Lecture 19 Flashcards
Define Acid and Base
Strong acids: Dissociate completely
Weak: do not dissociate completely
Dissociate into H+ ions and a conjugate base
ACID: Compounds that donate an H+
Compounds that release H+ ions
BASE: Compounds that accept the H+
Volatile vs. Nonvolatile acids. Give examples
Volatile acid: Excreted from the lungs: CO2
Non-Volatile acid (fixed acid): Excreted from the kidney: Sulfuric Acid, Phosphoric Acid , ketoacids, lactic acid, salicylic acid.
Define pH and know the normal pH range of venous and arterial blood
pH is the -log [H+],
Arterial blood: pH: 7.37-7.44
Venous Blood pH: 7.35-7.45
Define Equilibrium constant for the dissociation reaction and explain what pKa is.
Ka is the equilibrium constant for the dissociation reaction.
pH=pKa + log ([A-]/[HA])
Major systems in the body that regulate pH
Chemical acid base buffer systems of the body fluids, respiratory center, and kidneys
Buffer
A buffer is a substance that can reversibly bind H+. It consists of a weak acid
HA H+ + A-
Important buffer systems in the body
Bicarbonate Weak acid: Carbonic acid and carbonate salt
Phosphate
Proteins
which buffer system is most important EC system
BICARBONATE BUFFER SYSTEM
How does the bicarbonate buffer system work when a strong acid or a strong base is added.
Increased levels of bicarb can be excreted via kidneys, the net result is a tendency for the carbon dioxide levels in the blood to decrease. This will lead to a decrease in respiration rate.
Organ that primarily regulates the bicarbonate buffer system.
Bicarbonate concentration is regulated by kidneys. PCO2 is controlled by rate of respiration. MOST IMPORTANT EXTRACELLULAR BUFFER SYSTEM
metabolic acid-base disorders vs. respiratory acid base disorders.
Metabolic acidosis: Lower bicarbonate
Metabolic alkalosis: higher carbonate.
Based on changes in the extracellular concentration
Respiratory acid base disorders are in regards to pCO2. Acidosis: increase in Carbon dioxide in blood. Rest. Alkalosis: decrease in CO2
how does operating pH point for the bicarb buffer system compare to its pKa?
pH 6.1 occurs when concentrations of both carbonate and carbon dioxide are equal. Therefore pH=pKa of the buffer system.
what is the phosphate buffer system and why is it more important as a buffer in the kidney tubular fluids?
Phosphate buffer system plays a major role in RENAL TUBULAR FLUID Buffering and intracellular fluids.
WHY? kidney tubular fluids become concentrated in tubules. Lower pH of the tubular fluid brings the operating range of the the buffer closer to the pK of the buffer system.
how do we remove non volatile acids?
renal excretion
What must happen before filtered bicarb is resorbed?
must react with secreted hydrogen ion to form carbonic acid before it can be reabsorbed. 4320 mEq of hydrogen ion must be secreted each day just to reabsorb 4320 mEq of filtered bicarb.
