Renal Lec 7 Flashcards
high [H+]= …. pH
low pH (acidic)
low [H+]= …. pH
high pH (basic/alkaline)
pH= (equation)
=log (1/[H+])= -log [H+]
pH for ECF is between
7.35 to 7.45
acidosis
arterial plasma pH < 7.35
alkalosis
arterial plasma pH > 7.45
why is balance of H+ important for body functions?
small changes in pH causes porteins to change shape
- enzymes: shape changes can alter their activity
- changes in neuronal activity
- coupled to K+ imbalances
- irregular cardiac beats
pH of ECF that lead to death
pH< 6.8
pH> 7.8
acid (def.)
release H+ in solution
Base (def.)
accepts H+ in solution
volatile acid (body)
carbon dioxide
volatile (def.)
exporative at normal temperatures
nonvolatile acids (body)
-organic and inorganic acids from other sources than CO2
nonvolatile acids (examples)
phosphoric acid
sulfuric acid
what produces sulfuric acid in body?
metabolism of sulfur-containing a.a (cysteine, methionine)
what produces hydrochloric acid in body?
metabolism of lysine, arginine and histidine
buffer (def.)
-any substance that binds to H+
buffer is composed of
weak acid and its conjugate base
buffers modify/adjust
-the change in pH following the addition of acids or bases
extracellular buffer system
CO2/HCO3-
intracellular buffer system
phosphate ions/proteins
example of intracellular buffer (blood)
Hemoglobin
H+ is buffered by both
extracellular/ intracellular fluid
organs responsible for balancing hydrogen ion concentration within narrow range
kidneys and lungs
lungs (short-term/long-term) balancing hydrogen ion concentration
short-term
kidneys (short-term/long-term) balancing hydrogen ion concentration
long-term
respiratory H+ imbalances
- hyperventilation
- hypoventilation
- respiratory malfunction
↑ {H+] … ventilation
stimulates
↓ [H+] … ventilation
inhibits
alkalosis decrease of plasma [H+] -kidneys
kidneys excrete more bicarbonate
acidosis increase of plasma [H+] -kidneys
kidneys synthesize new bicarbonate and send it to blood
reabsorption of HCO3- is dependent on
H+ secretion
most of HCO3- is …. in normal conditions
reabsorbed
reabsorption of HCO3- (location)
proximal tubule, ascending loop of henle, CCD
H+ secretion is an
active process
transport of H+ is different depending on tubule segments (3 types)
- H+/ATPase
- H+/K+ ATPase
- Na+/H+ ATPase
reabsorption of HCO3- mechanism 1
in tubular cell: water + carbon dioxide through carbonic anhydrase = carbonic acid– dissociates H+, HCO3-
H+ secreted into tubular lumen (forms carbonic acid with HCO3- in lumen), HCO3- secreted into interstitial fluid
no HCO3- in lumen to bind H+ - mechanism 1
extra H+ binds to HPO42-
still net gain of HCO3- in plasma
reabsorption of HCO3- mechanism 2
- cells from proximal tubule are only involved
- uptake of glutamine from filtrate or plasma
- NH4+/HCO3- are formed inside the cells
- NH4+ is actively secreted via the Na+/NH4+ counter transport into the lumen
- HCO3- added to plasma
Respiratory acidosis (def.)
– increased blood PCO2
Respiratory acidosis occurs
– as a result of decreased ventilation
– occurs in emphysema
kidney compensates by (Respiratory acidosis)
- secreting H+ and lowers plasma [H+]
Respiratory alkalosis (def.)
decreased blood PCO2
Respiratory alkalosis occurs
–as a result of hyperventilation
- happens in high altitude
kidney compensates by (Respiratory alkalosis)
– excreting HCO3
Metabolic acidosis occurs
– in diarrhea (loss of bicarbonate ions)
– severe exercise
– diabetes mellitus
Metabolic acidosis results
– results in increased ventilation
– results in increased H+ secretion
Metabolic alkalosis occurs
after prolonged vomiting
Metabolic alkalosis results
– in decreased ventilation
– in increased HCO3- excretion
