pH Flashcards
pH is a measure of the concentration of the _____.
free hydrogen ions in a water-
based solution
A buffer is a substance which, when in solution, is able to _____, so that the _____.
bind or release hydrogen ions;
pH remains nearly constant
The strength of an acid or base refers to its _____: a strong acid, for example, will _____
in water.
ability to ionize; completely
dissociate to give free H+
The strict definition of _____ means a blood pH that is too low, while _____ refers to the
conditions that promote the lowering of blood pH. However, in actual practice, the two
terms are often treated as synonyms.
acidemia; acidosis
The strict definition of _____ means a blood pH that is too high, while _____ refers to the
conditions that promote the increase in blood pH. However, in actual practice, the two
terms are often treated as synonyms.
alkalemia; alkalosis
The normal pH of arterial blood is _____. If the pH drops 0.05 units to reach _____, the
person has _____; if instead it rises 0.05 pH units, the person has _____.
7.40; 7.35; acidemia; alkalemia
The pH of the body’s fluids must be tightly controlled: two major effects of shifts in pH are
changes in _____ and _____.
protein folding; electrolyte
distribution
____ in the blood respond almost instantly to small changes in pH. Their levels can be
altered by two of the body’s systems: the _____ and _____.
Buffers; lungs; kidneys
There are three major chemical buffer systems in the body: the bicarbonate buffer system
in the _____, the phosphate buffer system in the _____ and _____, and the protein buffer
system in the _____
ECF; ICF; urine; ICF
When hydrogen ions are added to a bicarbonate buffer system in the body, they bind to
_____ to form _____
bicarbonate; carbonic acid
When hydrogen ions are removed from a bicarbonate buffer system in the body, _____
releases hydrogen ions which replace those that were removed.
carbonic acid
When hydrogen ions are added to a phosphate buffer system in the body, they bind to
_____ to form _____.
hydrogen phosphate;
dihydrogen phosphate
When hydrogen ions are removed from a phosphate buffer system in the body, _____
releases hydrogen ions which replace those that were removed
dihydrogen phosphate
When hydrogen ions are added to a protein buffer system in the body, they bind to the
side-chains of _____ and _____.
histidine; cysteine
There is an endless supply of carbon dioxide in the body because it is formed during
_____. Most is taken in by _____ and enzymatically converted to _____.
cellular respiration;
erythrocytes; bicarbonate
The reaction relating carbon dioxide and the pH of an aqueous solution is _____.
CO2 + H2O H2CO3
H+ + HCO3-
_____’ refers to a condition in which the level of CO2
in the arterial blood is too high:
‘_____’ refers to when the level is too low
Hypercapnia; hypocapnia
CO2 dissolved in the blood is usually denoted by ‘_____,’ which refers to the pressure of
the gas.
PCO2
H+
can be removed from the blood by adding it to bicarbonate to form carbonic acid, then
splitting the carbonic acid to water and CO2
; this reaction can be accelerated by increasing
_____, which removes the _____ from the blood
breathing rate; CO2
. Alterations in the blood pH due to changes in breathing rate takes _____ .
several minutes
Both hypercapnia and acidemia act on the medullary respiratory center to _____
breathing rate
increase
Both hypocapnia and alkalosis act on the medullary respiratory center to _____ breathing
rate.
decrease
The kidneys have three mechanisms by which they can raise the pH of the blood: they
can deaminate glutamine and secrete H+
bound to the resulting _____, or can produce
_____ and then secrete the resulting H+
directly or by countertransport with sodium
ammonia; carbonic acid
In order for the kidneys to alter blood pH, up to _____ may be required.
several days
In response to hypercapnia, the kidneys use CO2
to produce _____, and then secrete
_____ into the urine and _____ into the blood.
carbonic acid; hydrogen ions;
bicarbonate ions
When a large number of hydrogen ions are secreted into the urine, the
bicarbonate/carbonic acid equilibrium in the urine is shifted toward formation of _____,
which can enter the cells of the PCT or collecting duct and be reused. This prevents the
urine from becoming too acidic.
CO2
Some of the hydrogen ions that are secreted into the urine are buffered by the _____ that
is present there. This prevents the urine from becoming too acidic
hydrogen phosphate
In response to low blood pH, PCT cells in the kidney deaminate glutamine to form _____,
which is quickly protonated to _____ and secreted. This discards a hydrogen ion while
preventing the urine from becoming too acidic
ammonia (NH3); ammonium
ion (NH4+ )
Hydrogen ions are secreted into the urine by use of _____ or ______ countertransport or
by use of a(n) _____.
Na+; K+; H+-ATPase
The secretion of hydrogen ions into urine is inhibited if the urine’s pH is _____.
below 4.5
One of the causes of changes in the blood’s pH is the ingestion or production of complex
acids or bases (such as uric acid, which is produced by catabolism of nucleic acids).
These are disposed of by the _____
kidneys
To lower the pH of the blood, type B cells in the collecting duct of the kidney can catalyze
the formation of carbonic acid: to lower the pH of the blood, however, they secrete the
_____ into the urine, and the _____ into the blood
HCO3- ; H+
Because pH directly influences the _____ equilibria, PCO2
in the blood varies depends on
pH. A very rough estimate of the expected PCO2
is that it will equal _____, in mm Hg. (Be
able to make such an estimate.)
carbonic acid/bicarbonate; the
last two digits of the pH (e.g.,
41 for pH 7.41)
If PCO2
is higher than expected, it indicates that respiration is _____, but it does not tell
you whether this is the cause of a problem, or merely a symptom.
slower than normal
If PCO2
is lower than expected, it indicates that respiration is _____, but it does not tell
you whether this is the cause of a problem, or merely a symptom.
faster than normal
Respiratory acidosis promotes a decrease in the blood’s pH that contributes to acidemia,
and which is directly caused by _____. It causes PCO2
to be _____ than expected.
insufficient exhalation of CO2;
higher
Respiratory alkalosis promotes an increase in the blood’s pH that contributes to alkalemia,
and is directly caused by _____. It causes PCO2
to be _____ than expected
excessive exhalation of CO2;
lower
Metabolic acidosis promotes a decrease in the blood’s pH that contributes to acidemia,
but is caused by the _____ or by the _____ by systems other than the respiratory system
addition of hydrogen ions;
removal of bicarbonate ions
Metabolic alkalosis promotes an increase in the blood’s pH that contributes to alkalemia,
but is caused by the _____ or by the _____ by systems other than the respiratory system
`removal of hydrogen ions (as
by a reaction); addition of
bicarbonate ions
. Metabolic acidosis causes the concentration of bicarbonate to _____ as _____.
drop; bicarbonate reacts with
hydrogen ions
Metabolic alkalosis causes the concentration of bicarbonate to _____ as _____.
rise; lost hydrogen ions are
replaced by hydrogen ions from
carbonic acid
Some medical conditions lead to combinations of _____ and _____ shifts in blood pH:
some poisons, for example, directly change blood pH but also depress breathing.
O
respiratory; metabolic
One common cause of _____ is the production of excessive amounts of ketoacids (often
called ‘ketone bodies’) in uncontrolled diabetes
metabolic acidemia
One common cause of _____ is emphysema, in which the body’s ability to expel carbon
dioxide through the lungs is impaired
respiratory acidemia
The loss of stomach acid due to vomiting, as would occur with an acute stomach illness, is
one possible cause of _____.
metabolic alkalemia
____ is often caused by pain or anxiety, and can be cured simply by having the patient
re-breathe expelled air to slow carbon dioxide losses.
Respiratory alkalemia
Patients suffering from a metabolic acidosis will often breathe _____ in order to _____;
this is called ‘_____.’
quickly; expel more CO2;
respiratory compensation
Patients suffering from a metabolic alkalosis will often breathe _____ in order to _____;
this is called ‘_____.’
slowly; conserve CO2;
respiratory compensation
Patients suffering from a acidosis that is not caused by the kidneys (the kidneys can’t
compensate for their own failure!) will excrete fewer _____ and more _____ in the urine.
This is called ‘_____.’
bicarbonate ions; hydrogen
ions; renal compensation
Patients suffering from alkalosis that is not caused by the kidneys (the kidneys can’t
compensate for their own failure!) will excrete fewer _____ and more _____ in the urine.
This is called ‘_____.’
hydrogen ions; bicarbonate
ions; renal compensation
Aldosterone secretion is _____ in response to acidosis because _____ (thus, conserving
sodium helps to increase _____).
stimulated; Na+ and H+ are
countertransported; H+
secretion
