Acid-Base Flashcards
1
Q
What 7 things cause respiratory alkalosis:
A
- Hyperventilation
- Anxiety
- High altitudes
- Pregnancy
- Fever
- Hypoxia
- Initial stages of pulmonary emboli
2
Q
What does pH and CO2 look like in respiratory alkalosis:
A
pH: increase
CO2: decrease
3
Q
What does pH and HCO3 look like in metabolic alkalosis:
A
pH: increase
HCO3: increase
4
Q
What does pH and CO2 look like in respiratory acidosis:
A
pH: decrease
CO2: increase
5
Q
What does pH and HCO3 look like in metabolic acidosis:
A
pH: decrease
HCO3: decrease
6
Q
What 3 things cause metabolic alkalosis:
A
- Loss of gastric juices
- Potassium wasting diuretic (loss of H)
- Overuse of antacids
7
Q
What 6 things cause respiratory acidosis:
A
- Drugs overdose
- Pulmonary edema
- Chest trauma
- Neuromuscular disease
- COPD
- Airway obstruction
8
Q
What 6 things cause metabolic acidosis:
A
- Shock
- Sepsis
- Diarrhea
- Renal failure
- Salicylate OD
- Diabetic ketoacidosis
9
Q
A single unit pH change reflects how much in [H]?
A
10 fold change
10
Q
Small changes in pH reflect relatively what changes in [H]?
A
Large changes
11
Q
Physiological pH changes affect in what 2 ways?
A
- Protein activity (enzymes and transporters)
2. Membrane function
12
Q
What are the 3 different physiological acids?
A
- Volatile acid (CO2)
- Metabolic intermediates
- Acidic, non-volatile end products
13
Q
Complete oxidation of biological fuels produces CO2 which combines with water to form carbonic acid
A
Volatile Acid (CO2)
14
Q
Many intermediates in fuel metabolism are carboxylic acid:
Lactic acid, acetoacetate, beta-hydroxybutyrate
A
Metabolic intermediates
15
Q
Sulfuric acid and phosphoric acid
A
Acidic, non-volatile end products
16
Q
Metabolic activity generates roughly how much H+ per day?
A
15,000 mmol H+
17
Q
What is required in order to maintain serum and intracellular pH values what in acceptable ranges?
A
Buffers
18
Q
What is the primary buffer system and where is it used?
A
Bicarbonate-carbonic acid - used in all extracellular fluids
19
Q
Buffer is a mixture of what 2 things?
A
Weak acid and conjugate base
20
Q
The kidney can do what with the bicarbonate buffer system?
A
Add or remove HCO3- or alter serum H+
21
Q
Normal value of pH, PCO2, HCO3-, ion gap?
A
7.4/40/24/12
22
Q
Will the concentration of anions always equal concentration of cations?
A
Yes
23
Q
What is the major cation present in anion gap?
A
Na
24
Q
What are the major anions in the anion gap?
A
Cl and HCO3
25
What is the anion gap?
Difference between [Na] and the sum of [Cl] and [HCO3]
26
What could be 6 other miscellaneous anions?
1. L or D lactate
2. Ketones
3. Salicylate
4. Pyroglutamate
5. Metabolic products of toxic alcohols
6. Retained non-volatile acids of renal failure
27
What 2 things happen when large quantities of non-volatile acids accumulate in serum like lactic acidosis and ketoacidosis?
1. Reduce serum bicarbonate levels because protons that dissociate from weak acids combine with serum bicarbonate
2. Conjugate bases of weak acids contribute as ‘other anions’ to ion gap
28
What is the result when large quantities of non-volatile acids accumulate in the serum?
Larger than normal ion gap
29
Is it normal for bicarb and CO2 to be synergistic?
No
30
4 causes of respiratory alkalosis (low PCO2)?
1. Hyperventilation
2. Hypoxia
3. CNS disease
4. Sepsis
31
4 causes of metabolic alkalosis (high HCO3)?
1. Vomiting, nasogastric suction
2. Diuretic use
3. Excess mineralocorticoid activity
4. Posthypercapnia (high serum CO2)
32
4 causes of respiratory acidosis (high PCO2)?
1. Hypoventilation
2. Neuromuscular disorders
3. Acute airway obstruction
4. Impaired lung function (severe pneumonia, pulmonary edema, thoracic cage injury, chronic lung disease)
33
4 causes of metabolic acidosis (low HCO3)?
1. Ketoacidosis (diabetic, alcoholic)
2. Lactic acidosis (anaerobic metabolism)
3. Salicylates (secondary effect)
4. GI bicarbonate loss (diarrhea)
34
What are the 3 anion gap metabolic acidoses?
1. Ketoacidosis (diabetic, alcoholic)
2. Lactic acidosis (anaerobic metabolism)
3. Salicylates (2ndary effect)
35
Nonanion gap metabolic acidoses result from what?
Renal or GI loss of bicarbonate; will increased serum chloride levels
36
Presence of ion gap >20 mEq, even when a patient is alkalosis or has a normal serum pH, is high predictive of what?
Anion gap metabolic acidosis
37
What is the mnemonic for remembering causes of ion gap acidosis?
KULT
Ketoacidosis (DKA, alcoholic ketoacidosis, starvation)
Uremia (renal failure)
Lactic acidosis
Toxins (ethylene glycol, methanol, paraldehyde, isoniazid, salicylates)
38
What 3 things decrease in ESRD pts?
1. Hematocrit
2. HCO3
3. pH
39
What are the death limits of pH?
6.8-7.8
40
Metabolism of macronutrients produces what?
Significant volatile acid load (CO2) and smaller nonvolatile acid load
41
The body principally uses what 3 systems to buff 15,000 mEq/d of acid
1. Rapid buffering in the ECF by HCO3 and phosphate
2. Rapid pulmonary exhalation of CO2
3. Slow renal excretion of H using NH3 and phosphate as buffers
42
What foods are alkali (2)?
Fruity and veggies
43
What foods are acidic (3)?
Meat, grains, and dairy
44
What system has the kidneys and lungs work together?
Bicarbonate buffer system (most abundant ECF physiochemical buffer)
45
Bicarbonate buffer system is shifted in what direction to remove CO2 from lungs?
Left due to increased CO2.
46
What do the kidneys do in the bicarbonate buffer system?
Filter HCO3 and combine it with secreted H
47
Hederson-hasselbalch equation to determine the pH in buffer system by focusing on what relationship?
HCO3 and CO2
48
What is the metabolic component in the Henderson-hasselbalch equation?
HCO3 (kidney)
49
What is the respiratory component in the Henderson hasselbalch equation?
CO2 (lungs)
50
Normal value of H?
40
51
Normal value of pH?
7.4
52
Normal value of PaCO2?
40
53
Normal value of HCO3?
24
54
What kind of disturbance with less time means generally less compensation?
Acute
55
What kind of disturbance with more time means generally more compensation?
Chronic
56
Compensation helps normalize pH but does it help to correct the original disturbance?
NO
57
How much of the filtered load of HCO3 is typically excreted in the urine?
0%
58
What 3 things promotes H secretion/HCO3 reabsorption?
1. Acidosis (high PCO2 or H / low HCO3)
2. Aldosterone or AngII / low ECFV (more Na/H activity)
3. Hypokalemia
59
Normal urine output is what pH?
Acidic (5.5)
60
How much why is there no net aid secretion or generation?
Because hydrogen ions are continually recycled in this reclamation process
61
What happens with bicarb and H in the kidneys?
Bicarb is reabsorbed and H is secreted
62
PT and TAL secrete H how much?
~80%
63
When is H secretion + filtered bicarb = carbonic acid used?
During normal or acidosis
64
How does AngII affect the PT and TAL?
Increase Na/H transporter activity
65
How does increased acid load affect PT and TAL?
Increase HCO3 transporters
66
AngII is worried about Na reabsorption or H secretion?
Na reabsorption and permissive with H secretion
67
What does the H-K-ATPase (type A intercalated cells) do in the collecting duct?
K reabsorbed and H secreted
68
When is the H-K-ATPase pump used in collecting duct?
During normal and acidosis
69
H-K-ATPase activity increase in states of what and what does it cause?
Hypokalemia and lead to alkalosis
70
How does aldosterone affect the H-K-ATPase in collecting duct?
Increase H-ATPase, K/H exchanger and Na/K pump
| More important when chronically elevated
71
Increasing renal H secretion tends to promote what?
Hypokalemia
72
Does bicarb serve as the renal base and why?
No because we need to reabsorb it and actually produce more of it
73
Why is there little free H filtered from the glomerulus capillaries to Bowman’s space?
Because the normal [H] is 40
74
Most H in the tubular lumen has built up from what?
Tubular secretion
75
The removal of H is the biochemical equivalent of bicarbonate generation but we need somewhere to put the H that is secreted into the tubule. What 2 things can they get put into?
1. Phosphate buffer
| 2. Ammoniagenesis
76
Does phosphate and ammonia buffers increase or decrease during chronic acidosis?
Increase
77
What are the 2 fixed (non-volatile) acid excretion?
1. Filtered HPO4 to H2PO4 formation in the PT and CD
| 2. Secreted NH4 and NH3 to NH4 in the PT and CD
78
What are the first line of defense, and are considered the primary filtered urinary buffers?
Phosphate and sulfate
79
What adapts to meet demand and becomes the primary buffer?
Ammonia
80
Large acid loads are excreted mainly in the form of what?
Ammonium
81
Both systems of urinary buffers do what?
Free up bicarb for reabsorption
82
Acid in the urine is mainly in the form of what 2 things?
Ammonium ions and phosphoric acid (~70 mEq/d of fixed acid)
83
Renal venous blood contains more what than the renal arterial blood?
HCO3
84
As GFR declines, the risk of what increases?
Metabolic acidosis
85
If you want to excrete acid (normal and acidosis) what 5 things can occur?
1. Freely filter HCO3 at glomerulus
2. Reabsorb 80% of filtered HCO3 in PT
3. Reabsorb additional 19% of HCO3 in TAC, DT, CD
4. Secrete some H, H2PO4, and NH4 in DT, CD
5. Excrete acidic urine containing H2PO4 and NH4
86
If you want to excrete base (alkalosis) what 5 things occur?
1. Freely filter HCO3 at glomerulus
2. Reabsorb 80% of filtered HCO3 in PT
3. Reabsorb less bicarb from HCO3 TAC, DT, CD (10%)
4. Secrete some HCO3 in DT, CD
5. Excrete alkaline urine containing more HCO3 than usual
87
pH: <7.4
HCO3: <24
Metabolic acidosis
88
pH: <7.4
HCO3: <24
PCO2: <40
Respiratory compensation
89
pH: <7.4
PCO2: >40
Respiratory acidosis
90
pH: <7.4
PCO2: >40
HCO3: >24
Renal compensation
91
pH: >7.4
PCO2: <40
Respiratory alkalosis
92
pH: >7.4
PCO2: <40
HCO3: <24
Renal compensation
93
pH: >7.4
HCO3: >24
Metabolic alkalosis
94
pH: >7.4
HCO3: >24
PCO2: >40
Respiratory compensation
95
How would the kidneys deal with ECF fixed acid load?
Recover virtually all filtered bicarb
96
The kidneys excrete acid by attaching secreted hydrogen ions to filtered or synthesized urinary bases like?
Phosphate (normally)
| Ammonium (particularly during acidosis)
97
During acidosis, most acid is excreted by converting what to what, and then what?
Glutamine to bicarb and ammonium then excreting the ammonium and returning the bicarb to blood
