Acid Base Balance

Front 1

1. The arterial blood pH is maintained at app._______________________pH

Back 1

7.35-7.45

Front 2

2. What is the physiologic carbonic acid equation?

Back 2

H+ + HCO3--H2CO3---H20 + CO2

Front 3

3. What follows if there is a drop in pH(increase in H+ concentration)?

Back 3

This leads to an increase in CO2 which can be exhaled from the lungs. The kidneys excrete additional hydrogen, and attempt to replete bicarbonate stores.

Front 4

4. how fast is the pulmonary response to acid base imbalance?

Back 4

It is rapid, seconds to minutes, where the kidneys response is slower, hours to days.

Front 5

5. Can the lungs excrete only volatile acids?

Back 5

Yes. All nonvolatile acids must be excreted via the kidneys.

Front 6

6. What is a volatile acid?

Back 6

An acid produced from carbon dioxide (CO2). It can be excreted by the body by ventilation (colloquially, “blowing off CO2”). Carbonic acid is a volatile acid.

Front 7

7. What is a non volatile acid?

Back 7

A nonvolatile acid (also known as a fixed acid or metabolic acid) is an acid produced in the body from sources other than carbon dioxide, and is not excreted by the lungs. They are produced from e.g. an incomplete metabolism of carbohydrates, fats, and proteins. All acids produced in the body are nonvolatile except carbonic acid, which is the sole volatile acid. Common nonvolatile acids in humans are lactic acid, phosphoric acid, sulfuric acid, acetoacetic acid, and beta-hydroxybutyric acid.

Front 8

8. Where is the primary site of acid excretion in the kidney?

Back 8

It is in the distal collecting duct, where H+ is secreted into the tubular lumen where it combines with Ammonia(NH3) to form ammonium(NH4+), which is excreted in the urine.

Front 9

9. The kidneys regulate acid base through the reabsorption and reabsorption and regeneration of bicarbonate, primarily in the proximal tubule. True/False

Back 9

True.

Front 10

10. What is a mechanism that can lead to the development of metabolic acidosis?

Back 10

Excess production of endogenous acids can exceed the ability of the kidneys to excrete H+. This occurs in advanced renal failure, where the kidneys lose their ability to generate ammonium.

Occasionally, this can happen even with intact renal function. (lactic acidosis from tissue ischemia or in diabetic ketoacidosis)

Front 11

11. What is another mechanism that may result in metabolic acidosis?

Back 11

Ingestion of exogenous acids (methanol, or ethylene glycol).

It can develop from the loss of bicarbonate. failure of bicarbonate absorption(proximal renal tubular renal acidosis), or from GI loss of HCO3 fluids, such as diarrhea, pancreatic fistula.

Front 12

12. In the kidney, where is potassium regulated?

Back 12

It is regulated in the distal collecting duct where it is secreted into the lumen in response to aldosterone mediated Na+ reabsorption.

Front 13

13. Aldosterone is a primary hormonal regulator of K+. True/False

Back 13

True. Hyperkalemia is a signal for aldosterone release, while hypokalemia provides negative feedback for such release.

Front 14

14. Can hypokalemia result due to intracellular potassium shifting?

Back 14

Yes. (Alkalosis, use of beta agonist therapy, extrarenal losses(diarrhea or renal losses.

Front 15

15. In general, increased delivery of Na+ to the distal tubules/ collecting duct will result in what?

Back 15

This would result in increased K+ secretion witht the most common causes of renal K+ wasting being diuretic use and osmotic kaliuresis.

Front 16

16. How may Conn's syndrome influence K+ absorption?

Back 16

Hyperaldosteroneism, either primary from an adrenal tumor(Conn's) or secondary(hyperrenninemic), hyperaldosteroneism frequently presents with hypokalemia due to unregulated Na+ reabsorption with resultant secretion of both K+ and H+.

Front 17

17. How does the kidney play an important role in Ca+ and phosphate homeostasis?

Back 17

The kidney is the site of 1 alpha hydroxylation or 24 hydroxylation of 25-hydroxycholecalciferol, the hepatic metabolite of vitamin D3. This produces calcitriol, or 1,25 dihydroxy vitamin D, the active vitamin D form. This increases calcium absorption from the gut.

Front 18

18. the kidney is a site of action of PTH. True/False

Back 18

True. This results in Ca+ retention and phosphate wasting in the urine.