Lab 27: Analysis of a simulated urine sample



Lab 27: Analysis of a simulated urine sample

General:

• The lab report should be written in 3rd person. No “I” or “we” should be used.

• The lab report should contain the sections that are listed below and are denoted in BOLD. Each section should be clearly labeled and separated in the report.

introduction

Must include background information about the kidney and composition of urine.

• What is the normal composition of the urine produced by the human kidney?

• What substances are filtered, reabsorbed and secreted by the kidney?

• What is the kidney’s role in maintaining the normal electrolyte and osmotic balance among the cells, intercellular fluid and the blood?

• How do the hormones, aldosterone and antidiuretic hormone, affect the content of urine?

• What is the role of the kidney in the maintenance of normal blood pressure?

• Why is urine routinely tested?

• What information can a doctor obtain from testing a patient’s urine?

for each of the five problems you should state the problem, hypothesis, materials and methods, results and discussion in a separate section for each.

PROBLEM 1:

How can the relative concentration of glucose in an unknown urine sample be determined?

hypothesis: The concentration of urine in the unknown sample should correspond to a standard glucose concentration.

Materials and Methods: Describe what you did in the past tense like you are telling a story.

Results: Describe your results in words. Refer to the appropriate table which is on your lab sheets.

Discussion:

• How were you able to determine the concentration of the unknown urine sample?

• How would you make a 5% solution of glucose from a 20% glucose solution using the serial dilution technique?

• What is the difference between a quantitative test and a qualitative test?

• Why is this test considered semi-quantitative?

• Why would a doctor need to know if his/her patient’s urine contained glucose?

• Discuss two errors that may have affected your results.

problem 2:

How can we determine the specific gravity of urine?

Hypothesis: If the specific gravity of urine is___________ then the urine contains______________.

Materials and Methods: Follow above instructions for material and methods.

Results: Follow above instructions for results.

Discussion:

• What does specific gravity indicate about urine?

• What does a low specific gravity indicate about the health of an individual? Be specific. (hint: diabetes insipidus)

• Explain why seawater has a higher specific gravity than fresh water.

problem 3:

How can the pH of urine be determined?

Hypothesis: If urine contains a high concentration of H+ then it will be acidic.

Materials and Methods: Follow previous instructions

Results: Follow previous instructions

Discussion:

• What is the normal pH range for urine?

• How can diet affect the pH of urine?

• How can pH help a physician diagnose kidney disease?

Problem 4:

How can we determine the presence of chloride ions in urine?

Hypothesis: If urine contains chloride ions, then ___________________

Materials and Methods: Follow above instructions for materials and methods

Results: Follow above instructions for results.

Discussion:

• What information can a doctor obtain by knowing the chloride ion concentration in a patient’s urine?

• A doctor put his/her patient on a low salt (sodium) diet. Why would this doctor order a urine test that measured the sodium concentration of the patient’s urine?

Problem 5:

How can we determine if urea is present in our unknown urine sample?

Hypothesis: If _____________________, then __________________.

Materials and Methods: Follow above instructions for this section.

Results: Follow above instructions for this section

Discussion:

• Many bacteria in the environment produce urease. How is this fact related to the characteristic odor in horse barns and unintended cat litter boxes?

• An animal urinates on a plant. How does the animal’s urine contribute to the nitrogen cycle? Be sure to include bacteria and urease in your answer.

Finally, staple your completed lab sheets to your report. You do not need to answer the discussion questions because they are included in the discussion questions given above. Make sure you include citations in your introduction section. Follow APA format.

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