Urinary 4 Flashcards
(25 cards)
What are acid and bases?
acid are substances that releases H+
bases are substances that takes in H+
what is the pH range of blood
ideally it should be pH = 7.4
but it can range from 7.35 to 7.45
in humans our pH should be maintained between pH 6.8 to 8.0
what are the 4 buffering systems in the body?
1) bicarbonate buffering system
2) hemoglobin buffering system
3) phosphate buffering system
4) protein buffering system
what is acidosis and alkalosis
acidosis pH < 7.4 (too much co2/H+)
alkalosis pH > 7.4 (too much hco3-)
what are buffers?
buffers are substances that allows for binding of H+ or the release of H+ to ensure that pH is kept constant despite the addition of acid/bases
where are the 4 buffering systems found?
ICF
1) phosphate buffer
2) protein buffer
ECF
1) bicarbonate buffer
Blood
1) bicarbonate buffer
2) hemoglobin buffer
3) protein buffer
acid production in the body in physiological state
1) amino acid metabolism (release h2so4 & nh4+)
2) co2 formation due to metabolism
but because of the buffering system in our body, this allows for acid base regulation in which there is secretion of excess H+
the kidney regulate acid base balance by?
1) secretion of H+
2) reabsorption of hco3- (bicarbonate)
what is carbonic anhydrase and what does the inhibitors do?
carbonic anhydrase catalyzes the formation of h2co3 when there is a combination of co2 and h2o and vice versa when there is break down to h2co3 to become co2 and h2o
when h2co3 gets broken down into h+ and hco3-, carbonic anhydrase catalyzes the break down as well
with carbonic anhydrase inhibitors, this would result in depress pct with acid secretion > loss of bicarbonate and sodium in the urine > increase in lost of water
h+ secretion and hco3- reabsorption in the PCT
h+ + hco3- = h2co3 = co2 + h20
catalyzed by carbonic anhydrase
at the apical membrane there is the na+/h+ exchanger in which, h+ gets secreted with every 1 na+ that gets reabsorbed
at the basolateral membrane there is na+/hco3- co-transporter that allows for reabsorption of both na+ and hco3-
for every h+ secreted 1 molecule of na+ and hco3- is reabsorbed
h+ secretion and hco3- reabsorption in the late DCT (intercalated cells)
acid base regulation is the main function of the type A intercalated cells
apical membrane
1) h+ ATPase
2) h+/k+ exchanger
basolateral membrane
1) hco3-/cl- exchanger
under the influence of aldosterone, this would result in the increase h+ secretion by the h+ ATPase, the increase h+ secretion would result in the increase in hco3- reabsorption
what happens to the h+ secreted into urine?
urine can have a limiting pH of 4.5, anything that goes below 4.5 h+ can no longer be excreted
the amount of acid secretion depends on the urine pH
the presence of 3 buffering systems in the urine would help to expand the ability to excrete more H+ and also delay reaching the pH threshold of 4.5
the 3 buffering system in urine and where they are located at in the nephron
1) bicarbonate buffering system (mainly in PCT)
2) phosphate buffering system (mainly in distal tubules and collecting duct)
3) ammonia buffering system (mainly in PCT and DCT)
explain the 3 buffering systems in urine
1) bicarbonate buffering system (mainly in PCT)
hco3- + h+ = h2co3
even if large amount of H+ gets secreted it would not alter the pH and cause a drastic change as the H+ is within a complex
2) phosphate buffering system (mainly in distal tubules and collecting duct)
h+ + HPO4 2- = h2po4 -
h2po4- + na = NaHPO4
for every NaHPO4 that gets extracted, 1 hco3- is reabsorbed
3) ammonia buffering system (mainly in PCT and DCT)
NH3+ + H+ = NH4+
for every NH4+ that gets extracted, 2 molecules of hco3- is reabsorbed
how will these factors interfere with h+ secretion and hco3- reabsorption?
co2, angiotensin II, aldosterone, serum potassium levels and ECF vol
increase h+ secretion and hco3- reabsorption
1) co2 increase
2) angiotensin II increase
3) aldosterone increase
4) hypokalemia
5) ECF vol decrease
decrease h+ secretion and hco3- reabsorption
1) co2 decrease
2) angiotensin II decrease
3) aldosterone decrease
4) hyperkalemia
5) ECF vol increase
causes of metabolic acidosis
loss of bicarbonate due to
1) diarrhea
2) RTA renal tubule acidosis
H+ concentration increase due to
1) ingestion of calcium chloride (acidic substances)
2) reduce in h+ excretion, renal failure
3) increase in h+ production due to ischemia, lactic acid generation and diabetes ketosis
ischemia = no blood flow towards a region, and no oxygen supply this leads to the tissue undergoing anaerobic respiration. results in production of lactic acid
diabetes ketosis = due to not enough insulin, this would result in burning of lipids which produces keto acid
respiratory regulation of acid base balance
(increase ventilation vs decrease ventilation)
increase ventilation > increase in co2 extracted > decrease h+ concentration
decrease ventilation > decrease in co2 extracted > increase h+ concentration
causes of metabolic alkalosis
loss of H+ due to
vomiting (leads to lost of gastric juices)
hco3- increase because of
ingestion of ex antacids (especially in px with gastritis)
causes of respiratory acidosis
due to decrease in ventilation which leads to decrease in co2 release and this accumulation of h+
causes due to
1) lung diseases (severe pneumonia and severe asthma) blockage of the respiratory system results in decrease in release of co2
2) neuromuscular weakness results in respiratory muscle weakness
causes of respiratory alkalosis
due to increase in ventilation which leads to lost of co2 this reducing h+ concentration
causes due to
1) hyperventilation (to resolve, breathe into bag)
2) going to higher altitudes (reduce o2 so body tries to take in o2 but ends up expelling co2)
compensatory mechanism for respiratory acidosis
renal compensation
increase secretion of h+ and reabsorption of hco3-
compensatory mechanism for respiratory alkalosis
renal compensation
reduce h+ secretion and reabsorption of hco3-
compensatory mechanism for metabolic acidosis
increase expelling of co2
other compensatory mechanisms include
- reduce glomerular filtration of hco3-
compensatory mechanism for respiratory alkalosis
stop breathing to conserve co2 release but this is not a viable solution
other compensatory mechanisms include
- reduce h+ secretion
- reduce hco3- reabsorption
