Acid Base 1

Question 1

What is a normal [H+] in the blood?

Answer 1

40 nEq/L

If take the -log of this value, get 7.4ish –> where normal blood pH determination comes from

Question 2

What is the range of normal blood pH?

What is the definition of acidemia and alkalemia?

Answer 2

7.37 - 7.42

Acid: pH < 7.37

Alkalosis: pH > 7.42

Question 3

Many proteins are [acids or bases].

Answer 3

Bases

Question 4

What is the pH in the following locaitons in the body?

Answer 4

Question 5

pH < […] or pH > […] is incompatible with life.

Answer 5

6. 8
7. 0

Question 6

• What are 3 common sources of “acid production” in the body?
• How are each of these sources of acid secreted?

Answer 6

• CO₂ (CO₂ + H₂O <=> H₂CO₃ <=> H⁺ + HCO₃^-) –> exhaled
• From diet (sulfuric and phosphoric acids) –> buffered and secreted in kidney
• Lose HCO₃^- in stool –> loss of base is equivalent to gain of acid –> buffered and secreted in kidney

Question 7

• Is H₂CO₃ a strong or weak acid?
• Is there more H₂CO₃ or H⁺ in the blood?

Answer 7

• Weak
• H₂CO₃

Question 8

How much acid is produced/ingested daily?

Answer 8

-80mEq

Question 9

What are the immediate buffering compounds in the extracellular fluid? (Blood)

Answer 9

HCO₃^-

HPO₄^-2

Question 10

What compounds act as buffers in the intracellular fluid?

Answer 10

Organic phosphates

Proteins

Hemoglobin

Question 11

What are all the ways that we can buffer changes in pH?

Answer 11

Question 12

Where in the body is carbonic anhydrase concentration high?

Answer 12

• renal tubule epithelial cells
• walls of alveoli
• RBC

Question 13

What is the definition of a buffer?

Answer 13

Question 14

How can you manipulate the hendersen hasselbach eqn to relate to the bicarbonate buffering system using pCO2 and [HCO3-]?

Answer 14

Question 15

pCO2 levels are controlled by the […] and HCO3- levels are controlled by the […]

Answer 15

Lungs

Kidney

Question 16

Metabolic acidosis and metabolic alkalosis are driven by what?

Answer 16

[HCO3-]

Low [HCO3-] leads to increasing [H+] and thus decreasing pH (acidosis)

High [HCO3-] leads to decreasing [H+] and thus increasing pH (alkalosis)

Question 17

Respiratory acidosis and alkalosis are driven by what?

Answer 17

pCO2

High pCO2 –> increases [H+] –> decreases pH

Low pCO2 –> decreases [H+] –> increases pH

Question 18

In acute respiratory acidosis, what do the tissues do to buffer the increasing CO2?

Answer 18

Increasing pCO2 –> increasing [H+] –> respiratory acidosis –> CO2 can enter tissues and be acted upon by carbonic anhydrase if the tissue has that enzyme and broken down ultimately into H+ and HCO3-. H+ can bind to Hb to be buffered and HCO3- enters blood to buffer excess H+ in blood from increasing CO2.

Question 19

In chronic respiratory acidosis, what does the body do to try and keep the blood pH from being too low?

Answer 19

Increase reabsorption of HCO3- from the urine and increase excretion of H+ in the urine

Question 20

In acute respiratory alkalosis, what do the tissues do to buffer the decreasing CO2?

Answer 20

Decreasing pCO2 –> decreasing [H+] –> respiratory alkalosis –> H+ in tissues can combine with HCO3- in tissues to form H2CO3 which can then be converted to CO2 via carbonic anhydrase in tissues. This generates more CO2 to prevent the pH from rising too high (decreases drive of le chatlier’s principle to push eqn to left)

Question 21

In an acute respiratory disturbance, the buffering occurs […] whereas in a chronic disturbance the buffering occurs […]

Answer 21

Intracellularly

By the kidneys

Question 22

What is the difference between metabolic acidosis and respiratory acidosis?

Answer 22

Metabolic - adding H+ to blood (food, loss of HCO3- in stool)

Respiratory - caused by changes in breathing that thereby alter the pCO2

Question 23

In metabolic acidosis, how does the body prevent pH from dropping too low?

Answer 23

Immediately, the increasing H+ is buffered** by the bicarb buffer system (Combines with HCO3- to make H2CO3 and then that’s converted to CO2). Within minutes - hours, will start to hyperventilate because increasing CO2 triggers chemoreceptors in carotid body/aortic body and central system to increase respiration rate. This is the **compensation that occurs by the lungs.

Question 24

In metabolic alkalosis, how does the body prevent the pH from rising too much?

Answer 24

Can be caused by vomiting (loss of H+ from stomach). Immediately, the decreasing H+ is buffered by the bicarb buffer system (CO2 in blood will be driven to form H+ and HCO3-). Within minutes - hours, will start to hypoventilate because decreasing CO2 triggers chemoreceptors in carotid body/aortic body and central system to decrease respiration rate. This is the compensation that occurs by the lungs. This will increase CO2, drive eqn back to right to replenish H+ and HCO3-. Overtime, this can lead to a build up of HCO3- since you only lost H+ but that can be compensated for by the kidneys.

Question 25

For every 1 mEq/L drop in [HCO3-] (and thus also H+), what is the expected compensation by the lungs?

Answer 25

decrease pCO2 by 1.5mmHg

Question 26

Phosphate Buffer System

• Where is this buffer system most active?
• Manipulation of henderson hasselbach for this buffer system?

Answer 26