Phys 4 Flashcards
changes in pH are tightly regulated by what?
- buffer systems
- respiratory function
- renal processing of filtrate
What are the 3 chemical buffer systems?
- phosphate buffer system
- protein buffer system
- carbonic acid - bicarb buffer system
bicarb buffer system
- important in ECF
- bicarb converts a strong acid to a weak one
- carbonate converts a strong base to a weak base
phosphate buffer system
- monohydrogen phosphate ion converts a strong acid to a weak one
- dihydrogen phosphate ion converts a strong base to a weak one
- (think phosporylation)
protein buffer system
- carboxyl group of aa can release H
- amine group of aa can accept H
What happens when our physiologic buffer systems aren’t working adequately?
organ systems have to step in
normal process going on in the respiratory system
- CO2 produced by cells, transported in blood, eliminated by lungs
- exhalation = production
What happens in the respiratory system when CO2 exceeds elimination (i.e hypercapnia)
- central medullary detection of elevated H stimulates increase rate and depth of ventilation to unload CO2
- slower than chemical buffering but is more powerful
since the lungs only deal with carbonic acid via CO2 elimination, what deals with everything else?
- kidneys
- they deal w/ all other metabolic acids:
- phosphoric acids
- uric acid
- ketone bodies
metabolic acidosis
accumulation of the metabolic acids
what is a function that only the kidneys have?
regulation of alkaline substances and renewal of buffer systems
the most important renal mechanism for regulating acid-base balance of the blood involves what?
- excreting H
- conserving or generating HCO3-
(intercalating cells of collecting tubules can do opposite if needed)
secretion of H is a function of what?
tubular cells (PCT, DCT, collecting ducts)
what is responsible for renal secretion of H ions at the PCT?
- Na-H exchanger
- Na/bicarb symporter
Na-H exchanger
- where
- what it does
- at apical surface
- secretes H in exchange for Na
