VPHY 3100 Final

VPHY 3100 Final
bicarbonate buffer system - ANSWERSCarbon dioxide <-> carbonic acid <-> bicarbonate


what enzyme converts CO2 to H2CO3 and vice versa - ANSWERScarbonic anhydrase


CA= carbonic anydrase - ANSWERS-catalyzes reaction both directions
-higher expression in RBCs, gastric mucosa, pancreatic exocrine cells, renal tubules
-essential to understand CO2 transport


CO2 transported in the blood in 3 forms - ANSWERS-dissolved CO2 (10%) accounts for PCO2
-carbaminohemoglobin(20%)
-HCO3- (70%)


carbaminohemoglobin - ANSWERS-unlading of O2-> Hb-> Hb-CO2 forms
-CO2 does not bind heme(iron) in HB, but a amino


carbonic anhydrase located in - ANSWERSRBCs


CO2 readily crosses - ANSWERSplasma membrane


Bicarb (HCO3-) needs to be transported across plasma membranes. antiporter exchanges - ANSWERSchloride
for bicarb


pairing Cl- and HCO3- movement in opposite directions always couples - ANSWERSone moving along a
concentration gradient with one moving against a concentration gradient (secondary active transport)


ions high extracellular levels - ANSWERSNa+, Ca2+, Cl-, HCO3-

,ions high in intracellular fluid - ANSWERSK+, PO3, proteins


At system capillaries - ANSWERSchloride shift into RBS, carbonate leaves into bloodstream


At pulmonary capillaries - ANSWERSreverse chloride shift out of RBS, HCO3- enters RBC and Cl- enters
bloodstream


pH - ANSWERSconcentration of H+ ions in aqueous solution
pH=-log[H+]


Normal blood pH - ANSWERS7.40 (7.35-7.45)


Acidosis - ANSWERSpH< 7.35 increase H+ ions


Alkalosis - ANSWERSpH > 7.45 lower H+ ions


Blood pH is maintained within narrow pH range by - ANSWERSlungs and kidneys


CO2 adjusted by ___ and HCO3- adjusted by___ - ANSWERSlungs, kidneys


2 major classes of acids in body - ANSWERSvolatile and nonvolatile


Volatile can be - ANSWERSconverted to a gas
-CO2 in bicarbonate buffer system can be exhaled


Nonvolatile acids - ANSWERScannot leave the blood
-need to bind to buffer molecules
-buffers in the body includes HCO3-, PO42-, proteins including Hb


hyperventilation - ANSWERSremoves H+ ions, thereby increasing pH

, -can lead to acidosis


hypoventilation - ANSWERSincreases H+ ions, thereby decreasing pH
-causes alkalosis


The H+ in lungs is - ANSWERSform of water associated with CO2


central chemoreceptors - ANSWERS-located in medulla, different from the rhythmicity center
-more sensitivity to blood PCo2 than blood pH


Peripheral chemoreceptors - ANSWERS-carotid and aortic bodies
-directly changes in Po2
-indirectly direct changes in Pco2 through pH
-more sensitive to changes in blood pH than Po2


baroreceptors - ANSWERScartoid sinuses and aortic arch


chemoreceptors - ANSWERScartoid bodies and aortic bodies


integrator of breathing regulation - ANSWERSbrain stem respiratory centers (medulla ablongata and pons)


Effectors of breathing - ANSWERSrespiratory muscles


How do lungs respond to acidosis - ANSWERSincrease PCo2, increase respiratory rate to decrease CO2


How do the lungs respond to alkalosis - ANSWERSlow H+-> low PCO2-> decrease respiratory rate


respiratory acidosis - ANSWERS-caused by hypoventilation
-accumulation of CO2 in the tissues -> increase Pco2 in blood -> decrease pH of blood