1_Water In-Class Activity 2

Which amino acid side chain can function as an effective buffer at physiolgical pH, thereby allowing proteins such as hemoglobin to function as buffers?

• Histidine
• Glutamine
• Serine
• Aspartic acid
• Lysine

The pKa of dihydrogen phosphate is 7.2. What is the effective buffer range for this acid and its conjugate base?

• pH = 6.2-8.2

• pH = 6.7-7.7

• pH = 5.2-9.2

• pH = 7.0-7.4

Calculate the pH of a buffer that contains 0.25 M sodium acetate and 0.25 M acetic acid (pK_a 4.76). 

Mathematical Equivalence

ON

Answer explanation

pH = pKa when there are equal amounts of acid and base present

Could also calculate

pH = pKa + log B/A

pH = 4.76 + log (0.25/0.25)

pH = 4.76 + log (1)

pH = 4.76 + 0 = 4.76

What term is used to describe a blood pH less than 7.35?

• Acidosis
• Alkalosis
• Hyperprotonemia

• Hypoxia
• Hypoprotonemia

Calculate the blood pH plasma with a total CO₂ concentration of 30 mM and a [HCO₃^-] = 25.8 mM. Round to the nearest tenth.

Mathematical Equivalence

ON

Answer explanation

[H2CO3] = [CO2] - [HCO3-]

[H2CO3] = 30 mM - 25.8 mM = 4.2 mM

pH = 6.1 + log ( [HCO3-]/[H2CO3])

pH = 6.1 + log ([25.8]/[4.2]) = 7.0

You receive the attached lab results for one of your patients. What is the patient's BUN Creatinine ratio (mg/dL)? Round to the nearest tenth. Numerical response only.

Mathematical Equivalence

ON

Answer explanation

BUN/Cr = 46/4.1 = 11.2 mg/dL

Which of the following conditions can result in a lower than normal BUN/Creatinine Ratio?

• Dehydration
• Kidney stones
• Liver disease

• Diabetes insipidus
• High protein intake

You receive the below ABG for a patient. What is the patient's pCO2?

ABG: 7.40 / 40 / 90 / 25 / 98%

• 7.40 mmHg

• 90 mmHg

• 40 mmHg

• 25 mmHg

• 98 mmHg

Which of the following terms best describes the condition that results from having an increase in plasma bicarbonate concentrations?

• Respiratory alkalosis
• Metabolic acidosis
• Metabolic alkalosis
• Respiratory acidosis

Answer explanation

Metabolic alkalosis is best described as a condition resulting from an increase in plasma bicarbonate concentrations. It relates to the metabolic aspect of bodily functions, denoting an imbalance in the body's acid-base, specifically a deficiency of acid or a overabundance in bases, such as bicarbonate.

Classify the patient's acid-base disorder based on the lab values provided.

ABG: 7.22 / 55 / 75 / 35 / 94%

• Respiratory acidosis

• Normal acid-base balance
• Respiratory alkalosis

• Metabolic acidosis

• Metabolic alkalosis

Answer explanation

ABG: 7.22 / 55 / 75 / 35 / 94%

pH 7.22 is low (acidic = acidosis)

pCO2 55 is high

Since pH low and pCO2 is high = Respiratory acidosis