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34 Cards in this Set

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  • Back
What is a an acid?
A chemical species that dissociates into a proton (H+) and an ionic species.
What is a base?
A chemical species that combines with a proton.
What is the product of an acid-base reaction.
Typically water and a salt.
What is pH a measure of?
The proton concentration in solution and therefore the acidity.
What is a buffer?
In biology, a buffer is typically a weak acid that minorily dissociates but can reform the acidic species when an excess of proton (H+) is introduced.
Are strong acids buffers?
No. A strong acid fully dissociates.
What is the most common buffer found in the body?
Bicarbonate.
What three main buffers are found in the body?
1. Bicarbonate (HCO3 - )
2. Ammonia (NH3)
3. Phosphate (HPO4 - -)
What is the buffered species of bicarbonate?
H2CO3 which can dissociate into H2O and CO2. CO2 is then expelled through respiration.
What is the buffered species of ammonia?
NH4+ and is found in urine.
What is the buffered species of phosphate?
H2PO4 -
Can proteins be used as buffers?
Yes because they are often negatively charged and will accept the positive proton.
Where is the main source of acid in the body?
From metabolic sources such as lactic acid, carbonic acid, etc.
What are the four sources of metabolic acid?
1. Carbonic acid from cellular respiration (CO2 and H20 combine into carbonic acid which dissociates into H+ and bicarbonate).
2. Incomplete oxidation of carbohydrates and fatty acids. Occurs when O2 is low (exercise) and lactic acid is formed. These acids can't be blown off.
3. Metabolism of proteins. Sulfuric acid is produced from sulfur containing amino acids. Phosphoric acid is produced from phosphoproteins. Can't be blown off.
4. Metabolism of phospholipids and nucleic acids produces phosphoric acid. Can't be blown off.
What are the three lines of defense against acid changes from fastest to slowest?
1. Buffers
2. Respiration
3. Proton excretion in kidneys
Where are the two main locations for phosphate buffering?
Intracellularly and in the urine. Still very minor role.
What is the main controller of ventilation rate?
CO2 concentration in the blood which is detected as protons in the medulla.
What is the Henderson-Hasselbalch equation pertaining to bicarbonate and CO2 concentrations?
pH=6.1+log(HCO3- / .03xPco2)
What happens if a large amount of fixed acid is present in the blood?
Lungs will respond by blowing off excess acid however this also depletes bicarbonate therefore reducing the buffering system.
If the buffering system and respiration system get overloaded, how do the kidneys help control pH?
They excrete protons into the filtrate (remember this is tied to sodium absorption). Protons complex with ammonia and phosphate. This processes also generates bicarbonate to restore buffering system.
What can happen to body pH with respiratory problems?
CO2 can build up and create an excess of carbonic acid. Kidneys will respond by excreting protons. This also generates bicarbonate to be used as a buffer.
What metabolic disorders can lead to excess acidity?
Many however renal disease (can't secrete protons), diabetes mellitus (ketoacids), and circulatory shock are common (decreased respiration and therefore lactic acid formation).
How pH affected in excess ventilation?
Excess CO2 is blown off resulting in alkalosis. Kidneys respond by slowing proton excretion.
How can renal disease lead to acidosis?
Inability to excrete protons.
How can diabetes mellitus lead to acidosis?
Excess production of ketoacids.
How can circulatory shock lead to acidosis?
Inadequate oxygen to tissues can result in formation of excess lactic acid. The same occurs with extremely heavy exercise.
How can diarrhea lead to acidosis?
Bicarbonate is excreted thus lowering the buffering capacity.
What are sources of metabolic alkalosis?
Ingestion of excess bicarbonate (antacids), vomiting.
How can vomiting lead to alkalosis?
Removal of acid found in stomach contents leads to net gain of bicarbonate (because every hydrogen ion from oxynitic cells also results in a bicarbonate ion).
What is the anion gap?
Because cations equal anions, occasionally there will be sources of anions present in the body that are not screen for in normal tests. The concentration of cations - concentration anions equals the concentration of these unknown anions.
Decreased pH, increased carbon dioxide and increased bicarbonate is what type of disturbance?
Respiratory acidosis.
Decreased pH, decreased carbon dioxide, and decreased bicarbonate is what type of disturbance?
Metabolic acidosis.
Increased pH, increased carbon dioxide, and increased bicarbonate is what type of disturbance?
Metabolic alkalosis.
Increased pH, decreased carbon dioxides, and decreased bicarbonate is what type of disturbance?
Respiratory alkalosis.