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Free STEP1 Exam Braindumps (page: 56)

Page 55 of 213
PDF with 845 Questions

The eye examination of a patient with diabetes mellitus reveals no cataract or glaucoma. The patient's ophthalmoscopic picture of his left eye is shown in the below figure. Which of the following is most likely affected?

  1. color vision
  2. high acuity vision
  3. near point vision
  4. scotopic vision
  5. spatial vision

Answer(s): D

Explanation:

The picture, representing the back of the retina as seen through the ophthalmoscope, shows a normal optic disk, a normal macula lutea, and no obvious neovascularization. On the other hand, there are dot hemorrhages as well as one flame-shape hemorrhage site present in the peripheral retina. This indicates an early stage of diabetic retinopathy, known as background retinopathy, in which microaneurysms occur due to damage of existing blood vessels. Since the damage occurred in the peripheral retina, rod vision, also called scotopic vision, is affected. There is no obvious damage yet in the macula lutea and the fovea centralis. At these places, cones are found in the greatest number. Since cones are responsible for color vision, choice Ais incorrect. Since the fovea centralis is the place for high acuity vision, choice B is incorrect. Changes in near point vision (choice C) indicate an error in the refractive power of the eye which is associated with abnormalities at the cornea, the lens, or the geometry of the eyeball. Spatial vision (choice E) refers to the ability to discriminate between spatially defined features. It is mainly determined by visual neuronal networks that enhance visual acuity and contrast, which are both associated with photopic vision.



You are the primary care physician for a young female college student. She has been engaged over the past 3 months in a vigorous aerobic exercise training regime that includes a significant amount of running in a hot environment. You measure her hematocrit as part of a general physical examination. Her hematocrit could well be abnormal even though she is not anemic. Which of the following choices best fits this profile?

  1. Option A
  2. Option B
  3. Option C
  4. Option D
  5. Option E

Answer(s): E

Explanation:

The central points of this question concern the definitions of hematocrit and anemia. Hematocrit is the proportion of blood that is packed cells. The hematocrit reading will be decreased by anything that lowers the number of cells, as well as by anything that increases the volume of plasma. Anemia refers to a condition in which the total circulating erythrocyte mass has decreased. In this student, a long-term regime of exercise in a warm environment has chronically increased her plasma volume, hence her hematocrit is low. However, since her total red blood cell mass is normal, there is no anemia. Choice E is correct. It is common to see a chronic increase in plasma volume develop in response to long-term exercise in a warm environment. Exercising in a warm environment places demands on the circulatory system, which must perfuse working muscles as well as skin capillary beds (to facilitate heat loss). In addition, volume is lost to sweating. Increased plasma volume helps the body meet these demands. In choice A, hematocrit could be low if erythrocyte mass decreased more than blood volume. However, this profile does not fit the question because this individual would be anemic, since erythrocyte mass is low. Choice B could not be correct since decreased plasma volume and increased red cell mass cause increased hematocrit. In choice C, the patient would not be anemic and hematocrit would be increased. However, this is not the best response since, as described above, in an individual exercising in a warm environment the hematocrit is often decreased and plasma volume is usually increased. In choice D, hematocrit would have to be increased.



A 66-year-old male presents with angina and dyspnea on exertion. Auscultation of the chest reveals a loud systolic murmur. He is diagnosed with aortic valvular sclerosis. This stenosis of the aortic valve will cause a murmur that can be heard loudest at which interval shown in below figure?

  1. between A and B
  2. between B and C
  3. between C and D
  4. between D and A
  5. between D and B

Answer(s): C

Explanation:

Blood passes through the aortic valve, starting when the aortic valve opens at point C until it closes at point F. Hence aortic valve stenosis will cause turbulent blood flow (murmur) between C and D. Between Aand B (choice A) is the interval of diastolic filling when the aortic valve is closed. Between B and C is the period of isovolumetric contraction (choice B) before the aortic valve opens. Between D and Ais the period of isovolumetric relaxation (choice D) after the aortic valve closes. Between D and B the aortic valve is also closed.



Apatient is found to be deficient in folate. This patient is anemic, and a complete blood count indicates that the MCV is 105 fL (normal range: 8096) and the MCHC is 34 g/dL (normal range: 3236). The anemia is thus macrocytic, normochromic. In this patient how would you predict that the MCH (mean corpuscular hemoglobin) would compare with the normal range?

  1. MCH would be elevated with respect to the normal range
  2. MCH would be depressed with respect to the normal range
  3. MCH would be within the normal range
  4. this cannot be determined based on the information provided

Answer(s): A

Explanation:

These red blood cells are large (macrocytic) but have a normal hemoglobin concentration (normal MCH).
Since MCH is mean hemoglobin content per red cell, this value must be elevated since the cells are large and the concentration in the cell is normal. Choice A excludes choices BD.






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