Glossary of Acid-Base Imbalances (Patho)

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Acids are _____ by bases
What does pH represent?
concentration of H+ in the blood
Lower pH means...
more acidic (higher concentration of H+)
Higher pH means...
less acidic (lower concentration of H+)
What are volatile acids?
can form a gas
- can be eliminated by lungs
What are the sources of volatile acids?
metabolism of glucose & fat
What are nonvolatile acids?
can't be converted to form a gas
- ex. HCO3-
- excreted by kidneys

What are the sources of nonvolatile acids?
anaerobic glycolysis and P-protein/P-lipid metabolism
What is the importance of pH? (List 3)
1. changes the ionization of molecules [add or removes charge (+ or - )]
2. ionization - affects ability to cross CM
3. ionization - affects the shape of the molecule

What are 3 key mechanisms in regulating pH?
1. Buffering System (H2CO3-)
2. Respiration System (ventilation)
3. Renal System

What is the normal pH range?
What is the most important acid-base reaction to remember?
H+ + HCO3- H2CO3 H2O + CO2
What are the 3 major buffering systems?
1. Bicarbonate Buffer System (key)
2. Protein Buffer System (all plasma proteins & IC proteins such as Hgb)
3. Phosphate & Ammonia (key in nephron to promote excretion)

What are 3 characteristics of the respiratory system?
1. If bicarbonate system does not correct imbalance within a few minutes, the respiratory system will be activated
2. Focuses on maintaining CO2 levels
3. consists of hyperventilation (blowing off CO2) & hypoventilation (retaining CO2)

What are 3 characteristics of the renal system?
1. if the bicarbonate buffer system and respiratory systems do not correct imbalances, the renal system will be activated
2. Slower initiation (few hours) / slow acting (several days to restore balance)
3. Primary mechanism: HCO3- is reabsorbed
Secondary mechanism: H+ excreted (if imbalance still persists after all possible HCO3- is reabsorbed)

Which system corrects imbalances?
Renal System
Which systems compensate for imbalances?
Buffering System & Respiratory System
What is acidosis?
too much acid
What is alkalosis?
too much base relative to acid
If H+ concentrations are high, pH levels are _____.
If H+ concentrations are low, pH levels are _____.
What is compensation?
- partial compensation: pH remains abnormal
- full compensation: pH is normal but all other values are abnormal
What does ABG stand for?
Arterial Blood Gas
What are 5 arterial blood gas values?
1. pH
2. HCO3-
3. pCO2 or PaCO2
4. pO2
5. O2 saturation

Why are arterial blood gases used for analysis as opposed to venous blood?
Because venous blood is used blood and is deoxygenated. Arteries carry O2.
What are 4 acid-base disturbances?
Metabolic Disturbances:
1. Metabolic Acidosis
2. Metabolic Alkalosis
Respiratory Disturbances:
3. Respiratory Acidosis
4. Respiratory Alkalosis

What are primary metabolic defects?
disturbances that arise from either a problem with H+ or HCO3- ions
What are primary respiratory defects?
disturbances that arise from a problem with CO2
What is metabolic acidosis and what is the primary defect?
- occurs when there is an increase of any metabolic acid or decrease of HCO3-
- primary defect: high [H+] relative to HCO3-
What are 4 causes of metabolic acidosis?
1. Hypoxia - (anaerobic metabolism to generate ATP --> buildup of lactic acid --> increased [H+])
2. Diabetes complication (ketone bodies)
3. Aspirin poisoning (acetylsalicylic acid)
4. Diarrhea (loss of HCO3- from lower GI)

What is hypoxia?
lack of O2 supply reaching body tissues
What are 3 characteristics of the bicarbonate buffer system?

1. Chemical rxn is reversible
2. if equation is not in equilibrium, H2CO3 will break down in the direction of the lower concentration
3. Occurs rapidly (within minutes)

If there is too much H+, there will be a _____ shift.
Why is HCO3- decreased during metabolic acidosis?
- first H+ ions produced will be neutralized by HCO3-
- eventually too many H+ produced and HCO3- gets used up
- therefore, HCO3- decreases

Why is CO2 decreased during metabolic acidosis?
high [H+] causes an increase in CO2 which stimulates respiratory system to hyperventilate (blow off more CO2) resulting in decreased CO2 levels (partial compensation)
What are 5 S&S of metabolic acidosis?
1. Kussmaul's respirations (deep, gasping)
2. Restlessness
3. Seizures
4. N/V (nausea/vomiting)
5. Hyperkalemia (initial buffering: K+ inside exchanged with H+ outside)

What is metabolic alkalosis and what is the primary defect?
- occurs when there is a loss of acid or excess intake of base
- primary defect: low [H+] relative to HCO3-
What are 3 causes of metabolic alkalosis?
1. Excessive vomiting (lose H+)
2. NG (nasogastric) suctioning (lose H+)
3. Excessive intake of alkaline drugs (antacids)

What are ABG findings for metabolic alkalosis?
- lose H+ ions --> excess HCO3-
- increased pH since [H+] is lower
- CO2 is initially decreased but then it increases to keep the reaction going to the left (hypoventilation occurs - retains CO2) - partial compensation

What are 3 S&S of metabolic alkalosis?
1. Disorientation
2. Muscle twitches
3. Tetany - muscle spasms

***NOTE: with metabolic imbalances, the pH, HCO3-, & CO2 move in the ______ direction.

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