13. Acid-Base Homeostasis Flashcards Preview

EMS - Mechanisms of Disease > 13. Acid-Base Homeostasis > Flashcards

Flashcards in 13. Acid-Base Homeostasis Deck (16):
1

what is the purpose of buffering systems?

to maintain normal pH in the body

2

what buffering systems can be found in the body?

1. haemoglobin
2. bicarbonate
3. phosphate
4. proteins
5. ammonia
6. Misc. organic acids

3

what does the homeostasis of H+ ions require?

a balance between H+ production and regeneration of HCO3-

4

what are the sites of acid-base metabolism?

lungs
kidneys
GI tract
liver

5

which organs are the main sources of excretion of acid?

lungs and kidneys
breathing is controlled through hydrogen ion concentration

6

what causes a right shift in the the oxygen-haemoglobin dissociation curve?

increased 2,3 diPG
Acidosis, increase of H+ ions
temperature

7

what are the problems that could arise with regards to acid-base pathology?

metabolic acidosis
metabolic alkalosis
respiratory acidosis
respiratory alkalosis

8

what compensatory mechanisms exist to counteract acid-base pathology?

1. respiratory
2. renal bicarbonate regeneration (takes about 1-2 days)
3. hepatic shift between urea synthesis and ammonia excretion
urea cycle change (takes about a week)

9

what are the causes of metabolic acidosis?

1. increased H+ formation
2. acid ingestion
3. reduced renal H+ excretion
4. loss of bicarbonate

10

what are the causes of metabolic alkalosis?

1. generation of bicarbonate by gastric mucosa
2. renal regeneration of HCO3- in hypokalaemia
administration of bicarbonate

11

what are the consequences of metabolic alkalosis?

K+ enters cells and uric
PO4 enters cells
respiratory suppression

12

How does respiratory acidosis result?

CO2 retention due to
1. inadequate ventilation
2. parenchymal lung disease
3. inadequate perfusion

13

how does respiratory alkalosis result?

increased CO2 excretion due to excessive ventilation producing alkalosis

14

what stimulates increased H+ formation?

diabetic or alcoholic ketoacidosis
lactic acidosis
poisoning
inherited organic acidosis

15

how does diabetic ketoacidosis result?

hyperglycaemia
pre-renal uraemia due to osmotic diuresis
hyperketonaemia
increased FFA

16

how does acidosis result in an alcoholic?

NAD+ depletion, causing a thiamine deficiency
thiamine is a PDH co factor
enhanced glycolysis for ATP formation
leto-acids secondary to counter-regulatory hormones
result - profuse vomiting