PHYSIOLOGY Flashcards
What are the muscles of inspiration?
diphragm, external intercostals
what are the muscles of inspiration?
normally passive, but can also include abdominal muscles (compress abd. cavity) and internal intercostals
define compliance
changes in lung volume for a change in lung pressure
what is elastance?
the greater the amount of elastic tissue, the greater the tendency to snap back with elastic recoil force, and lower the compliance
what is hysteresis?
when there is a difference in the slopes of inspiration and expiration on a pressure-volume loop. (explains why there is a difference in compliance for inspir. vs. expir.)
how do surfactants work
they reduce the surface tension by reducing the collapsing pressure of an alveoli for a given radius (keeps small alveoli open)
-also increases lung compliance
what is atelectasis
collapse of alveoli
what is the most important constituent of surfactant?
DPPC (dipalmitoyl phosphatidylcholine)
why is there constantly a negative intrapleural pressure?
the lung wants to collapse and the chest wall is trying to expand
what is one test you can do to determine the difference between obstructive and restrictive disease?
peak flow, the peak flow for obstructive diseases is reduced (problem in getting air out), and the peak flow for restrictive diseases should be normal flow but with less volume
what is interdependence
Individual alveoli are prevented from collapsing by the structure of other alveoli holding them open
what 2 things determine lung compliance?
- tissue properties
2. surface forces
what is the name of the organelles in type 2 pneumonocytes that store surfactant?
lamellar bodies
what is the respiratory quotient and what is the normal value?
production of CO2/O2 consumed
normally 0.8
Dalton’s law
in a mixture of gases the pressure exerted by each gas in independent of the pressure exerted by the other gases
henry’s law
relates the concentration of gas in solution to partial pressure (amount dissolved= partial pressure x solubility)
fick’s law
volume flux = SA x (1/thickness) x diffusion constant x concentration difference
If CO2 production is constant then PACO2 is determined by _______________
alveolar ventilation
define hypoxemia
lower than normal PO2
define A-a gradient
difference b/w PAO2 and PaO2, measure of whether O2 has equilibrated b/w alveolar gas and pulmonary capillary blood
define hypoxia
decrease O2 delivery to or utilization by the tissues
define hypercapnia
higher than normal arterial PCO2 (most often due to low alveolar ventilation
why does the Oxygen-HGB dissociation curve have a sigmoid shape?
because of the positive cooperativity
what is the P50
the pressure of oxygen at which HGB is 50% saturated
what 4 things cause a right shift for hemoglobin?
decrease pH
increase in PCO2
increase in temperature
increase 2,3-BPG
what 5 things can cause a left shift of HGB?
increase pH decreased CO2 decreased temperature decreased 2,3-BPG HbF
Bohr effect
explains how increase in CO2 and decrease pH cause right shift on Oxygen dissociation curve
what is Hamburger’s phenomenon?
when bicarbonate diffuses into plasma, leaves a decrease in net negative charge compensated by Cl- movement into cell causing the cell to swell
what is the name of the protein that drives the chloride shift?
band 3 protein
what has a bigger role in CO2 excretion the lungs or the kidneys, and why?
the lungs, they excrete 10,000 mEq/day compared to kidney 100 mEq/day
Lung arteries and arterioles constrict in response to what?
- hypoxia
2. hypercapnia and acidosis
