Factors increasing airway resistance:
Reduced lung volumes Increased bronchial motor tone Reduced airway caliber Increase in density and viscosity of inspired air
Resistance =8 η L/πr4
T/F
Major airway resistance is in the small airways
Major resistance NOT in the small airways - total cross-sectional area increases as descend the tracheo-bronchial tree - ↓↓ drop in flow.
Where is the EPP in healthy & emphysema
Heathly: at EPP there is cartilage
Emphys: at EPP no cartilage, happens deeper, further in the branching
Respiratory rhythm altered by inputs from the pons:
describe
Apneustic center regulates the length and depth of inspiration.
Pontine respiratory group (PRG) regulates apneustic center & medullary rhythmicity area.
T/F
Cerebral cortex can override “automatic” control of breathing for voluntary activities i.e. deep breathing, breath holding, singing etc.
T
T/F
Inputs to brainstem from chemoreceptors, baroreceptors only regulate breathing
Inputs to brainstem from chemoreceptors, baroreceptors, and stretch receptors (lungs), irritant receptors (airways), proprioceptors (joints & muscles) and emotional input (limbic system) regulate breathing
where are the central chemoreceptor
Located just below the ventrolateral surface of the medulla
the central chemoreceptor respond to
Respond to H+ dissolved in the cerebrospinal fluid (CSF)
T/F
O2 and CO2 diffuses through the blood-brain barrier which separates the CSF & arterial blood
F
Only CO2 diffuses through the blood-brain barrier which separates the CSF & arterial blood
T/F
In CSF, CO2 cannot combines with H2O and forms H+ & HCO3-
F
Yes it can
