Create an account
potential space w/ little fluid (~15mL in adults)
intrapleural pressure is subatmospheric
normally an active process
- diaphragm (major muscle), innervated by phrenic nerve, spinal roots C3,4 & 5
- external intercostals - ↑ intrathoracic volume
-accessory muscles (seen in Dz): sternocleidomastoid & scalenes
usually a passive process
muscles involved (note: only in forced expiration)
- rectus abdominus
- internal intercostals
↓ complaince (stretchability) causes?
lung Dz's that cause scarring & fibrosis
ex: Pulmonary fibrosis
obstructive lung Dz
↑ compliance lung Dz - ex: emphysema
- tissue loss (↓ recoil forces) causes easily compressed airways
- produces ↓ air flow rates & ↑ airway resistance
- pts work hard to overcome airway resistance on expiration
restrictive lung Dz
↓ compliance lung dz - ex: pulmonary fibrosis
- fibrosis causes ↑ elastic recoil
- ↑ radial traction→ airway dilation
- produces → ↑ air flow rates & ↓ airway resistance
- pts work hard to overcome ↑ elastic recoil during inspiration
what is the cause if a pt has to work hard to overcome airway resistance on expiration?
obstructive lung Dz
what is the cause if a pt has to work hard to overcome increase elastic recoil during inspiration?
restrictive lung Dz
- synthesized by type II alveolar cells & coats lining of alveolous
- ↓ intermolecular forces between water molecules
- usually present by 35 weeks gestation
what is airway resistance determined by?
- Major factor: airway diameter
-- note: if radius ↓ then resistance to airflow ↑
- rate of gas flow
major site of airway resistance = medium sized bronchi
Adrenergic stimulation causes what in airways?
name 2 β2-selective adrenergic agents
- β2-receptor stumlation = smooth muscle relaxation
β2-selective adrenergic agents:
- albuterol (short acting)
- salmetrol (long acting)
beta blockers causes what in airways? who is this bad for?
bad for asthmatics, people w/ obstructive Dz
cholinergic stimulation in airways causes? what agent would you administer?
bronchoconstriction & ↑ mucus production
administer anticholinergic agents for bronchodilation
nonadrenergic, noncholinergic activity for control of airway resistance
neuropeptides that contol airway smooth muscle
eg. vasoactive intestinal peptide (VIP), nitric oxide (NO)
note: no clinically available therapeutic agents for these substances yet
what inflammatory mediator controls airway resistance & what are its effects? what agent would you administer?
Leukotrienes (LT) - potent bronchoconstrictor
LT inhibitors (modifiers) for bronchodilation
LT inhibitors - Zafirlukast, Montelukast
forced expiratory volume in 1 sec (FEV1)
screening test for airway Dz
indicated volume of FVC expired in 1st second - shows flow resistance properties of airways
what does pulse oximetry (pulse-ox) measure? what is is dependent on?
- using a red light emitting diode, pulse-ox indirectly measures O2 saturation (SaO2)
- measurement dependent upon adequate tissue perfusion
explain oxygen transport in the lungs
- O2 diffuses across alveolus
- dissolves in plasma of pulmmonary capillaries
- diffuses into RBC & binds w/ Fe w/in Hb molecule
- deoxyhemoglobin → oxyhemoglobin (normal Hb=12-15 g/dL blood)
explain oxygen transport in the tissues
- PO2 is low secondary to metabolism
- O2 dissociates from Hb
- moves across RBC membrane
- dissolves in plasma
- diffuses across capillary wall
- finally enters interstitial tissue
- Hb + carbon monoxide (CO)
- gives skin a cherry color
- binding affinity of CO: 200x > O2
- binding is IRREVERSIBLE → TOXIC
Fe+2 → Fe+3 state → unable to bind O2
- gives skin "bluish" cyanotic color
- caused by drugs/foods (nitrates, fava beans) esp in pts w/ G6PD deficiency
explain carbon dioxide transport w/in the RBC
- 90% of CO2 enters RBC & is returned to lungs
- CO2 + H2O + carbonic anhydrase → H2CO3 → HCO3- + H+
- HCO3 - then diffuses out of RBC into plasma
explain carbon dioxide transport in the lungs
HCO3- in blood enters RBC + H+ → H2CO3 → H2O + CO2
CO2 exists cell into alveolous
Please allow access to your computer’s microphone to use Voice Recording.
Having trouble? Click here for help.
We can’t access your microphone!
Click the icon above to update your browser permissions and try again
Reload the page to try again!Reload
Press Cmd-0 to reset your zoom
Press Ctrl-0 to reset your zoom
It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.
Please upgrade Flash or install Chrome
to use Voice Recording.
For more help, see our troubleshooting page.
Your microphone is muted
For help fixing this issue, see this FAQ.
Star this term
You can study starred terms together