Test Bank Guyton and Hall Textbook of Medical Physiology
14th Edition Hall | 9780323597128 | All Chapters with
Answers and Rationals
Why is it important to regulate H+ concentration in the body? - ANSWER: activity of almost every
enzyme is dependent on H+ concentration
molecules which release H+ ions in solutions are - ANSWER: acids
molecules which accept a H+ ion in a solution are - ANSWER: bases
define alkali - ANSWER: molecule formed by combination of one or more alkaline metals (Na, K, Li,
etc.)
whats the difference between strong and weak acids - ANSWER: strong acids rapidly dissociate and
released large amounts of H+ while weak acids are less likely to do that
why do we use logarithm scale when expressing H+ concentration? - ANSWER: bcuz H conc is really
low
what is normal pH of arterial blood? - ANSWER: 7.4
What are the three primary systems which regulate H+ concentration in body fluids? - ANSWER: 1)
chemical acid-base buffer systems of the body fluids (1st line resisting change)
2) respiratory center regulates removal of CO2 (2nd line)
3) kidneys excrete acid/base into urine (3rd line, slow to respond)
describe the bicarbonate buffer system equation - ANSWER: CO2 +H2O <- -> H2CO3 <- -> H + HCO3
carbonic anhydrase is the enzyme in charge
adding any of one molecule will shift reaction to the other way
metabolic acidosis/alkalosis is primarily caused by what? - ANSWER: decrease/increase in HCO3
respiratory acidosis/alkalosis is primarily caused by what? - ANSWER: increase/decrease in CO2
when the acid and base components of a buffer are equal to each other, what is the pH? - ANSWER:
pKa
what pH is a buffer most effective? - ANSWER: At the buffer's pKa
stops working +/- 1 from pKa
whats the most important extracellular buffer we have? - ANSWER: bicarb
what are two reasons why bicarb buffer system is not perfect. How does it still remain the most
effective tool? - ANSWER: 1) extracellular pH is 7.4, pKa of bicarb buffer system is 6.1; meaning the
system operates on a low portion of the buffering curve
2) concentrations of CO2 and HCO3 is not particularly high
, Our bodies regulate HCO3 and CO2 really well with kidneys and lungs so we have precise control over
rates of addition and removal of HCO3 and CO2
whats the phosphate buffer equation (both acid and base) - ANSWER: HCl + 2NaHPO4 --> Na2HPO4 +
NaCl
NaOH + NA2HPO4 --> 2NaHPO4 + H2O
what is the phosphate buffer pKa and why is that significant? - ANSWER: pKa is 6.8 , much closer to
7.4 than bicarb
limitation is low concentration in ECF
more important in the tubular fluids in kidney and ICF
Explain the phosphate buffer in the kidneys - ANSWER: 1) phosphate becomes greatly concentrated in
tubules, increasing buffering power of phosphate system
2) tubular fluid usually has lower pH than ECF, bringing operating range closer to pKa 6.8 of the
system
explain the phosphate buffer system in the ICF - ANSWER: concentration of phosphate is much higher
ICF than ECF
ICF has lower pH than ECF, closer to phosphates pKa
besides phosphate buffers, what else is important in ICF buffering - ANSWER: proteins
pKa is similar to ICF pH
what buffers in RBCs? - ANSWER: Hb
describe the isohydric principle - ANSWER: how all the buffer systems work together to soak up the
H+; a balance of all buffer systems
the overlapping buffer systems can buffer one another by shifting H+ ions between themselves
alveolar ventilation relates to pH how? - ANSWER: increased ventilation = increased pH (decreased
CO2)
how significant are the changes to pH if we change alveolar ventilation? - ANSWER: increasing
alveolar ventilation to double of normal means pH increases to 7.63
decreasing alveolar ventilation to 1/4 normal ventilation means pH decreases to 6.95
large effects
what automatically happens to alveolar ventilation when blood pH decreases? - ANSWER: alveolar
ventilation increases 4-5 times
does acidosis or alkalosis have a greater effect on ventilation rate? why? - ANSWER: acidosis
because when alkalosis causes a decrease in ventilation rate, the decrease in oxygen levels causes an
increase in ventilation, so it is not as effective for alkalosis
what is the buffering power of respiratory system? - ANSWER: rapid and powerful
14th Edition Hall | 9780323597128 | All Chapters with
Answers and Rationals
Why is it important to regulate H+ concentration in the body? - ANSWER: activity of almost every
enzyme is dependent on H+ concentration
molecules which release H+ ions in solutions are - ANSWER: acids
molecules which accept a H+ ion in a solution are - ANSWER: bases
define alkali - ANSWER: molecule formed by combination of one or more alkaline metals (Na, K, Li,
etc.)
whats the difference between strong and weak acids - ANSWER: strong acids rapidly dissociate and
released large amounts of H+ while weak acids are less likely to do that
why do we use logarithm scale when expressing H+ concentration? - ANSWER: bcuz H conc is really
low
what is normal pH of arterial blood? - ANSWER: 7.4
What are the three primary systems which regulate H+ concentration in body fluids? - ANSWER: 1)
chemical acid-base buffer systems of the body fluids (1st line resisting change)
2) respiratory center regulates removal of CO2 (2nd line)
3) kidneys excrete acid/base into urine (3rd line, slow to respond)
describe the bicarbonate buffer system equation - ANSWER: CO2 +H2O <- -> H2CO3 <- -> H + HCO3
carbonic anhydrase is the enzyme in charge
adding any of one molecule will shift reaction to the other way
metabolic acidosis/alkalosis is primarily caused by what? - ANSWER: decrease/increase in HCO3
respiratory acidosis/alkalosis is primarily caused by what? - ANSWER: increase/decrease in CO2
when the acid and base components of a buffer are equal to each other, what is the pH? - ANSWER:
pKa
what pH is a buffer most effective? - ANSWER: At the buffer's pKa
stops working +/- 1 from pKa
whats the most important extracellular buffer we have? - ANSWER: bicarb
what are two reasons why bicarb buffer system is not perfect. How does it still remain the most
effective tool? - ANSWER: 1) extracellular pH is 7.4, pKa of bicarb buffer system is 6.1; meaning the
system operates on a low portion of the buffering curve
2) concentrations of CO2 and HCO3 is not particularly high
, Our bodies regulate HCO3 and CO2 really well with kidneys and lungs so we have precise control over
rates of addition and removal of HCO3 and CO2
whats the phosphate buffer equation (both acid and base) - ANSWER: HCl + 2NaHPO4 --> Na2HPO4 +
NaCl
NaOH + NA2HPO4 --> 2NaHPO4 + H2O
what is the phosphate buffer pKa and why is that significant? - ANSWER: pKa is 6.8 , much closer to
7.4 than bicarb
limitation is low concentration in ECF
more important in the tubular fluids in kidney and ICF
Explain the phosphate buffer in the kidneys - ANSWER: 1) phosphate becomes greatly concentrated in
tubules, increasing buffering power of phosphate system
2) tubular fluid usually has lower pH than ECF, bringing operating range closer to pKa 6.8 of the
system
explain the phosphate buffer system in the ICF - ANSWER: concentration of phosphate is much higher
ICF than ECF
ICF has lower pH than ECF, closer to phosphates pKa
besides phosphate buffers, what else is important in ICF buffering - ANSWER: proteins
pKa is similar to ICF pH
what buffers in RBCs? - ANSWER: Hb
describe the isohydric principle - ANSWER: how all the buffer systems work together to soak up the
H+; a balance of all buffer systems
the overlapping buffer systems can buffer one another by shifting H+ ions between themselves
alveolar ventilation relates to pH how? - ANSWER: increased ventilation = increased pH (decreased
CO2)
how significant are the changes to pH if we change alveolar ventilation? - ANSWER: increasing
alveolar ventilation to double of normal means pH increases to 7.63
decreasing alveolar ventilation to 1/4 normal ventilation means pH decreases to 6.95
large effects
what automatically happens to alveolar ventilation when blood pH decreases? - ANSWER: alveolar
ventilation increases 4-5 times
does acidosis or alkalosis have a greater effect on ventilation rate? why? - ANSWER: acidosis
because when alkalosis causes a decrease in ventilation rate, the decrease in oxygen levels causes an
increase in ventilation, so it is not as effective for alkalosis
what is the buffering power of respiratory system? - ANSWER: rapid and powerful
