Acid - base balance Flashcards Preview

September lectures yr 3 (2018) > Acid - base balance > Flashcards

Flashcards in Acid - base balance Deck (17)
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1
Q

What are the 2 basic challenges that confront the body systems for maintenance of acid base balance?

A

CO2 production: oxidative metabolism

Acid production: dietary phosphoproteins and sulphur containing proteins

2
Q

What are the extracellular buffers to H+?

A

bicarbonate = buffer system in ECF and erythrocytes and plasma
phosphate and proteins = mainly in the ICF but proteins in ECF can also buffer

3
Q

How does bicarbonate act as a buffer to H+?

A

in the DCT the high levels of CO2 can be taken up by the cells and join with H20 and then break down into H+ and HCO3-
- the H+ can be excreted in the tubular fluid and the HCO3- can enter the peritubular plasma

4
Q

What is a simplified version of the henderson-hasselbalch equation?

A

pH= HCO3/PCO2

5
Q

How can acidosis arise?

A

fall in HCO3 with normal PCO2

rise in PCO2 with normal HCO3

6
Q

How can alkalosis arise?

A

rise in HCO3 with normal PCO2

fall in PCO2 with normal HCO3

7
Q

How long dose respiratory compensation for metabolic acidosis/alkalosis take?

A

12-24 hours

8
Q

How long does metabolic compensation for respiratory acidosis/alkalosis take?

A

2-4 days

9
Q

What factors cause metabolic acidosis?

A

increased H+ load
decreased H+ secretion
Loss of bicarbonate

10
Q

What are some causes of increased H+ load?

A
ketoacidosis 
lactic acidosis 
drugs: salicylates
methanol 
ethanol 
ethylene glycol
11
Q

What are some causes of reduced H+ secretion?

A

renal failure
RTA
mineralocorticoid deficiency

12
Q

What are some causes of loss of HCO3?

A

GIT: diarrhoea
Renal: RTA

13
Q

What factors cause metabolic alkalosis ?

A

loss of H+

excessive HCO3 intake

14
Q

What are the causes of loss of H+?

A
vomiting
mineralocorticoid excess (cushing's, conns) bartters, severe K deficiency
15
Q

What are the causes of excessive HCO3 intake?

A

oral or IV therapy

16
Q

What are some causes of respiratory acidosis?

A
Lung disease:
- emphysema 
- bronchitis
- asthma 
Neuromuscular:
- guillain barre syndrome 
Central NS
- trauma
- infection 
- tumours 
Drugs
- sedatives
- anaesthetics
Mechanical ventilation
17
Q

What are some causes of respiratory alkalosis?

A

hyperventilation
pulmonary= pneumonia, asthma, CCF, embolism, mechanical ventilation

central - trauma, infection, tumours, septicaemia, liver failure, drugs (salicylates), hysterical

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