Acid Base 1A

Question 1

Physiologic acids originate from the metabolism of:

Answer 1

• fats and carbohydrates (H2CO3)
• protein (H2PO4; H2SO4)

Question 2

Carbonic acid (H2CO3) is a product of:

Answer 2

metabolism of fats and carbohydrates

Question 3

Steps in the formation of carbonic acid (H2CO3) from the products of fat and carbohydrate metaboilism:

(Equation)

Answer 3

Question 4

What enzyme catalyzes the formation of H2CO3 from CO2 and H2O?

Answer 4

carbonic anhydrase (CA)

Question 5

Products of protein metabolism/oxidation of sulfur-containing AAs:

Answer 5

• H2PO4-
• H2SO4-

ALSO BUFFERED BY BICARBONATE

Question 6

Equation for determining physiologic plasma pH:

Answer 6

pH = 6.1 + log([HCO₃^-]/0.03PCO₂)

Question 7

Plasma pH is derived from the ratio of what two molecules?

Answer 7

• HCO₃^- : PCO₂
• pH = 6.1 + log([HCO₃^-]/0.03PCO₂)

Question 8

Plasma pH is dependent on what two molecules?

Answer 8

• HCO3-
• PCO2 (CO2)

Question 9

Normal arterial blood pH range:

Answer 9

7.38 - 7.44

Question 10

Abnormally elevated pH level and associated condition:

Answer 10

>7.44

alkalemia

Question 11

Abnormally low pH level and associated condition:

Answer 11

<7.38
acidemia

Question 12

The four primary acid-base perturbations:

Answer 12

1. respiratory acidosis
2. respiratory alkalosis
3. metabolic acidosis
4. metabolic alkalosis

Question 13

Acid-base perturbations can exist singly or as combined pathologies. What is the only impossible combination?

Answer 13

respiratory alkalosis with respiratory acidosis

Question 14

Metabolic and respiratory acid-base disorders result from:

Answer 14

Blood HCO3- and/or PCO2 imbalances

Question 15

Normal compensation for a metabolic acid-base disorder (metabolic acidosis or metabolic alkalosis):

Answer 15

Lungs blow-off or retain CO2

Question 16

Normal compensation for a respiratory acid-base disorder (respiratory acidosis or respiratory alkalosis):

Answer 16

• Kidneys alter HCO3-, H+, K+ reabsorption or excretion

Question 17

Derangements in plasma pH are usually caused by:

Answer 17

• an underlying condition.
• underlying condition needs to be corrected in order to resolve acid-base imbalance.

Question 18

Morbidity and mortality of acid-base disorders depends on:

Answer 18

• the risk associated with underlying disorder causing the acid-base imbalance.

Question 19

Respiratory acidosis results from:

Answer 19

• impaired ability to expire CO2.
• CO2 equates with H+ load, pH decreases as plasma CO2 (i.e. PCO2) rises above normal.

Question 20

Hypercapnia is:

Answer 20

• excessive carbon dioxide in the bloodstream.
• typically caused by inadequate respiration.

Question 21

A nonvolatile acid (fixed acid) is:

Answer 21

• an acid produced in the body from sources other than carbon dioxide.
• not excreted by the lungs.

Question 22

The nonvolatile acids are excreted by:

Answer 22

the kidneys

Question 23

All acids produced in the body are nonvolatile except:

Answer 23

• carbonic acid, which is the sole volatile acid.
• excreted as CO2 by lungs.

Question 24

Charge of fixed (non-volatile) acids:

Answer 24

• Net negative charge; anionic.
• Buffered by renal HCO3- retention and H+ secretion.

Question 25

The endogenous buffering time line:

Answer 25

* **Seconds:** plasma and interstitial bicarbonate buffers H+. * **Minutes:** bone & intracellular buffers buffer H+. * **Hours:** interstitium and plasma cells swap extracellular H+ for intracellular K+. * **Several hours:** changes in ventilation. * **Days:** kidneys mediate H+ excretion and increase bicarbonate secretion.

Question 26

Normal plasma bicarbonate (HCO3-) level:

Answer 26

24 meq/L.

Question 27

Normal plasma PCO2 level:

Answer 27

40 mm Hg.

Question 28

Acidemia can be caused by either:

Answer 28

* increased PCO2 (respiratory) * decreased HCO3- (metabolic)

Question 29

Draw algorithm to determine whether respiratory or metabolic acidemia.

Answer 29

Question 30

Alkalemia can be caused by either:

Answer 30

* decreased PCO2 (respiratory) * increased HCO3- (metabolic)

Question 31

Draw algorithm to determine whether respiratory or metabolic alkalemia.

Answer 31

Question 32

Two ways RBCs remove/carry CO2:

Answer 32

1. CO2 diffuses through the plasma membrane of a RBC, and: * CO2 + H2O (CA catalyzed) → H2CO3 → H+ + HCO3-. * HCO3- swapped out of RBC for extracellular Cl-. * H+ build-up causes conformational change in Hb. * H+ binds to deoxyHb. 2. CO2 diffuses through the plasma membrane of a RBC, and directly binds to deoxyHb to form carboxyhemoglobin.

Question 33

Steps in how RBCs release oxygen and HCO3- into plasma:

Answer 33

1. CO2 diffuses through the plasma membrane of a RBC, and: * CO2 + H2O (CA catalyzed) → H2CO3 → H⁺ + HCO3-. * **HCO3- swapped out of RBC for extracellular Cl-.** * **H+ build-up causes conformational change in Hb. Oxygen released into plasma.** * H+ binds to deoxyHb.

Question 34

Normal respiratory rate (resting adult):

Answer 34

16/min

Question 35

Tachypnea:

Answer 35

elevated respiratory rate (\>16/min)

Question 36

Bradypnea:

Answer 36

depressed respiratory rate (\<16/min)

Question 37

Process of CO2 expiration at alveolus:

Answer 37

* RBC gets to alveolus. Oxygen diffuses into RBC. * Increased oxygen tension in RBC causes hemoglobin conformation change from deoxyhemoglobin to oxyhemoglobin: 1. **HHb + O2 → O2Hb + H⁺ → H⁺ + HCO3- → H2CO3 → H2O + CO2 (expired)** 2. **CO2Hb → O2Hb + CO2 (expired)**

Question 38

The two rightward reactions in RBCs at the alveoli that lead to CO2 expiration:

Answer 38

1. **HHb + O2 → O2Hb + H⁺ → H⁺ + HCO3- → H2CO3 → H2O + CO2 (expired)** 2. **CO2Hb → O2Hb + CO2 (expired)**

Question 39

Steps in how decreased ventilations lead to respiratory acidosis:

Answer 39

1. Less CO2 blown-off. 2. Hypercapnia occurs. 3. Increased CO2 impedes the rightward reaction in RBC at alveoli. 4. Plasma [H+] increases. 5. High plasma H+ leads to low pH. 6. Respiratory acidosis.

Question 40

Draw algorithm for determining whether compensated or non-compensated respiratory acidosis:

Answer 40

* respiratory acidosis * low pH + high PCO2 (\> 40)

Question 41

Compensation rule one: acute respiratory acidosis:

Answer 41

HCO₃^- up 1 unit for every PCO₂ up 10 units

Question 42

Compensation rule two: chronic respiratory acidosis:

Answer 42

HCO₃^- up 4 units for every PCO₂ up 10 units

Question 43

Steps in how increased ventilations lead to respiratory acidosis:

Answer 43

1. More CO2 blown-off. 2. Reaction in RBCs at alveoli driven to the formation of CO2 + H2O. 3. Plasma H+ lost as H2O. 4. Low H+ leads to elevated pH. 5. Respiratory alkalosis.

Question 44

Draw algorithm for determining whether compensated or non-compensated respiratory alkalosis:

Answer 44

* respiratory alkalosis: * high pH + low PCO2

Question 45

Compensation rule three; acute respiratory alkalosis:

Answer 45

HCO3- down 2 for PCO2 down 10

Question 46

Compensation rule four; chronic respiratory alkalosis:

Answer 46

HCO3- down 5 for every PCO2 down 10

Question 47

The four respiratory compensation rules:

Answer 47

* Acute respiratory acidosis: “Up 1 for 10” * Chronic respiratory acidosis: “Up 4 for 10” * Acute respiratory alkalosis: “Down 2 for 10” * Chronic respiratory alkalosis: “Down 5 for 10”