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FRC (functional residual capacity)
RV + ERV, vol in lungs after norm exp, relaxed state, Ptp = Pcwr, where total pulmonary vasc resist is lowest
obstructive lung disease
clinical: char by dec FEV1,dec FEV1:FVC (<0.8), dec FEF25-75, inc compliance, ex: COPD, bronchitis, emphysema, asthma
restrictive lung disease
clinical: char by dec FEV1, norm FEV1:FVC (0.8), dec FVC, norm FEF25-75, dec compliance ex: fibrosis
phospholipids secreted by Type II pneumocytes, inc SA -> dec [suractant] -> inc ST -> dec C
method to calc FRC, able to account for obstructive lung diseases - 1) calc Vt w/ Boyle's law, 2) FRC = P4*Vt/deltaP
alveolar gas equation
PAO2 = PIO2 - (PACO2/R) = O2 insp - alveolar (meas via arterial) CO2 / R (norm 0.8 for norm diet)
ex: bronchial circ, congenital heart defects, when some deox bl joins the ox bl at the PV -> LA, gen non-path
ex: pneumothorax, V/Q mismatch, when large areas of lung are not ventilated -> deox bl in PV -> LA
takes 2-5% of CO to supply conducting airways, returns to PV as deox bl => anatomical shunt
O2 transfer time
time RBC spends to cross length of pulm capp ~0.75s (0.25s to ox, 0.5s capp reserve t)
the small rise in [CO2] after being picked up by the tissues since not that much is expirated as you may think
part of lung char by high resting vol, small Pip gradient (small vol inc w/insp), low ventilation
part of lung char by small resting vol, large Pip gradient (large vol inc w/insp), high ventilation
loc on ventral medulla, sense PCO2 (within 3mmHg of set point) via H+ in CSF -> strong resp drive
include aortic arch (X) + carotid body (IX) Rs that sense change in PCO2, PO2, pH
carotid body chemoreceptors
very strong peripheral chemoreceptors, IX afferents, high metab activity (4x brain), bl supply 40x of brain, can be fine-tuned by ANS activity in order to inc medulla stim to inc resp drive
clusters w/ supporting sustentacular glia that are the sensory cells of the carotid and aortic bodies, responds to dec PO2 by closing O2sensitive K_ chans -> open VG Ca2+ chans -> send NTs to medulla (via IX for carotid or X for aortic)
VRG (ventral respiratory group)
part of medulla active mainly for forced expiration (and some inspiration)
aka juxtapulmonary cappillary or C-fiber endings, fire in response to lung injury, onver infl, edema, embolism (alveolar C fibers) or inflamm (bronchial C fibers) -> rapid shallow breathing, bronchoconstrict
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