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level: Level 1

Questions and Answers List

level questions: Level 1

QuestionAnswer
What is the concentration of H+ at pH of 7.440 nmol/litre
Where is hydrogen carbonate reabsorbed mainly80% of it is reabsorbed in the PCT Using the mechanism of Na+/H+ exchanger 3
What is basically the mechanism that hydrogen carbonate is reabsorbedFirst carbonic anhydrase II breaks H+ and HCO3- inside the cell, then there is an exchange of H+ being secreted and Na+ being reabsorbed H+ then reacts with HCO3- in the lumen to form H2CO3 where membrane bound carbonic anhydrase IV to facilitate the formation of H20 and CO2 This then enters the cell where using carbonic anhydrase II it forms HCO3- and H+ and the cycle restarts HCO3- then leaves the cell into the blood via the 3HCO3--Na+ symporter
If there was an increase in HCO3- concentration or a decrease in pCO2, what would happenthe ratio to increase and cause the pH to increase → alkalosis
What would happen if a drop in HCO3- or a increase in pCO2would cause the ratio to decrease and pH to decrease leading to acidosis
What are the 2 mechanisms to buffer the excess H+ to maintain adequate H+ secretion in the nephronReaction with ammonia to form ammonium ( 60% ) Reaction of H+ with dibasic phosphate (HPO4 2-) to form monobasic phosphate (HPO4 - )
How do you calculate the anion gap[Na+ ] – ([Cl- ] + [HCO3 - ])
Metabolic acidosis with high anion gap indicates whatDue to increased organic acids in the bloodstream e.g. lactic acidosis, diabetic keto acidosis
What does a normal anion gap indicateThis is due to loss of HCO3- The kidneys compensate for this loss by secreting chloride so the serum remains electroneutral Bicarbonate loss can be due to renal tubular acidosis and diarrhoea
What does acidosis lead to in ECF [K+]Increase drive of K+ out of cells Also leads to less K+ to be excreted Can lead to hyperkalaemia
What can alkolosis lead to in ECF [K+]More K+ to enter the cells More K+ to be excreted by the kidneys Can lead to hypokalaemia
When a person ingests potassium, what are the cellular eventsK+ is absorbed Insulin is secreted K+ moves into the cells Some H+ moves out but due to extra HCO3- in the stomach, remains neutral No hyperkalaemia
In a person with diabetic ketoacidosis, what are the cellular eventsNo insulin --> cells produce ketones and less K+ enters the cells ECF H+ rises, then H+ enters the cells and K+ leaves But due to osmotic diuresis, excess electrolytes are lost hence ECF K+ does not rise Once you give insulin, K+ moves back into the cells and ketone production is reduced Without insulin, there is a risk of hypokalaemia