Acidosis/Alkalosis

Question 1

pH of the body depends on the ratio of what?

Answer 1

[HCO3] / [H2CO3]

Question 2

What pH constitutes acidosis?

Answer 2

pH<7.35

Question 3

How does the body become acidotic?

Answer 3

1) metabolic acidosis: where the pH is < 7.35 where the primary defect is a decrease in plasma [HCO3]
2) respiratory acidosis: This is a pH<7.35 where the primary defect is an increase in the paCO2

Question 4

What are a few causes of metabolic acidosis?

Answer 4

1) excess acid production like keto acid production in diabetes mellitus
2) severe diarrhoea
3) renal failure

Question 5

What is the compensatory response to metabolic acidosis?

Answer 5

• buffering in the ECF by HCO3-, Pi, and plasma proteins
• bone releases Ca2+ as salt in exchange for H+ ions
• ICF- H+ is titrated by HCO3-, Pi and histidine groups on proteins

Question 6

what is the respiratory response to metabolic acidosis?

Answer 6

the plasma HCO3 concentration has decreased, therefore blood pH has fallen and the lungs try to bring about a proportionate decrease in the paCO2- increasing ventilation

Question 7

What is the renal compensation to metabolic acidosis?

Answer 7

reabsorption of all filtered HCO3-, secretion of H+ by nephron and increased excretion of H+ bound to urinary buffers (Pi and creatinine), increased NH4+ production

Question 8

what is Kuss Maul breathing?

Answer 8

observed increased respiration due to acidosis

Question 9

what are the causes of respiratory acidosis?

Answer 9

overall inadequate ventilation

1) depression of respiratory centre
2) paralysis of respiratory muscles
3) lung damage from pulmonary oedema in CV or lung disease

Question 10

What is the compensatory response to respiratory acidosis?

Answer 10

buffering of H+ mainly in the ICF (acute phase)

when pCO2 rises, CO2 moves into cell where it combines with H2O to form H2CO3, then HCO3, and H+

H+ buffered by intracellular protein

Question 11

what is the effect of chronic and acute acidosis on K+ excretion?

Answer 11

Acute acidosis = decreases K+ excretion

Chronic acidosis= increases K+ excretion

Question 12

what is the effect of acidosis on bones?

Answer 12

when chronic, demineralization of bones occurs (osteomalacia)

b/c the Ca2+ is released from bone to exchange for H+ present in the ECF

Question 14

What pH denotes alkalosis?

Answer 14

pH> 7.45

Question 15

What is metabolic alkalosis?

Answer 15

the primary defect cuasing pH increase is an increase in plasma HCO3 concentration

Question 16

what is the cause of respiratory alkalosis?

Answer 16

decrease in paCO2 often due to hyperventilation

Question 17

what are some causes of metabolic alkalosis?

Answer 17

• vomiting
• ingestion of volatile base (antacids)
• volume contraction (haemorrhage) which increases Na+ reabsorption

Question 18

what respiratory action compensates for metabolic alkalosis?

Answer 18

1) plasma [HCO3] has increased and therefore blood pH has increased
2) the lungs try to bing out the proportionate increase in paCO2- therefore hypoventilation occurs

Question 20

What is the renal compensation to metabolic alkalosis?

Answer 20

• reduced reabsorption of HCO3-
• decreased excreton of titratable acid and NH4+

Question 21

what are some causes of respiratory alkalosis?

Answer 21

hyperventilation (panic attacks)

Question 22

What is the intracellular and renal response to alkalosis?

Answer 22

intracellular = buffering in the ICF

renal = filtered load and excretion of HCO3- increased, decreased exretion of titratable acid and NH4+

thus, decreased net acid excretion and HCO3- appears in urine

Question 23

what are some effects of alkalosis?

Answer 23

irritability/confusion - if severe hypocalcaemic tetany

Question 24

Why does blood alkalosis lead to tetany?

Answer 24

because your albumin wants H+ when it’s in the alkalotic state, but obviously H+ isn’t available, it binds instead to calcium. This decreased free serum Ca2+ increases the neuronal membrane permeability to sodium, so you have an easy initiation of action potentials - leads to tetany

Question 25

What is trousseaus sign of tetany ?

Answer 25

Question 26

Why does hyperventilation lead to fainting/dizziness?

Answer 26

the decrease in pCO2 cuases cerebral ischaemia resulting in dizziness and fainting

Question 27

How do you analyze an acid base disorder nature/origin?

Answer 27

1) examine pH - is it acidic or basic?
2) if acidic- examine the value for pCO2, it will be high if the acisosis is respiratory - examine the value for plasma HCO3 concentration and it will be low if the acidosis is metabolic
3) if alkalosis- examine the value for pCO2- it will be low if the alklaosis is respiratory - examine the value for plasma [HCO3] and it will be high if the alkalosis is metabolic

Question 28

Analyze the following acid base disorders

Answer 28

patient A= metabolic acidosis

Patient B = metabolic Alkylosis

patient C= respiratory acidosis