PHYSIOLOGY - Renal Function (Acid Base Balance)

Question 1

What are the three main systems the body uses to achieve acid base balance?

Answer 1

Intra- and extracellular buffers
Respiratory system
Renal system

Question 2

What is unique about renal acid base balance compared to the other methods used by the body?

Answer 2

Renal acid base balance is the only system that removes non-volatile acids formed during metabolism

Question 3

What are the three methods exerted by the renal system to achieve acid base balance when the body is in acidosis?

Answer 3

Reabsorption of HCO3-
Production of HCO3-
Excretion of H+

Question 4

What are the three methods exerted by the renal system to achieve acid base balance when the body is in alkalosis?

Answer 4

Excretion of HCO3-

Question 5

How much does urine pH vary?

Answer 5

Urine pH varies between 4.5 - 8.5

Question 6

In which regions of the renal tubules does reabsorption of HCO3- occur?

Answer 6

Reabsorption of HCO3- occurs at the level of the proximal convoluted tubule (PCT) and the thick ascending loop of Henle

Question 7

In which regions of the renal tubules does production of HCO3- occur?

Answer 7

Production of HCO3- occurs within the intercalated cells of the distal convoluted tubule (DCT) and the collecting duct

Question 8

What are the three main methods of H+ secretion and excretion in the filtrate?

Answer 8

• Na+/H+ counter transport system on the apical membrane of the proximal convoluted tubule
• ATPase H+ transporter system on the apical membrane of the intercalated cells
• ATPase H+/K+ counter-transporter system on the apical membrane of the intercalated cells

Question 9

Though H+ is secreted into the filtrate by the renal tubules, why is there so little H+ in the urine?

Answer 9

There is so little H+ in the urine because most of it is buffered and neutralised

Question 10

What are the most predominant buffers in the filtrate?

Answer 10

Bicarbonate
Phosphate
Ammonia

Question 11

What is the collective name for phosphate and ammonia acting as buffers?

Answer 11

Titratable acids

Question 12

What is so beneficial about ammonia as a buffer compared to the other buffers present in the filtrate?

Answer 12

Ammoniagenesis can be regulated by the body and are not dietary dependent like phosphate

Question 13

Where does ammoniagenesis occur within the renal tubules?

Answer 13

Ammoniagenesis occurs within the proximal convoluted tubule (PCT) and the collecting duct