Nokea
Which of the following moves furthest to the anode on cellulose acetate electrophoresis of normal haemoglobin at pH 8.6?
- A. Haemoglobin A
- B. Haemoglobin D
- C. Haemoglobin A2
- D. Haemoglobin S
Correct Answer: A
Rationale: The correct answer is A: Haemoglobin A. In cellulose acetate electrophoresis at pH 8.6, haemoglobin A moves furthest towards the anode because it has the highest net negative charge among the normal haemoglobins. This is due to the high number of negatively charged amino acids in haemoglobin A compared to the other normal haemoglobins. Haemoglobin D, A2, and S have different amino acid sequences and charge distributions, resulting in them migrating at different rates. Haemoglobin D and A2 are minor components with lower net negative charge compared to A. Haemoglobin S, on the other hand, has a different charge distribution due to the substitution of glutamic acid with valine in the beta chain, causing it to migrate differently than haemoglobin A.
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A patient is scheduled for upcoming surgery. He is on nonsteroidal anti-inflammatory drugs (NSAIDs) for rheumatoid arthritis. You are being asked what to do with his medications for the surgery. What is the mechanism of action of NSAIDS?
- A. Irreversible inhibition of cyclooxygenase 1
- B. Irreversible inhibition of cyclooxygenase 2
- C. Reversible inhibition of cyclooxygenase 1
- D. Reversible inhibition of cyclooxygenase 2
Correct Answer: C
Rationale: Step 1: NSAIDs inhibit cyclooxygenase (COX) enzymes to reduce prostaglandin synthesis.
Step 2: Reversible inhibition means the effect is temporary and can be reversed.
Step 3: COX-1 inhibition leads to GI side effects, which can be concerning in surgery.
Step 4: COX-2 inhibition is more targeted for inflammation but can still pose cardiovascular risks.
Step 5: Reversible COX-1 inhibition allows for temporary discontinuation before surgery to minimize bleeding risk.
Summary: Choice C is correct as reversible COX-1 inhibition allows for safer management pre-surgery compared to irreversible inhibition in choices A and B, and COX-2 inhibition in choice D.
The nurse is reviewing the activated partial thromboplastin time for a patient receiving heparin. Which value indicates that the medication is within the therapeutic range?
- A. 2.5 to 9.5 minutes
- B. 9.5 to 11.3 seconds
- C. 1.5 to 2.0 times normal
- D. 2.0 to 3.0 times normal
Correct Answer: C
Rationale: The correct answer is C (1.5 to 2.0 times normal) because the therapeutic range for heparin is typically considered to be 1.5 to 2.5 times the normal value of activated partial thromboplastin time (aPTT). This range ensures adequate anticoagulation without increasing the risk of bleeding. Options A, B, and D are incorrect because they do not accurately reflect the therapeutic range for heparin. Option A provides a range in minutes, which is not a standard unit for aPTT measurement. Option B provides a range in seconds, which is too narrow for the therapeutic range of heparin. Option D provides a range in multiples of normal, but the upper limit of 3.0 times normal is higher than the typical upper limit of the therapeutic range for heparin.
A patient with abdominal injuries from a motor vehicle crash is scheduled for surgery to remove the spleen. What bodily function will be affected by the removal of this organ?
- A. Filtration of waste products
- B. Removal of old red blood cells from circulation
- C. Clearance of mucous in the tracheobronchial tree
- D. Facilitation of glucose to be used by the cell for energy
Correct Answer: B
Rationale: The correct answer is B: Removal of old red blood cells from circulation. The spleen is responsible for filtering and removing old or damaged red blood cells from the bloodstream. When the spleen is removed, this function is compromised, leading to a decreased ability to clear out old red blood cells. This can result in an increased risk of anemia and other complications related to the breakdown of red blood cells.
Choices A, C, and D are incorrect:
A: Filtration of waste products - The spleen primarily filters blood cells, not waste products.
C: Clearance of mucous in the tracheobronchial tree - This function is mainly carried out by the respiratory system, not the spleen.
D: Facilitation of glucose to be used by the cell for energy - This is a function of the pancreas and insulin, not the spleen.
In iron deficiency anemia there is characteristically
- A. An atrophic gastritis
- B. A low mean corpuscular volume
- C. A reduced total iron binding capacity
- D. Megaloblastic changes in the bone marrow
Correct Answer: B
Rationale: The correct answer is B: A low mean corpuscular volume. In iron deficiency anemia, there is a decreased amount of iron available for hemoglobin synthesis, leading to smaller and paler red blood cells. This results in a low mean corpuscular volume (MCV). Atrophic gastritis (choice A) is associated with vitamin B12 deficiency anemia, not iron deficiency anemia. Choice C (reduced total iron binding capacity) is incorrect because in iron deficiency anemia, there is an increased total iron binding capacity due to the body's attempt to capture more iron. Megaloblastic changes in the bone marrow (choice D) are seen in megaloblastic anemia, not iron deficiency anemia.
A 14-year-old boy presents with cough, shortness of breath, and difficulty lying down. His face and neck swell when his arms are raised. Chest x-ray reveals a large mediastinal mass. A tissue diagnosis is desired. A biopsy is performed with local anesthesia because the anesthesiologist thinks that the patient has a very high general anesthesia risk. Which of the following findings does not make general anesthesia unsafe?
- A. Tumor diameter greater than 45% of transthoracic diameter
- B. Tracheal cross-sectional area less than 50% of predicted
- C. Peak expiratory flow rate less than 50% of predicted
- D. A malignancy of hematopoietic origin
Correct Answer: D
Rationale: The correct answer is D. A malignancy of hematopoietic origin does not inherently make general anesthesia unsafe. This is because anesthesia risk is typically influenced by factors such as airway patency, respiratory function, and cardiac status. Choices A, B, and C all indicate potential complications that could make general anesthesia unsafe, such as airway obstruction due to a large mediastinal mass (A), compromised tracheal cross-sectional area (B), and impaired respiratory function (C). These factors would necessitate careful consideration and potential modifications in the anesthesia plan to ensure patient safety.