The Fundamentals of Body Buffers and Gases Flashcards
What is the goal of the cellular metabolism
to get oxygen in and acids out
(blank) of carbon dioxide (volatile acid) per day excreted by lung
12 moles
(blank) metabolic acid (non-volatile acid) per day excreted by kidney
0.1 moles
The rate of acid production equals the rate of acid (blank) which results in homeostasis of blood content.
excretion
How is the pH of the blood measured?
extracellularly
If you have balanced ECF pH what else do you have?
balanced interstitial pH and balanced ICF pH
What is a healthy pH? what is a healthy H concentration?
7.35 -7.45
45-35
At what pH can life not be sustained?
below 6.8 and after 7.8
Is HCO3, pH and PaCO2 calculated or measured
HCO3 is calculated
pH and PaCO2 is measured
acid production originated (blank)
intracellularly
Which is more acidic, ICF or ECF?
ICF
Concentrations of buffers in the ICF are (blank) than ECF (~3X)
higher
Cells can (blank) acids and buffers across their membranes to maintain a pH distinct from ECF
actively transport
most body acids are essentally fully ionized at what pH
7.4
what is the standard H concentration to use for equations?
40 nM
At pH 7.4 metabolic intermediates in the charged form are effectively (blank) within the cell
trapped
What is the isohydric principle?
An alteration in pH effects relative concentrations of every conjugate acid and base of all the weak electrolytes.
If the concentration of hydrogen ions is less than the Ka then most of the metabolite will be in its (blank) formed
ionized
buffers can be compared by (blank)
buffer capacity
High capacity buffers are higher in (blank) and their pka’s are closer to the (blank)
concentration
working pH
What is the purpose of a buffer?
pH homeostasis
What is the definition of a buffer?
weak acid-base pai
What do buffers do?
lessen (mitigate) pH changes due to addition of strong acids or bases
What are the main buffers in the ECF?
- hemoglobin (non volatile)
- plasma proteins (non volatile)
- phosphates(non volatile)
- bicarb buffer (volatile)
Why is the bicarb buffer volatile?
cuz CO2 gas is involved
What has the highest buffering capacity?
hemoglobin
Where do you find hemoglobin?
intracellular (in RBC)
RBC membranes are permeable to (blank).
protons
What has an important and rapid impact on the ECF pH?
hemoglobin
Is hemoglobin considered an intracellular or extracellular buffer?
extracellular
Hb has a lot of (blank) at a pka of (blank)
histidine side chains; 6.5
Proteins act as (blank) and are in high concentration in the blod
buffers
(blank) is the most plentiful plasma protein.
albumin
(blank) is an important buffer in the renal tubular filtrate
Phosphate
the functional ionization in the blood has a pKa of what?
6.8
What do all buffers have in common?
weak acid dissociates to conjugate base and a proton
Which kind of buffers mitigate pH changes due to changes in volatile acid (CO2)?
non-volatile buffers (i.e bicarb cannot do this)
Can buffers, buffer endogenous acids?
yes
What is the main source of CO2?
aerobic respiration in mitochondria releases CO2 via the Kreb’s cycle
What is the most powerful buffer of ECF?
bicarbonate buffer (has high buffering capacity but does not buffer CO2)
How many reactions take place within the bicarbonate buffer system?
2 (dissolves CO2, doesnt buffer it)
Pressures of all gases in air add up to the (blank)
barometric pressure
What is the partial pressure of air in reno?
680 mmHg
partial pressure depends upon (blank)
altitude
Pressure units are (blank) units
concentration
What is the ideal gas law equation?
PV=nRT (gives you absolute concentration)
(blank) law states that in a mixture of gases, the pressure exerted by any one gas is proportional to the fraction of the total number of molecules accounted for by that gas.
Dalton’s law (partial pressure)
(blank) is the pressure that the gas would have if it alone occupied the volume.
partial pressure
In a gas, the relative concentration is simply the (blank)
partial pressure
What is the standard Pa at sea level?
760 mm Hg
(blank) is so low that it is clinically considered zero.
PCO2
What is the PO2 in reno? normally?
143, 159
(blank) is the partial pressure of the gas above the liquid.
Pgas
The (blank) of a gas dissolved in a liquid is the partial pressure of that gas which would be genereated in a gas phase in equilibrium with the liquid.
partial pressure
WHy dont you see CO2 bubbles in blood or in a sealed soda?
because it is in equilibrium
In an unopened bottle of soda water, the partial pressure of the gas above the liquid is (blank)
the same as in the liquid
Gases always travel (blank) partial pressure gradients between biological compartments
down
Gases may or may not travel (blank) concentration gradients.
down
which is more important in pulmonary medicine, pressure or concentrations?
pressure!!!
(blank) law quantifies how much gas dissolves in a liquid
henrys law (P X Kh=C)
Use (blanks) law to determine how much gas is dissolved in the blood
henry’s
Henrys constant (Kh) is also called thes olutbility coeffecient and is different for every (blank) an is (blank) dependent.
gas, temperature
What is the standard PCO2?
0.23 mm Hg
What is the standard PaCO2?
35-45 mmHg ~40 mm Hg
(blank) percent of O2 is consumed by the body?
4%
Henry’s constant gives you the (blank) at equilibrium
concentration
If you hold the PaCO2 constant, you will be able to maintain what?
Steady-state
What is the equilbrium dissociation/ henderson eqn?
K acid (dissociation constant)= (hydrogen ions X bicarbonate)/(CO2)
With the bicarb buffer; when HCO3/CO2 equals 1 then Kacid is equal to (blank)
Hydrogen ion concentration
What is the normal Hydrogen ion concentration? What is the normal HCO3-? What is the normal PaCO2?
40 nM
24 nM
40 nM
When using the henderson equation and you get the concentration of the Hydrogen ions, what do you have to do next to determine the pH off of that concentration?
you must remember that the Hydrogen ion concentration is in nanomolars so times that concentration by 10 ^-9 and take th e neftaive log of that number
When the equilibrium concentrations of PaCO2 and HCO3- are known, you can calculate the (blank)
[H+].
Clinically significant deviations from the normal pH correspond to a (blank)-fold changes in hydrogen ion concentrations
2
The solubility coefficient of CO2, in water at 37 C is (blank).
.03 mM/mm Hg
Normal (hco3-/co2) ratio is (blank)
20
If you have hyperventilation what happens to your henderson’s equation?
your Co2 will go down which makes log term go up and pH goes up
If you have hypoventilation, what happens to your henderson’s equation?
ratio goes down,your log term goes down and your pH will go down
How is a buffer with a pKa of 6.1 physiologically important in the maintenance of the normal plasma pH of 7.4?
total concentration of buffer is high and the system is a cheater (gets rid of acid and adds base when you are not looking)
(blank) is open to the atmosphere due to breathing
bicarbonate system
(blank) do act as buffers in response to changes in CO2
Non-volatile buffers
When you are hypoventilating it shifts the equation to the right, what does hemoglobin do now?
hemoglobing sucks up the h+ and acts as a buffer and increases the pH
shift in equilibrium (blank) buffering.
does not equal
Which buffer system is used in metabolic acid production (MAP) and gastrointestinal acid production (GAP)?
Bicarbonate system (volatile)
What are the 2 main processes that acidify the body?
metabolism produces CO2 and endogenous acid production
When metabolism produces CO2 does it produce or consume bicarbonate?
it produces
What is considered all other acidifying processes other than CO2 production?
EAP
(blank) is all Strong acids (from body perspective) MAP and GAP and consumes bicarbonate.
endogenous acid production (EAP)
carbs and lipids have a (blank) effect
net acidifying
(blank) have a net acidifying effect and is the major source of metabolic acid production. Higher % on average of cationic and sulfur-containing amino acids. Amino acid back bone has no effect.
proteins
Organic anions found in fruits and vegetables (potassium salts of acids) have a net (blank) effect
alkanizing
Organic acids are (blank) from the body’s persepctive
strong acids
different (blank) produce different amounts of metabolic acids
diets
Non-industrialized diets (lots of fruits and veggies) results in lower rates of (blank)
metabolic acid production
Industrialized diets (high in meat and eggs, low in fruits and veggies) results in higher rates of (blank)
metabolic acid production
Often hospitalized patients have (blank) acid production
high metabolic
You have a big production of metabolic (non volatile) acid but an even bigger production of (blank) (volatile).
CO2
What is this:
- Acid secreted by the gut into the blood
- Consumes bicarbonate
- Bicarbonate system serves as the buffer for this type of acid load
Gastrointestinal acid production (GAP)
Although the gut secretes both acids and bases into the blood, on average more acid is secreted than base, so there is a net (blank) effect.
acidifying
(blank) can separate HCO3- from H+
Where the H+ go depends upon where in the gut
Gut cells
On balance the gut secretes slightly more (blank) into the blood than HCO3-.These H+ must be buffered by plasma bicarbonate buffering system, thus consuming HCO3-. Therefore the (blank) is buffering this type of acid production
H+
bicarbonate buffer system
EAP is made up of what?
2/3 MAP and 1/3 GAP
i.e. EAP=MAP + GAP
If lungs and kidney function are normal, body can maintain system pH because…..
Using the bicarbonate system and blowing off CO2
Adding bicarbonate back to the blood from the kidneys
What does vomiting cause?
alkalosis
What does diarrhea cause?
acidosis
(blank) puts acid into the blood.
Therefore HCO3 is consume and slight increase in acidity, (blank) allows these levels to return to normal while consuming HCO3 (so they start to deplete). (blank) then adds more HCO3 to blood. THese levels are topped off so system homestasis is achieved.
EAP
alveolar ventilation
Kidney
(blank) eats away at body bicarbonate
EAP
Whose job is it to replace the bicarbonate?
the kidney
What is this:
bicarbonate passes through the glomeruli into the tubular fluid in the nephron.
bicarbonate filtration
What is this:
filtered bicarbonate is actively returned to the blood to make sure that plasma HCO3 does not fall.
bicarbonate reabsorption
What is this:
new bicarbonate is made to replace that used to buffer endogenous acids. (ammonium excretion, titratable acid excretion)
bicarbonate regeneration (acid excretion)
Which of the following has the highest PCO2 in the normal human?
inspired air, expired air, alveolar air, venous blood, arterial blood
venous blood
Which of the following has the lowest PCO2 in the normal human?
inspired air, expired air, alveolar air, venous blood, arterial blood
inspired air
Which is the buffer system with the highest capacity to mitigate pH changes in the blood due to endogenous acid production?
bicarbonate system (cuz open system and high concentration)
What is the fraction of O2 in air at any altitude?
.21