Acid-Base Disorders

Question 1

How do brain and arterial receptors respond to a blood pH change leading to acidosis?

Answer 1

Responds via increasing respiration rate –> decreases blood CO2 –> decreases blood H2CO3 –> increases pH

*this leads to restoration of homeostasis

Question 2

Name the three blood buffers involved in damping H+ changes

Answer 2

1) Carbonic anhydrase buffer
2) Phosphate buffer
3) Hemoglobin

Question 3

How does hypoventilation affect blood pH?

Answer 3

Hypoventilation causes an increase in blood C02 –> increase blood H2CO3 –> low blood pH or acidemia.

Question 4

List the 4 steps involved in bicarbonate supply via the renal system (for when the blood pH is high):

Answer 4

1) Na+ - H+ antiporters reabsorb Na+ from filtrate into renal tubular cells
2) Tubular cells produce Bicarbonate ions and shunt them to peritubular capillaries
3) CO2 is converted to carbonic acid which dissociates into is converted to bicarbonate & H+
4) Hco3- is reabsorbed into peritubular capillaries/blood (and H+ is excreted into urine).

Question 5

What two chemical pathways can excreted H+ ions take when being excreted into urine?

Answer 5

HPO4 + H = H2PO4

NH3 + H = NH4

Question 6

What is the most effective way to track daily excretion of Hydrogen? Why?

Answer 6

Measure the amount of ammonium present in urine; The amount of HPO4 available to bind H+ is relatively constant.

Question 7

Which form of transport is the reabsorption of bicarbonate ions into the peritubular capillaries?

Answer 7

Passive transport

Question 8

What is ammonium’s primary source in the kidneys and where is it predominately located?

Answer 8

Glutamine from the peritubular capillaries; the proximal tubular cells

Question 9

How does bicarbonate reabsorption in the distal convoluted tubule differ form that of the proximal convoluted tubule?

Answer 9

DCT:

• for H+ excretion: H+ ATPase (instead of Na-H antiporter)
• for HCO3 reabsorption: HCO3-Cl antiporter (instead of Na-HCO3 antiporter)
• **leads to limited HCO3 reabsorption

Question 10

What is the CO2 to HCO3 ratio?

Answer 10

1:20

Question 11

In the event of respiratory alkalosis, a [bicarbonate] of ____ indicates a mixed disorder.

Answer 11

<10 mmol/L

Question 12

In the event of respiratory acidosis, a [bicarbonate] of ____ indicates a mixed disorder.

Answer 12

> 40 mmol/L

Question 13

In the event of metabolic acidosis, a [CO2] of ____ indicates a mixed disorder.

Answer 13

<10 mmHg

Question 14

In the event of metabolic alkalosis, a [CO2] of ____ indicates a mixed disorder.

Answer 14

> 60 mmHg

Question 15

What is the normal range for blood pCO2?

Answer 15

35-45 mmHg

Question 16

What is the normal range fro blood HCO3?

Answer 16

20-26 mmol/L