Assignment task:
Scenario 1:
Presentation: 65-year-old woman with a loss of appetite, abdominal cramps, constipation, and blood in her stool.
History: Delores Murphy, a 65-year-old white female, was in good health until about 6 weeks ago, when she noted occasional cramps in the left lower quadrant of the abdomen associated with constipation. The episodes of cramping last about 30 minutes each and are most severe in the hour following her meals. She has taken laxatives which have partially relieved her symptoms, but she has had a decreased appetite and 12-pound weight loss over the past four weeks. In addition, she has become increasingly fatigued over this period. When questioned about her bowel habits, she reported bright red blood in her stools and a smaller caliber (i.e., diameter) of stool over the past two weeks.
Physical Examination: She appeared fatigued and distressed. Head and neck exams were normal, as was her thorax. Palpation of the abdomen revealed a 10 x 10 cm mass and tenderness in the left lower quadrant. Percussion over this area revealed a hollow, tympanic sound. Hepatomegaly was noted, and a hard and slightly tender liver edge was felt in the right upper quadrant. Bowel sounds were noticeably reduced. A stool sample was tested with Guaiac paper and was positive for blood.
Questions: Choose one of the three sets of questions to serve as your initial response.
1. Propose an explanation for Delores's abdominal cramps and left lower quadrant mass.
2. Propose an explanation for Delores's reduced bowel sounds and smaller-caliber stools.
3. What is "flexible sigmoidoscopy"?
OR
1. How is an "air-contrast barium enema" performed?
2. Propose an explanation for Delores's weight loss and decreased appetite.
3. How would the appearance of an adenoma differ from that of a carcinoma under the microscope?
OR
1. Why was it important to biopsy suspicious lesions?
2. What kinds of information can be gained by performing an air-contrast barium enema?
3. Ninety percent of all cancers are carcinomas. Propose an explanation for why such a disproportionately high number of cancers are carcinomas.
Scenario 2:
Presentation: A 14-year-old girl with cystic fibrosis has complained of an increased cough productive of green sputum over the last week. She also complained of being increasingly short of breath, and she is noticeably wheezing on physical examination.
Arterial blood was drawn and sampled, revealing the following values:
| pH |
7.3 |
| pCO2 |
50 mm Hg |
| pO2 |
55 mm Hg |
| Hemoglobin - O2 saturation |
45 % |
| [HCO3-] |
24 meq / liter |
Normal Levels of Substances in the Arterial Blood:
| pH |
7.40 + 0.05 |
| pCO2 (partial pressure of carbon dioxide) |
40 mm Hg |
| pO2 (partial pressure of oxygen) |
90 - 100 mm Hg |
| Hemoglobin - O2 saturation |
94 - 100 % |
| [HCO3-] |
24 meq / liter |
Questions: Choose one of the two sets of questions to serve as your initial response:
1. What causes cystic fibrosis? Describe the pathophysiologic mechanisms of the disease.
2. How would you classify this girl's acid-base status?
3. How does cystic fibrosis cause this acid-base imbalance?
OR
1. How would the kidneys try to compensate for the girl's acid-base imbalance?
2. This girl has also had a long history of diarrhea and poor weight gain. Explain why.
3. List some other causes of this type of acid-base disturbance.