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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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Macular degeneration occurs as a result of:
- A. loss of lens accommodation
- B. detachment of the retina
- C. increased intraocular pressure
- D. impaired blood supply leading to cellular waste accumulation and ischemia
Correct Answer: D
Rationale: Macular degeneration is a condition that affects the macula, a part of the retina responsible for central vision. It is primarily caused by impaired blood supply to the macula, leading to cellular waste accumulation and ischemia. This results in the death of photoreceptor cells and ultimately vision loss. Choices A, B, and C are incorrect because macular degeneration is not related to the loss of lens accommodation, detachment of the retina, or increased intraocular pressure. The correct answer directly addresses the underlying pathophysiology of macular degeneration.
After a 27-year-old woman with epilepsy had a generalized seizure, she feels tired and falls asleep. This is:
- A. an ominous sign.
- B. normal and termed the postictal period.
- C. a reflection of an underlying brain tumor.
- D. only worrisome if there are focal neurologic deficits after.
Correct Answer: B
Rationale: The correct answer is B: normal and termed the postictal period. The postictal period is a common phase following a seizure where the individual may experience fatigue, confusion, or sleepiness. It is a normal part of the seizure event and does not necessarily indicate a serious issue. Choice A is incorrect because feeling tired and falling asleep after a seizure is not an ominous sign but rather a typical postictal symptom. Choice C is incorrect as there is no indication in the scenario provided that links the symptoms to an underlying brain tumor. Choice D is incorrect because the absence of focal neurologic deficits does not make the postictal period worrisome.
A 70-year-old woman has difficulty with driving, and she has been frequently getting lost. Her husband said she has also been acting strange and seems to want to sleep a lot. He said the other night she kept saying she was seeing animals such as lions in her room. He says her memory is not too bad, but he is very concerned about her health. Physical examination reveals an alert woman with stable vital signs. Bradykinesia and limb rigidity are noted. These findings are consistent with:
- A. Alzheimer's disease.
- B. Vascular dementia.
- C. Dementia with Lewy bodies.
- D. Frontotemporal dementia.
Correct Answer: C
Rationale: The symptoms described in the scenario, such as visual hallucinations, fluctuations in cognition, and parkinsonism (bradykinesia and limb rigidity), are classic features of dementia with Lewy bodies (DLB). DLB is characterized by the presence of Lewy bodies in the brain, which are abnormal protein deposits. Alzheimer's disease (Choice A) typically presents with memory loss as a predominant symptom, which is not a major concern in this case. Vascular dementia (Choice B) is associated with a history of cerebrovascular disease and is not supported by the symptoms described. Frontotemporal dementia (Choice D) usually presents with changes in behavior and personality, rather than the symptoms described in the scenario.
A 30-year-old has poorly controlled asthma and is taking prednisone 10 mg by mouth once a day. He has been on this regimen for 6 weeks. Abrupt withdrawal or discontinuation of this medication can cause:
- A. adrenal crisis
- B. hypercortisolism
- C. ACTH stimulation
- D. thyroid crisis
Correct Answer: A
Rationale: Abrupt withdrawal or discontinuation of prednisone, a corticosteroid, can lead to adrenal crisis. This occurs due to the suppression of the adrenal glands' natural cortisol production caused by prolonged exogenous steroid administration. Adrenal crisis presents with symptoms such as weakness, fatigue, abdominal pain, and hypotension. Hypercortisolism (Cushing syndrome) results from chronic excessive exposure to cortisol, not abrupt withdrawal. ACTH stimulation would be expected in response to low cortisol levels, not as a direct consequence of prednisone withdrawal. Thyroid crisis (thyroid storm) is associated with severe hyperthyroidism and is not directly related to corticosteroid withdrawal.
Which of the following cell types would be the first to aid in killing bacteria to prevent infection in his hand?
- A. Eosinophils
- B. Neutrophils
- C. Leukotrienes
- D. Monocytes
Correct Answer: B
Rationale: Neutrophils are the first responders to a bacterial infection. They are phagocytes that engulf and destroy bacteria, playing a crucial role in the early stages of the immune response. Eosinophils are primarily involved in combating parasitic infections and allergic reactions, not bacterial infections. Leukotrienes are signaling molecules that contribute to inflammation and immune responses, but they are not cells. Monocytes are another type of white blood cell that differentiates into macrophages and dendritic cells, playing a role in immune response but not as immediate as neutrophils.