Systems Pathology: disorders of acid base balance Flashcards Preview

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Flashcards in Systems Pathology: disorders of acid base balance Deck (12)
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Acid production and excretion

The body is a net acid producer
Carbonic acid-> oxidation of carbs and fats to co2 and water
Lactic acid and ketoacidosis-> partial oxidation of carbs and fats, non volatile- excreted by kidneys
Sulphuric acid and phosphoric acid-> metabolism of sulphur and phosphate, non volatile so excreted by kidneys

1

Acid homeostasis

ECF [H+] 35-45 pH 7.45
Temporary measure-> nothing has been removed
Co2+h2oh2co3 H+ +hco3
Co2 excreted/retained by lungs
Hco3 retainined, generated or excreted by kidneys

2

Consequences of acidosis

Hyperkalaemia
Hyperventilation
Depression of consciousness
Coma
Death

3

Consequences of alkalosis

Hypokalaemia
Hypocalcaemia -> muscle cramps, tetany, parathesia

4

Respiratory acidosis

Co2 retention -> low pH/normal-> hco3 high normal/high
Causes:
COPD
Suppression of resp system
Upper airway obstruction
Resp muscle disease
Compensation-> metabolic-> renal hco3 generation and H excretion-> high hco3

5

Respiratory alkalosis

Low CO2-> normal/high pH-> low/normal hco3
Hyperventilation->
Anxiety
Cerebral disease
Pulmonary embolus
Hypoxia
Compensation-> metabolic-> renal hco3 excretion

6

Metabolic acidosis

Low hco3 -> low pH->pco2 normal/low
Increased acid generation-> lactic, keto toxins
Impaired acid excretion-> renal failure
Bicarbonate loss-> diarrhoea
Compensation-> resp-> hyperventilation
-> kidney-> hco3 production

7

Plasma anion gap

One negative charge balances one positive charge
Na and K provide more than 90% of plasma cation
Cl and hco3 80% of plasma anions
Anion gap= (Na+K) - (hco3+Cl)
Normally 14-20

8

Metabolic acidosis high anion gap

Acute or chronic renal failure
Ketosis
Lactic acidosis
Intoxication
Renal tubular acidosis-> impaired hco3 production
Acetazolamide-> inhibits CD in tubules-> impaired hco3 formation
GI disease

9

Metabolic alkalosis

High hco3-> high pH -> pco2 raised
Iatrogenic-> base administration, diruetics
Loss of acid from stomach
Hyperaldosteronism
Compensation-> resp-> hypo ventilation

10

Primary and compensatory changes summary

Metabolic acidosis-> low pH, low pco2, low hco3
Metabolic alkalosis-> high, high, high
Resp acidosis-> low, high, high
Resp alkalosis-> high, low, low

11

Bases excess

The amount of H+ ions that would be required to return the pH to normal
Mirrors hco3
Normally +\- 2
>3 metabolic alkalosis
<-3 acidosis

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