L7- renal and endocrine systems Flashcards
(42 cards)
normal blood pH
7.35-7.45 (7.4)
fatal blood pH
<6.8 or >7.8
pH equation
-log[H+]
what is a buffer
any subsstance which can reversibly bind H+
Major intracellular buffers
Phosphate and proteins
Source of H ion gain
Generation of H+ from CO2
Production of non-volatile acids from metabolism of proteins and other organic molecules
Gain of H+ due to loss of HCO3 in diarrhoea or other non gastric gi fluids
Loss of HCO3 in urine
Source of H+ loss
Use of H+ in metabolism of various organic anions
Loss of H+ in vomit
Loss oh H+ in urine
Hyperventilation
Respiratory acidosis cause
Retention of CO2
Respiratory alkalosis cause
Excessive elimination of CO2
Metabolic acidosis
Gain of H+
Metabolic alkalosis
Loss of H+
Integration of homeostatic controls in terms of H+ ion
Respiratory and kidneys work together to balance H+ conc
Respiratory system is very rapid and keeps conc from changing too much.
Kidneys are more slowly responding and can eliminate the imbalance
Renal mechanisms of controlling H+
Kidneys eliminate or replenish H+ from the body by altering HCO3- conc
When plasma H+ conc increases, kidneys don’t excrete HCO3- in urine and kidney tubular cells produce more HCO3- and add it to plasma.
When plasma H+ conc decreases, kidneys excrete large quantities of HCO3-
HCO3- & H+ secretion occurs in
Proximal tubule, ascending loop of Henley and cortical collecting duct.
When is new HCO3- produced
During acidosis
How is new HCO3- produced
Secreted ht combines with other non - bicarbonate buffers
Causing A net gain of bicarbonate in the plasma.
Renal metabolism of glutamine & new HCO3-
All filtered HCO3 - is reabsorbed. Glutamine metabolised to HCO3- and NH4+
NH4+ secreted and excreted → net gain of HCO3- in the plasma.
Response to acidosis.
Enough ht secreted to reabsorb all filtered HCO3-, still more Mt secreted in urine bound to non-bicarbonate buffers → new - HCO3 -in plasma
Tubular glutamine metabolism and ammonium excretion are enhanced → ↑ HCO3 - in plasma
Urine = highly acidic.
Response to acidosis.
Rate of il ion secretion not enough to reabsorb HCO3 - so its secreted in urine so no excretion of non-bicarbonate urinary buffers
Tubular glutamine metabolism& ammonium excretion ↓ so no new HCO3 -
Urine is alkaline.
juxtaglomerular cells are
intrarenal baroreceptors- meaning they are modified smoth muscle cells in the afferent arteriole that detect changes in blood pressure ( when blood pressure is low thse cells are stretched less so secrete more renin
juxtaglomerular cells are innervated by
sympathetic renal nerve, which stimulate renin secretion
where is the macula densa located
end of the ascending limb of the loop of henle
what does macula densa detect
Na+ ( or Cl- ) in the tubular fluid
decreased salt concentration increases secretion of
renin
