Acid-base Regulation Flashcards
What is an acid?
A substance that can release or donate an H+
What is a base?
A substance that can combine with or accept an H+
What is the Ka?
Acid dissociation constant
Equilibrium constant/ionization constant
The higher the dissociation constant….
The more an acid is ionized and the greater its strength
What are some strong acids?
HCl, H2SO4, H3PO4, HNO3
What are some weak acids?
Acetic acids, lactic acid, H2CO3, NH4+, H2PO4-
pKa is _____ to acid strenth.
Inversely proportional
What are some ways that acid could be produced in the body?
Metabolism -> CO2
Incomplete carbohydrate and fat metabolism -> nonvolatile acid
Protein metabolism > strong acid
The net endogenous acid production (NEAP) is found…
1 mEq H+/kg body weight
Acid production via CO2.
CO2 + H2O H2CO3 H+ + HCO3-
What are the pH regulation mechanism?
Chemical buffering
Respiratory response
Renal response
What is the first line of pH flux defense and what does it do?
Chemical buffering
Minimizes a change in pH
DOES NOT remove acid or base
What is the second line of defense and what does it do?
Respiratory response
Remove CO2
What is the third line of defense and what does it do?
Renal response
Remove excess H+
Add new HCO3-
Slow
What is the main buffer pair?
HCO3-/CO2
Mixture of weak acid and conjugate base or vice verse
What is normal arterial PCO2 and [HCO3-]?
40 mmHg, 24 mmol/L
Henderson-Hasselbalch equation.
pH = 6.1 + log([HCO3-] / 0.03 x PCO2)
What is chloride shift?
HCO3- diffuses out of RBC
RBC membrane is relatively impermeable to H+
Cl- diffuses into the RBC to maintain electrical neutrality
What is the process of forming CO2 in the lungs?
H+ + HCO3- H2CO3 H2O + CO2
What is the enzyme which aid in the formation of H2CO3?
Carbonic anhydrase
What is a titratable acid?
Number of mEq OH- needed to bring the urine pH back to the pH of blood
Presents the amount of H+ that is excreted combine with urinary buffers like phosphate or creatinine
What acid in renal acidifcation is nor titratable?
Ammonia (NH3/NH4+)
If H+ is lost in the urine it is the same as….
Adding more HCO3- to the blood
What is a simple acid-base disturbance?
Single primary cause for the disturbance
Acidosis
Acid addition/ alkali loss
Alkalosis
Alkali addition/ acid loss
Respiratory acidosis with renal compensation is present when PCO2 is ____ and HCO3- is ____.
High, low
Respiratory alkalosis with renal compensation is present when PCO2 is ____ and HCO3- is ____.
Low, high
Metabolic acidosis with respiratory compensation is present when PCO2 is ____ and HCO3- is ____.
Low, low
Metabolic alkalosis with respiratory compensation is present when PCO2 is ____ and HCO3- is ____.
High, high
What could cause metabolic acidosis?
Gastrointestinal loss of bicarb like diarrhea
Diabetic ketoacidosis
What could cause metabolic alkalosis?
Gastric H+ loss such as vomiting
Net gain of HCO3- such as absorbable antacids or eating baking soda
What could cause respiratory acidsosis?
Emphysema
Pulmonary edema
What could cause respiratory alkalosis?
Voluntary hyperventilation
Anxiety
High altitude
What are the three models of to remove acid from the body via the kidneys?
HCO3- reabsoprtion
Titratable acid formation
Ammonia synthesis and excretion
