Respiratory Physiology Part 2 Flashcards
muscles of breathing
diaphragm
abdominals
internal intercostals
diaphragm effect on breathing
when diaphragm contracts the abdominal contents are pushed down and ribs are lifted upward and outward
increases intrathoracic volume
diaphragm increase intrathoracic volume which in turn causes ___
decreases intrathoracic pressure and initiates flow of air into lungs
abdominals on breathing
compress abdominal cavity and push diaphragm up
internal intercostals on breathing
pulls rib downward and inward
function of expiratory muscles during exercise or disease
during an increase in airway resistance these muscles aid in the expiratory process
compliance
- distensibility of the system
- how volume changes as a result of pressure change
- inversely correlated with elastance
measuring lung compliance
requires simultaneous measurement of lung pressure and volume
transmural pressure
pressure across a structure
pressures equal to atmospheric pressure
zero
pressure higher than atmospheric pressure
positive
pressures lower that atmospheric pressure
negative
Hysteresis
term used to describe the difference between inspiratory and expiratory compliance. Lung volume at any given pressure during inhalation is less than the lung volume at any given pressure during exhalation. Hysteresis is present in both static and dynamic lung compliance curves.
why are inspiration and expiration curves different?
hysteresis
the intermolecular forces between liquid molecules lining the lung are much stronger than the forces between liquid and air molecules
pneumothorax
sharp object punctures the intrapleural space
intrapleural pressure = atmospheric pressure
2 consequences of pneumothorax
lung collapse
chest wall expands
Volume is FRC
lungs wants to collapse
chest wall wants to expand
The combined lung and chest wall system NEITHER has a tendency to collapse NOR to expand
Volume is less than FRC
forced expiration
- there is less volume in the lungs and the collapsing force of the lungs is smaller
- expanding force on chest wall is greater
combined system “wants to expand”
Volume is greater than FRC
subject inspires
- more volume in the lungs / collapsing force is greater
- expanding force in chest wall is smaller
combined lung and chest wants to collapse
diseases of lung compliance
emphysema
fibrosis
Emphysema
increase lung compliance
COPD - loss of elastic fibers
Fibrosis
decreased lung compliance
restrictive disease
Emphysema effect on Volume is FRC
tendency for lungs to collapse is less than the tendency for the chest wall to expand
How to balance out emphysema effect on Volume is FRC
volume must be added to increase their collapsing force
needs higher FRC
Fibrosis effect on Volume is FRC
tendency of the lungs to collapse is greater than the tendency of the chest wall to expand
How to balance out fibrosis effect on Volume is FRC
the lung and chest wall seak lower FRC
Law of Laplace
pressure generated by surface tension in a sphere
large aveolous = large radiss
low collapsing pressure
small alveolus = small radius
high collapsing pressure
surfactant
phospholipids that line alveoli and reduce surface tension = reduce collapsing pressure of small alveoli
increases lung compliance
w/o surfactant effects
Law of Laplace predicts the small alveolus will collapse (atelectasis)
decreases lung compliance
airflow is proportional to
pressure difference
air flow is inversely proportional to
resistance of the airways
Poiseuille’s Law on resistance and radius of airflow
if radius decreases, the resistances increases (16-fold)
when resistances increases, airflow is decreased
medium sized bronchioles
site of the highest airway resistance
bronchiole smooth muscle is innervated by ____ in parasympathetic and sympathetic
parasympathetic cholinergic nerve fibers
sympathetic adrenergic nerve fibers
Autonomic effects on airway resistance
- Parasympathetic
- Sympathetic
- Lung Volume
- Viscosity of inspired air
parasympathetic stimulation effect on airway resistance
constriction
decreases airway diameter
increase resistance
sympathetic stimulation effect on airway resistance
vasodilation via Beta-2
increases airway
decreases resistance
(epinephrine and albuterol)
lung volume effect on airway resistance
changes in lung volume alter airway resistance b/c the surrounding lung tissue exerts radial traction on airways
High lung volume effect on airway resistance
greater traction
decrease airway resistance
people with asthma breathe at higher lung volumes
low lung volume effect on airway resistance
less traction
increases airway resistance
viscosity of inspired air effect on airway resistance
increase in gas viscosity = increase in resistance
decrease in viscosity = decrease in resistance
