13. Acid-Base Homeostasis Flashcards
what is the purpose of buffering systems?
to maintain normal pH in the body
what buffering systems can be found in the body?
- haemoglobin
- bicarbonate
- phosphate
- proteins
- ammonia
- Misc. organic acids
what does the homeostasis of H+ ions require?
a balance between H+ production and regeneration of HCO3-
what are the sites of acid-base metabolism?
lungs
kidneys
GI tract
liver
which organs are the main sources of excretion of acid?
lungs and kidneys
breathing is controlled through hydrogen ion concentration
what causes a right shift in the the oxygen-haemoglobin dissociation curve?
increased 2,3 diPG
Acidosis, increase of H+ ions
temperature
what are the problems that could arise with regards to acid-base pathology?
metabolic acidosis
metabolic alkalosis
respiratory acidosis
respiratory alkalosis
what compensatory mechanisms exist to counteract acid-base pathology?
- respiratory
- renal bicarbonate regeneration (takes about 1-2 days)
- hepatic shift between urea synthesis and ammonia excretion
urea cycle change (takes about a week)
what are the causes of metabolic acidosis?
- increased H+ formation
- acid ingestion
- reduced renal H+ excretion
- loss of bicarbonate
what are the causes of metabolic alkalosis?
- generation of bicarbonate by gastric mucosa
- renal regeneration of HCO3- in hypokalaemia
administration of bicarbonate
what are the consequences of metabolic alkalosis?
K+ enters cells and uric
PO4 enters cells
respiratory suppression
How does respiratory acidosis result?
CO2 retention due to
- inadequate ventilation
- parenchymal lung disease
- inadequate perfusion
how does respiratory alkalosis result?
increased CO2 excretion due to excessive ventilation producing alkalosis
what stimulates increased H+ formation?
diabetic or alcoholic ketoacidosis
lactic acidosis
poisoning
inherited organic acidosis
how does diabetic ketoacidosis result?
hyperglycaemia
pre-renal uraemia due to osmotic diuresis
hyperketonaemia
increased FFA
