Acid-base Balance2

Question 1

What is the role of the respiratory mechanism in acid-base balance?

Answer 1

The respiratory mechanism contributes by eliminating or retaining CO₂. It helps regulate blood pH through the exchange of gases during external respiration.

Question 2

How does external respiration impact blood gases?

Answer 2

During external respiration in the lungs, oxygen (O₂) is exchanged for carbon dioxide (CO₂) between alveolar air and blood. O₂ binds to hemoglobin, forming oxyhemoglobin (O₂Hb arterial).

Question 3

What stimulates peripheral and central chemoreceptors?

Answer 3

A fall in pH (acidosis) stimulates peripheral and central chemoreceptors. These receptors are located in arteries, the aorta, and the central nervous system (CNS).

Question 4

How does the body respond to pH changes

Answer 4

The body adjusts respiration (breathing rate and depth). If pH decreases (more acidic), respiration increases to remove excess CO₂. If pH increases (more alkaline), respiration decreases to retain CO₂.

Question 5

Under what conditions might assisted ventilation be necessary

Answer 5

Pathological conditions affecting the response to chemoreceptor stimulation (e.g., impaired respiratory drive) may require assisted ventilation to maintain proper blood gas levels.

Question 6

explain what the kidney does during acidosis.

Answer 6

Excretion of acids is increased and that of base is conversed

Question 7

what 3 mechanisms are employed in renal excretion of acid and conservation

Answer 7

1. Na+ - H+ exchange
2. Production of ammonia (NH3) and excretion of NH4+
3. Reclamation of HCO3-

Question 8

Explain the significance of Na+-H+ exchanger

Answer 8

Using the Na+-H+ exchanger, the kidney extrudes H+ ions into the tubular fluid in exchange for Na+ ions. (This exchange is enhanced in acidosis and inhibited in alkalosis)

Question 9

What role do potassium ions play in renal acid-base balance?

Answer 9

Potassium ions compete with hydrogen ions (H⁺) in the renal tubular sodium-hydrogen exchanger. They affect the exchange of H⁺ for sodium (Na⁺), impacting urine acidity and body fluid pH.

Question 10

How does a high intracellular potassium level affect this exchange?

Answer 10

When intracellular potassium levels are high, more potassium is exchanged for sodium instead of hydrogen. This leads to increased urine acidity and decreased body fluid acidity

Question 11

What happens when there is potassium depletion regarding acid-base balance?

Answer 11

Potassium depletion results in more hydrogen ions being exchanged for sodium. As a consequence, urine becomes more acidic, and blood becomes more alkaline.

Question 12

Which conditions are associated with increased urine acidity due to potassium depletion?

Answer 12

1. Acidosis
2. Hypokalemia alkalosis.

Question 13

What happens when if the intracellular K+ level of renal tubular cells is high

Answer 13

More K+ and less H+ are exchanged for Na+.

Question 14

What role do renal tubules play in acid-base balance?

Answer 14

Renal tubules are involved in acid-base balance by producing ammonia (NH₃) from amino acids, particularly glutamine. This process occurs in the kidneys.

Question 15

How does ammonia contribute to acid-base regulation?

Answer 15

Ammonia (NH₃) dissociates into ammonium ions (NH₄⁺) and free ammonia (NH₃). The ratio of NH₄⁺ to NH₃ depends on the pH of the urine. At normal pH, most of the ammonia exists as NH₄⁺.

Question 16

How does ammonia enter the tubular lumen from renal cells?

Answer 16

Ammonia gas (NH₃) diffuses across the cell membrane into the tubular lumen. There, it combines with hydrogen ions (H⁺) to form ammonium ions (NH₄⁺), which are excreted in urine

Question 17

What is the significance of acidic urine pH in renal acid-base balance?

Answer 17

Acidic urine pH favors the formation of ammonium (NH₄⁺), which remains trapped in the tubular urine. This contributes to the excretion of hydrogen ions (H⁺) and helps regulate acid-base balance.

Question 18

How much NH₄⁺ production in the tubular lumen accounts for hydrogen ion excretion?

Answer 18

In normal individuals, NH₄⁺ production in the tubular lumen accounts for the excretion of approximately 60% of the hydrogen ions (H⁺).

Question 19

Can you explain the chemical processes depicted on the right side of slide number 14? Lec 4b

Answer 19

The chemical processes involve the formation of ammonium (NH₄⁺) from ammonia (NH₃) in the renal tubules. This process helps regulate urine acidity and overall acid-base balance.