Unit 2, L19 Acid Base 1 Flashcards
Too much acid is what
Acidosis
Too little acid is what
Alkalosis
ECF pH is what range, normally, and what concentration of H+
7.35-7.45, and 40 nM
Plasma levels depend on
Metabolism of ingested food
Secretions of GI
De novo synthesis of acid and base from metabolism of stored fat and glycogen
Changes in production of CO2
When we have O2 and insulin, what happens to the fats and carbohydrates?
Turn into H2O and CO2 and get sent to the lungs
In anaerobic conditions or if we deplete insulin, or if we ingest lots of proteins, or have fecal HCO3 loss, what will all of this produce?
HA in its acid form + NaHCO3
HA + NaHCO3 goes to what and where do the byproducts go
HA + NaHCO3 turns to NaA + H2O + CO2
H2O and CO2 go to the lungs
NaA turns into NEAP, which goes to the kidneys
Two key processes of acid base balance
1) Excretion of acid-base equivalents to their inputs
2) Regulation of weak acids to conjugate bases in buffer systems
The lungs will excrete what
CO2, a volatile acid
Kidneys will excrete what
They will excrete acid, RNAE (renal net acid excretion) equal to NEAP (net endogenous acid production), which reflects dietary intake, cellular metabolism, and loss of acid and alkali from the body
pH of blood is normally
7.4
Intracellular pH is approximately
7.2
The normal pH for arterial plasma ranges from
7.35-7.45
What is the range for acidemia
If the pH < 7.35, so concentration of H+ is increasing
What is the range for alkalemia
pH > 7.45, so H concentration is decreasing
Why is CO2 a volatile acid
It has the potential to form H+ upon hydration, but it itself is not an acid
CO2 to HCO3 equation
CO2 + H2O H2CO3 H+ + HCO3-
This is done by carbonic anhydrase
The cycle of CO2 in the body
CO2 leaves the cells, enter the venous supply in RBCs, where it is converted to H+ and HCO3-. It is carried to the lungs where it is converted back to CO2 and expired
Catabolism of proteins and phospholipids produces ______
50 mM/day of fixed acid
Sulfuric acids
Produced from proteins with the sulfure-containing amino acids when metabolized
Phosphoric acid is produced from
Phospholipids
A buffer is what
A mixture of a weak acid and its conjugate base or a weak base and its conjugate acid
A buffered solution resists a change in pH
Bronsted-Lowry equilibrium equation
HA + B A- + HB+
What is pKa
When the rates of the forward and reverse reactions are equal, there is chemical equilibrium, so there is no net change in concentration of HA or A=
What is the Henderson-Hasselbalch equation
pH = pKa + log ([A-]/[HA])
HA is CO2, pKa is of the buffer, A- is what is in the kidneys while HA is what is in the lungs
When pH = pKa, what happens
The world explodes
Nah, there are equal concentrations of HA and A-
A buffer is most effective when
Its pKa = environmental pH
Strong acids have what type of pKa and K
High K and low pKa
Weak acids, like H2CO3, have what kind of pKa and K
Low K and high pKa
What are the two key buffer systems in the ECF
Bicarbonate (pKa = 6.1)
Phosphate (pKa = 6.8)
What is the most important extracellular buffer
HCO3-/CO2
What must you do to CO2 before using it to calculate pH
PCO2 must be converted to CO2 concentration by multiplying by the solubility of CO2 in blood, which is 0.03 mmol/L per mmHg
For Bicarb, what is the pKa, values of A- in the kidneys, and values of HA in the lungs (PCO2)
pKa is 6.1
HCO3 in the kidneys is 24 mM
PCO2 in the lungs is 40 mmHg
Why is bicarb a better buffer than phosphate
2 reasons
1) HCO3- is much higher concentration than phosphate
2) The acid from of the bicarb buffer is volatile CO2 and can be expired by the lugns
The most significant intracellular buffer is what
Hemoglobin
