L6: renal acid-base balance Flashcards
acid=
H+ donating substance
base=
H+ accepting substance
what blood vessels have a higher PH
Arteries
why are veins more acidic
carry more CO2 –> carbonic acid
3 things that regulate H+ conc in blood
chemical buffers
respiratory centre
renal system
where are chemoreceptors located
carotid arteries
aortic arch
medulla
what can respiration do when there is excess CO2
breath faster
which part of the kidneys does acid base balance happen
collecting tubules
what balance happens in the principal cells
H2O and Na+
what do carotid and aortic bodies detect
O2
what does the medulla detect
CO2/ decrease Ph
what do intercalated cells do
acid base balance
what cell responds to ADH by making more aquaporin channels
principal cells
how is filtered HCO3- reabsorbed
by forming H2O and CO2 which can enter the cell via carbonic anhydrase
in the cell what happens to the H2O and CO2
H+ is excreted in filtrate HCO3- enters the peritubular capillary
when does H+ secretion stop
when pH is lower than 4.5
normal urine pH =
6-8
what amino acid is used to generate new HCO3-
glutamine
what happens to the H+ when urine pH is lower than 4.5
HPO4- is used to accept h+ –> H2PO4- which is excreted
what is glutamine metabolised to
NH4+ and HCO3-
what happens to the NH4+ from glutamine
secreted into filtrate
what happens to HCO3- from glutamine
enters the peritubular capillaries
2 types of acidosis
respiratory acidosis
metabolic acidosis
reason for respiratory acidosis=
impaired ventilation
reasons for metabolic acidosis (3)
- diarrhoea
- renal disease
- uncontrolled DM/ starvation
cause for respiratory alkalosis
rapid ventilation
cause for metabolic alkalosis
vomiting
what do you measure in metabolic ph change
HCO3
what do you measure in respiratory pH change
PCO2
alkalosis pH=
> 7.45
acidosis pH=
<7.35
why are infants at greater risk of abnormal pH (5)
- low volume on lungs
- excessive fluid shift
- high metabolic rate
- higher water loss rate
- inefficient kidneys
why are older people at higher risk (3)
decrease in total body volume
slow homeostasis
unresponsive thirst ques
which control of pH is fastest
lungs
