acid base balance Flashcards
what is an acid
any compound which forms protons in solution
what is a base
any compound which combines with H+ in solution(then termed alkali)
what is acididosis
low plasma pH
alkalosis
high plasma pH
what is normal pH range
7.35-7.45 avg 7.4
what do fluctuations of protons have effects on
excitability of muscle and nerves
enzyme activities
K+ levels
how do changes in protons affect K+ levels
too many/few ions on either side may affect the cotransport system
sources of acid/alkali
volatile acids
fixed acids
what is a volatile acid
will leave the solution
produced by oxidative metabolism
what is a fixed acid
acid that don’t leave solution
generated by catabolism aa, phospholipids and nucleic acids
what systems are involved to keep H+ levels
blood and tissue buffer
respiration
renal
where are buffers present
blood
extra/intracelluar fluid
urine
examples of buffers
HCO3-
hamoglobin
explain carbonic acid use as a buffer
formed/broken down to water and carbon dioxide
also formed from H+ and bicarbonate ion (HCO3-)
i.e. mopping up the H+ ions
what is the bicarbonate reserve
maintenance of a level of bicarbonate ions
sodium bicarbonate dissociates into sodium and bicarbonate ions
explain haemoglobin buffering????
left over CO2 combines with water forming carbonic acid
dissociated to form proton and carbonate ions
released by erythrocytes to exchange for chloride ions
phosphate buffering
able to pick up or release protons
acts as weak acid
limitiations of buffering
only temporary solution to acid base imbalance
H+ ions not eliminated
supply of buffers limited§
respiratory acid base control
can eliminate or retain CO2
CO2 can be used to make carbonic acid
what would be there response to acidosis
stimulate brain and arteriole receptors increase respiration decrease in blood CO2 decease in carbonic acid increase in pH (homeostasis restored)
Renal acid base control
3rd line
only mechanism to excrete fixed acids
regulates levels of bicarbonate
regulating existing bicarbonate ions
cells line lumen of proximal tubule
protons generated and exchanged for sodium across membrane
filtrate from blood contains carbonate ions
binds with protons to form bicarbonic acid
enzyme able to act on and to form water and CO2 taken up by tubular epithelial cells
CO2 and water combine to form bicarbonate again
other systems to remove protons in kidney
new dicarbonic acid is generated (H20 +CO2)
dissociates into H+ and carbonic acid
h+ joined with phosphate ion to be excreted
or glutamine broken down into ammonia and bicarbonate
ammonia joins with H+ for amminum to be excreted
causes of acid base disturbances
metabolic acidosis - lactic alkalosis - intake of alkali respiratory acidosis - airway obstruction alkalosis - breathing too much
treatment
identify cause
use saline, potassium, dilute HCL, bicarbonate
