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MSN 570 Advanced Pathophysiology Final 2024
1. The early stages of atheroma development are characterized by:
- A. macrophages full of oxidized low-density lipoprotein (LDL; i.e., foam cells) in the intima
- B. accumulation of lipids in the intima (i.e., fatty streak)
- C. accumulation of proteins such as collagen and elastin (i.e., fibrous cap)
- D. development of calcium and a necrotic lipid core
Correct answer: A
Rationale: The correct answer is A. In the early stages of atheroma development, macrophages accumulate oxidized low-density lipoprotein (LDL) and transform into foam cells, leading to the formation of fatty streaks in the intima of blood vessels. This process is a hallmark of the initial stages of atherosclerosis. Choice B is incorrect as it describes the accumulation of lipids in the intima, which is a later event following foam cell formation. Choice C is also incorrect as it refers to the accumulation of proteins forming the fibrous cap, which occurs at a later stage to stabilize the atheroma. Choice D is incorrect as it describes the development of calcium and a necrotic lipid core, typically seen in advanced atherosclerosis rather than the early stages.
2. Which of the following is a common cause of mechanical small intestine obstruction?
- A. Infection
- B. Postoperative adhesions
- C. Tumors
- D. Foreign body
Correct answer: B
Rationale: Postoperative adhesions are a common cause of mechanical small intestine obstruction. Adhesions can form after abdominal surgery, causing bands of scar tissue that may twist or pull the intestines, leading to obstruction. This is a more common cause compared to infection, tumors, or foreign bodies. Infection may lead to inflammation but is not a typical cause of mechanical obstruction. Tumors and foreign bodies can cause blockages but are less common than postoperative adhesions.
3. Which of the following is a characteristic of osteosarcoma?
- A. Slow-growing tumor that begins in the bone marrow
- B. Solitary tumor that most often affects the metaphyseal region of the femur or tibia
- C. An aggressive tumor most often found in the bone marrow of long bones
- D. A tumor that infiltrates the trabeculae in spongy bone and implants in surrounding tissue
Correct answer: C
Rationale: Osteosarcoma is an aggressive bone tumor that most commonly arises in the bone marrow of long bones, such as the femur or tibia. Choice A is incorrect as osteosarcoma is not a slow-growing tumor but rather a fast-growing one. Choice B is incorrect as osteosarcoma is not typically solitary but can involve multiple lesions. Choice D is incorrect as osteosarcoma primarily affects the medullary (marrow) cavity of bones, rather than infiltrating the trabeculae in spongy bone and surrounding tissue.
4. A 65-year-old man is admitted to the intensive care unit from the operating room after a triple coronary artery bypass graft. He is intubated and on a ventilator. Lactic acid levels were normal postoperatively, but now they are rising. The increased level could be an indication of:
- A. excessive sedation
- B. bowel ischemia
- C. excessive volume infusion in the operating room
- D. mild hypothermia postoperatively
Correct answer: B
Rationale: In this scenario, the rising lactic acid levels in a 65-year-old man after a coronary artery bypass graft could indicate bowel ischemia. Bowel ischemia can lead to anaerobic metabolism, causing an increase in lactic acid levels. Excessive sedation may cause respiratory depression but would not directly lead to rising lactic acid levels. Excessive volume infusion in the operating room might cause fluid overload but would not typically result in rising lactic acid levels. Mild hypothermia postoperatively could lead to shivering and increased oxygen consumption, but it is less likely to be the primary cause of rising lactic acid levels in this context.
5. Why does multiple sclerosis manifest as asymmetrical and in different parts of the body?
- A. Autoreactive lymphocytes are causing diffuse patchy damage to the myelin sheath in the central nervous system.
- B. Acetylcholine receptors are destroyed by immunoglobulin G.
- C. Autoreactive T lymphocytes cause progressive loss of neurons in the substantia nigra.
- D. Cortical motor cells degenerate.
Correct answer: C
Rationale: Multiple sclerosis is characterized by the immune system mistakenly attacking the myelin sheath in the central nervous system. This results in the formation of lesions that can occur in different parts of the central nervous system, leading to varied symptoms depending on the location of the damage. Choice A is the correct answer because it accurately describes the pathophysiology of multiple sclerosis. Choices B, C, and D are incorrect because they describe mechanisms or locations that are not associated with the pathogenesis of multiple sclerosis.
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