@marimphil wrote:
typing over the past month. She also notes that her hands begin to feel
numb and weak after typing for long periods of time. Upon testing, which
of the following deficits would be predicted?
Anwser
2>The smooth part of the right atrium derives from which of the following
embryonic structures?
Anwser
3>A 66-year-old male presents with chronic fatigue. On examination, the
patient is noted to have lymphadenopathy and an enlarged liver and spleen.
Laboratory examination reveals a white blood cell count of 25,000/mL with
93% lymphocytes; the lymphocytes appear small and mature. Both the
Anwser
4>A patient who has suffered severe chest trauma in an automobile accident
is found to have fluid in the right pleural space. A thoracentesis reveals
the presence of chylous fluid in the pleural space, suggesting a rupture
of the thoracic duct. In which regions of the thorax is the thoracic
Anwser
5>A 15-year-old boy is evaluated by a clinician for failure to develop norma
l male secondary sexual characteristics. Physical examination reveals small
testes, a small penis, and gynecomastia. The boy has had some difficulties
in school, and the parents say that the school psychometrist said he had
an IQ of 90. This patient's condition is most likely to be related to
Anwser
6>Careful testing of the visual fields in a patient complaining of difficulty
reading demonstrates a central scotoma involving one visual field. This
defect is most likely due to a lesion involving which of the following
structures?
Anwser
7>A 70-year-old woman with a history of multiple small strokes reports to her
physician that she has had multiple recent experiences that something or
someone seemed very familiar, when in reality they were not familiar to
her. This type of experience is called which of the following?
Anwser
8>A 33-year-old single mother of two young children visits her physician
because of an oral ulcer. A review of systems is significant for fatigue,
myalgia, and joint pain. Laboratory results demonstrate leukopenia, and
a high-titered antinuclear antibody. A speckled staining pattern due
to anti-Sm is seen with immunofluorescence; urinary protein is elevated.
Anwser
9>Researchers are assessing the specificity of a screening procedure for
breast cancer in a population of 3000 women whose mothers had the disease.
The presence or absence of a malignant condition is established by
conventional mammography, which is assumed to be definitive for the
Cancer 90 10 100
No cancer 360 2540 2900
Total 450 2550 3000
What is the specificity of the test?
Anwser
10>A patient develops fever, shortness of breath, and appears to be quite
ill. X-ray demonstrates bilateral interstitial lung infiltrates.
Bronchial washings demonstrate small "hat-shape" organisms visible
on silver stain within alveoli. Which predisposing condition is most
likely to be present in this patient?
Anwser
11>A 35-year-old retarded man with a strong history of mental retardation
among male relatives undergoes genetic testing. His lymphocytes are
cultured in a medium containing methotrexate and 4% of the metaphase
chromosomes in the lymphocytes show a breakpoint at q27.3 on the X
Anwser
12>While lying supine in bed eating, a child aspirates a peanut. Which of
the following bronchopulmonary segments would this foreign object mos
t likely enter?
Anwser
13>A 43-year-old man is brought to the general medicine clinic by his wife.
She states that his memory has progressively deteriorated over the last
several years, and that his personality has been changing. On examination,
the physician notes abnormal, writhing movements of the man's limbs and
Anwser
14>During a routine physical examination of a 74-year-old man, a physician
palpates a large, pulsating mass in the lower abdomen. To which of the
following is this mass most likely etiologically related?
Anwser
15>The cell in the center of the electron micrograph above is important in
wound healing and plays a role in the pathological process underlying
Dupuytren's contracture. Which of the following cell types is
depicted?
Anwser
16>Damage to which of the following structures might produce hair cell loss?
Anwser
17>A thyroid mass usually moves with swallowing because the thyroid gland
is enclosed by which of the following fascia?
Anwser
18>The blood from an 8-year-old boy was analyzed by flow cytometry
. The exact number of B cells was counted. Which of the following
cell surface markers was likely used to identify the B cells in
this blood sample?
Anwser
19>A child who has had abnormal development of the membranous bones has
a broad skull with associated facial and dental anomalies. Which
other bones are most likely to also be affected?
Anwser
20>Which of the following drugs used in the treatment of noninsulin-dependent
diabetes mellitus (NIDDM) has no effect on the secretion of insulin?
Anwser
21>A 57-year-old man presents with a steady, severe pain in the right
hypochondrium, nausea, vomiting, and a temperature of 102 F. He states
that his signs and symptoms began shortly after eating his favorite
pizza with extra cheese, pepperoni, and sausage. Laboratory examination
Anwser
22>After falling on his laterally outstretched arm, a patient suffered a
dislocation of the glenohumeral joint. Which of the following nerves
is most likely to have been injured from this dislocation?
Anwser
23>A 45-year-old woman presents to her physician because of a severe "sore
throat." Physical examination demonstrates fever and an extremely tender,
enlarged thyroid gland, but no throat erythema. Serum thyroid studies
demonstrate a mild degree of hyperthyroidism. Two months later,
the patient is asymptomatic, and thyroid function tests have
Anwser
25>A patient has an insulin-secreting tumor that is localized to the tail of
the pancreas. Which of the following would most likely be an associated
finding during fasting?
Anwser
26>A 14-year-old girl with a high fever and sore throat presents to the
emergency room. A complete blood count with differential implies the
presence of a viral infection. Which of the following best describe
s the cells that indicate a viral etiology to her illness?
Anwser
27>A 35-year-old woman notices a change in the appearance of a mole on her
neck. Physical examination reveals that the lesion is an irregular,
nodular, superficial mass with a variegated appearance. Biopsy
demonstrates a primary malignant tumor. Which of the following
Anwser
28>A patient develops a swollen and tender lymph node in his popliteal fossa.
An infected skin lesion in which of the following sites would most likely
induce lymphadenopathy in this region?
Anwser
29>A 4-year-old child living in a slum is bitten by a rat while sleeping. Two
days later, the child develops a rash characterized by discrete
erythematous 1-4 mm macules on the extremities and face, most obvious
on the palms and soles. Which of the following organisms is the most
likely cause of this child's disease?
Anwser
30>A 25-year-old woman develops extensive pruritic wheals following
ingestion of seafood to which she was allergic. While these lesions
are usually not biopsied, a biopsy would probably show which of the
following features?
Anwser
31>A 43-year-old man presents complaining of pain in the groin. On examination,
his physician palpates a bulge in the region of the superficial inguinal
ring, which he diagnoses as a direct inguinal hernia. The hernial sac
most likely
Anwser
32>A 60-year-old alcoholic smoker abruptly develops high fever, shakes,
a severe headache, and muscle pain. He initially has a dry, insignificant
cough, but over the next few days he develops marked shortness of breath
requiring assisted ventilation. Chest x-ray demonstrates homogeneous
radiographic shadowing that initially involves the left lower lobe
but continues to spread until both lungs are extensively involved.
Culture of bronchoalveolar lavage fluid on buffered charcoal yeast
extract (BCYE) demonstrates a coccobacillary pathogen. Which of the
following is the most likely causative organism?
Answer
33>An experimental serologic test is developed to detect the presence of
HIV antibody. Epidemiological analysis reveals the results shown
below.
Positive test 100 50
Negative test 20 950
What is the sensitivity of this test?
Anwser
34>A 30-year-old pregnant woman of Jewish descent presents to a physician
with painful oral ulcers. Physical examination demonstrates widespread
erosions of her mucous membranes. Close examination reveals a friable
mucosa, but no well-defined aphthous ulcers. Biopsy of perilesional
Anwser
35>A 40-year-old woman presents to the emergency department because of
hematuria. Laboratory analyses show significant proteinuria, bacteria
and white cells in the urine, and a blood urea nitrogen (BUN) of
40 mg/dL with a creatinine of 4.0 mg/dL. Ultrasonography reveals
enlarged kidneys, and she is given a provisional diagnosis of
Anwser
36>During development, the formation of the kidney is induced by which of
the following structures?
Anwser
37>A premature infant develops progressive difficulty breathing over the first
few days of life. Deficient surfactant synthesis by which of the following
cell types may have contributed to the baby's respiratory problems?
Anwser
38>A surgeon performs an exploratory laparotomy, producing a large incision in
the patient's abdomen. Poor blood supply to which of the following is most
likely to cause problems during the healing process?
Anwser
39>Which of the following would be expected to be decreased in a patient with
chronic hypertension secondary to renal artery stenosis?
Anwser
40>A patient, who appears to be female, is found to be 46,XY. The patient's
vagina is very shallow, ending in a blind pouch, and there are palpable
masses in the labia. The diagnosis of testicular feminization syndrome
is made. Which of the following was most likely present during the early
Anwser
41>A healthy 42-year-old woman with a history of anxiety attacks sits in the
hospital waiting room as her 3-year-old daughter undergoes open heart
surgery for a septal malformation. The woman experiences a feeling of
suffocation and is obviously hyperventilating. She informs her husband
Anwser
42>Which of the following occurs at the darkly stained band indicated by the
arrow?
Anwser
43>A 38-year-old AIDS patient presents to his physician's office in Kansas
City, Missouri, complaining of fever for the past week and an increasing
headache. He also states that sunlight hurts his eyes and that he has
been feeling nauseated and weak. His past medical history is significant
for Pneumocystis pneumonia and a total CD4 count of 89. Current
medications are trimethoprim/sulfa and indinavir. Cerebrospinal
Anwser
44>To which of the following diseases is pyruvate kinase deficiency most
similar clinically?
Anwser
45>A 60-year-old male with angina comes to the emergency room with severe
chest pain unresponsive to sublingual nitroglycerin. An EKG shows ST
segment elevation in the anterolateral leads, and thrombolytic therapy
is initiated. If streptokinase is given to this patient, it may produce
thrombolysis after binding to which of the following proteins?
Anwser
46>A child is brought to the pediatrician because of perianal itching, which
has been disturbing the child's sleep. Physical examination reveals scaly
skin in the perianal region. The physician instructs the parents to place
transparent tape on the perianal region the next morning, and then retur
n to the office. In the office, the tape is transferred to a microscope
Anwser
47>A healthy, 37-year-old, recently divorced woman loses her job at the auto
factory. She picks up her three young children from the factory day care
center and gets into an automobile accident on the way home. Her
5-year-old son, who was not wearing a seat belt, sustains a severe
Anwser
48>A 66-year-old man with urinary retention secondary to prostatic hyperplasia
develops a spiking fever and tachypnea. Physical exam reveals intercostal
muscle retractions and bilateral inspiratory crackles. A chest x-ray
exhibits bilateral interstitial and alveolar infiltrates. Arterial blood
gases demonstrate severe hypoxemia. Blood cultures would most likely
Anwser
49>A patient arrives in the emergency room after having attempted suicide by
lacerating his wrist. No major artery was damaged, but the nerve that is
immediately lateral to the flexor digitorum superficialis tendon is cut.
Which of the following actions will no longer be possible?
Anwser
50>A 48-year-old female is being treated for breast carcinoma. Over the past
few days, she has been complaining of dysuria and frequency. Laboratory
examination revealed the presence of microscopic hematuria. The next day
the patient developed gross hematuria. Which of the following agents
most likely caused the development of these signs and symptoms?
Anwser
Answers
1>The correct answer is C. This is a classic presentation of a
patient with carpal tunnel syndrome, which typically affects females
between the ages of 40 and 60 who chronically perform repetitive tasks
that involve movement of the structures that pass through the carpal
tunnel. One important structure that passes through the carpal tunnel is
the median nerve. Patients often note a tingling, a loss of sensation,
or diminished sensation in the digits. There is also often a loss of
coordination and strength in the thumb, because the median nerve also
sends fibers to the abductor pollicis brevis, flexor pollicis brevis,
and the opponens pollicis. A final function of the median nerve distal
to the carpal tunnel is control of the first and second lumbricals which
function to flex digits two and three at the metacarpophalangeal joints
and extend interphalangeal joints of the same digits.
Abduction of the fifth digit (choice A) is a function controlled by the
ulnar nerve, which does not pass through the carpal tunnel.
Adduction of the thumb (choice B) is a function of the adductor
pollicis, which is the only short thumb muscle that is not innervated by
the median nerve, but rather by the deep branch of the ulnar nerve.
Sensation of the lateral half of the dorsum of the hand (choice D) is
mediated by the radial nerve, which also does not pass through the
carpal tunnel.
Sensation over the lateral aspect of the palm (choice E) is mediated by
the median nerve, however the branch innervating the palm (palmar
cutaneous branch of the median nerve) passes superficial to the carpal
tunnel.
Sensation over the medial aspect of the dorsum of the hand (choice F) is mediated by the ulnar nerve.
Sensation over the medial aspect of the palm (choice G) is mediated by the ulnar nerve.
2> The correct answer is D. The smooth part of the right atrium (the
sinus venarum) is derived from the sinus venosus. The coronary sinus and
the oblique vein of the left atrium also derive from the sinus venosus.
The bulbus cordis (choice A) gives rise to the smooth part of the right
ventricle (conus arteriosus) and the smooth part of the left ventricle
(aortic vestibule).
The primitive atrium (choice B) gives rise to the trabeculated part of the right and left atria.
The primitive ventricle (choice C) gives rise to the trabeculated part of the right and left ventricles.
The truncus arteriosus (choice E) gives rise to the proximal part of the aorta and the proximal part of the pulmonary artery.
3>The correct answer is A. Chronic lymphocytic leukemia (CLL) is
typically a disease of the elderly, with 90% of cases occurring after
the age of 50; the median age is 65. Patients will typically present
with a complaint of chronic fatigue and/or lymphadenopathy.
Approximately 50% of all patients with CLL present with an enlarged
liver and/or spleen. CLL typically pursues an indolent course but can
occasionally present as a rapidly progressive disease. The hallmark of
CLL is the isolated lymphocytosis in which the white blood cell count is
usually greater than 20,000/mL and between 75% and 98% of the
circulating cells are small "mature" lymphocytes. Chlorambucil is
classified as a nitrogen mustard, a subcategory of the alkylating
agents. It is primarily used to treat chronic lymphocytic leukemia and
ovarian carcinoma; it can also be used to treat Hodgkin's disease and
various other lymphomas.
Cisplatin (choice B) is an alkylating agent indicated for the treatment
of metastatic testicular and ovarian tumors in combination with other
agents.
Dacarbazine (choice C) is a cytotoxic agent with alkylating properties.
It is used as a single agent or in combination with other
antineoplastics in the treatment of metastatic malignant melanoma,
refractory Hodgkin's disease, and various sarcomas.
Tamoxifen (choice D) is an antiestrogen hormone used in the palliative
treatment of breast cancer in patients with estrogen-receptor-positive
breast cancer.
Vinblastine (choice E) is a mitotic inhibitor antineoplastic agent
indicated for the treatment of Hodgkin's disease and non-Hodgkin's
lymphomas, choriocarcinoma, lymphosarcoma, and neuroblastoma, as well as
various other types of cancer.
4>The correct answer is E. The mediastinum is divided into four
regions. The region above the manubriosternal junction (level of fourth
thoracic vertebra) is the superior mediastinum. The region below the
manubriosternal junction is divided into the anterior mediastinum
(anterior to the pericardium), the middle mediastinum (within the
pericardium), and the posterior mediastinum (posterior to the
pericardium). The thoracic duct enters the thorax through the aortic
hiatus of the diaphragm. At this point it lies in the posterior
mediastinum, the region posterior to the pericardium. As it ascends
through the thorax and passes the level of the fourth thoracic vertebra,
it enters the superior mediastinum.
The anterior mediastinum (choices A and B) contains the thymus and fatty connective tissue.
The middle mediastinum (choices A, C, and D) contains the heart and the roots of the great vessels.
In addition to the thoracic duct, the superior mediastinum (choices B,
D, and E) contains the ascending aorta, aortic arch, branches of the
aortic arch, descending aorta, superior vena cava, brachiocephalic
veins, thymus, trachea and esophagus.
In addition to the thoracic duct, the posterior mediastinum (choices C
and E) contains the descending aorta, azygos vein, hemiazygos vein and
the esophagus
5The correct answer is C. The boy probably has Klinefelter's syndrome
(47, XXY), which has the typical presentation described in the question.
The condition arises as a result of failure of separation
(nondisjunction) of the sex chromosomes, and can be related to either
paternal nondisjunction (slightly more common) or maternal
nondisjunction.
Deletions (choice A) are a common form of genetic disease and contribute to many genetic recessive diseases.
Examples of nondisjunction of autosomes (choice B) include trisomies
such as most cases of Down's syndrome (trisomy 21), Edwards' syndrome
(trisomy 18), and Patau syndrome (trisomy 13).
There are two types of translocations: non-Robertsonian (choice D) and
Robertsonian (choice E). Non-Robertsonian (reciprocal) translocations
result when two non-homologous chromosomes exchange genetic material.
Robertsonian translocations are a special type of translocation that
involve exchange of genetic material from the long arms of one
acrocentric chromosome to the long arms of another acrocentric
chromosome, with fusion of the centromeres. Four percent of cases of
Down's syndrome are caused by this mechanism.
6>The correct answer is A. The probable location of lesions producing
visual defects is a favorite USMLE topic (and is also well worth
knowing if you have occasion to work up such a patient). Here is a list
that may help you sort through these problems:
Central scotoma ~ macula
Ipsilateral blindness ~ optic nerve
Bitemporal hemianopia ~ optic chiasm (choice B)
Homonymous hemianopia ~ optic tract (choice E)
Upper homonymous quadrantanopia ~ temporal optic radiations (choice D)
Lower homonymous quadrantanopia ~ parietal optic radiations (choice C)
Also, cortical lesions produce defects similar to those of the optic radiations, but may spare the macula.
--------------------------------------------------------------------------------7>The
correct answer is C. This is deja vu ("seen before"), which is the
experience of an event, person, or thing as familiar, even though it has
never previously been experienced. Severe cases often accompany an
underlying neurologic problem.
Anterograde amnesia (choice A) is the inability to learn new facts. Most
commonly, it involves both verbal and nonverbal material, but it can
involve one or the other.
In confabulation (choice B), a patient reports "memories" of events that did not take place at the time in question.
In jamais vu (choice D), a patient fails to recognize familiar events that have been encountered before.
In retrograde amnesia (choice E), a patient fails to remember facts or events that occurred before the onset of amnesia.
--------------------------------------------------------------------------------8>The
correct answer is E. Systemic lupus erythematosus (SLE) is a prototype
connective tissue disease. The diagnosis requires four criteria to be
met from a list of eleven possible criteria: malar rash, discoid rash,
photosensitivity, oral ulcers, arthritis, serositis, renal disorder,
neurologic disorder, hematologic disorder, immunologic disorder, and
antinuclear antibody. This patient also has anti-Sm, which is
pathognomonic for SLE, but is only found in 30% of the affected
patients. Antinuclear antibodies (ANA) are present in 95-100% of cases
of SLE; anti-double-stranded DNA is found in 70% of the cases.
Generalized fatigue (choice A) due to being a single working mother of
two children could well be a possibility, but the presence of the other
criteria make SLE more likely.
Goodpasture's syndrome (choice B) is characterized by linear disposition
of immunoglobulin, and often C3, along the glomerular basement membrane
(GBM). Glomerulonephritis, pulmonary hemorrhage, and occasionally
idiopathic pulmonary hemosiderosis occur.
Mixed connective tissue disease (choice C) is an overlap syndrome
characterized by a combination of clinical features similar to those of
SLE, scleroderma, polymyositis, and rheumatoid arthritis. These patients
generally have a positive ANA in virtually 100% of the cases. High
titer anti-ribonucleoprotein (RNP) antibodies may be present, generating
a speckled ANA pattern. Anti-RNP is not pathognomonic for mixed
connective tissue disease, since it can be found in low titers in 30% of
the patients with SLE.
Scleroderma (choice D) is characterized by thickening of the skin caused
by swelling and thickening of fibrous tissue, with eventual atrophy of
the epidermis. ANA are often associated with the disease, but the
staining pattern is generally nucleolar.
--------------------------------------------------------------------------------9>The
correct answer is D. Specificity refers to how well a test identifies
persons who do not have the disease in question. In the example, 2900
women do not have breast cancer, and 2540 of these women have a negative
test. Specificity is given by (true negatives)/ (true negatives + false
positives) = 2540/(2540+360) = 2540/2900.
Choice A, 90/100, represents the sensitivity of the test; that is, the proportion of women with the condition who test positive.
Choice B, 90/450, gives the predictive value of a positive test. Of the
450 women who tested positive, 90 actually had the condition.
Choice C, 2540/2550, gives the predictive value of a negative test. Of the 2550 who tested negative, 2540 did not have cancer.
Choice E, (90+2540)/3000, refers to the efficiency of a test; that is,
the proportion of all subjects who were correctly classified by the
test.
--------------------------------------------------------------------------------10>The
correct answer is A. The disease is Pneumocystis pneumonia, which is
caused by an agent now believed to be a fungus rather than a true
bacteria. Pneumocystis carinii pneumonia is seen in immunocompromised
patients, particularly in those with AIDS, cancer, and in malnourished
children. It can be the AIDS-defining illness.
Congestive heart failure (choice B) predisposes the patient to pulmonary edema.
Pulmonary embolus (choice C) can cause pulmonary infarction or sudden death.
Rheumatoid arthritis (choice D), particularly in miners, can cause
formation of lung nodules similar to subcutaneous rheumatoid nodules.
Systemic lupus erythematosus (choice E) can cause pleuritis, but is not
associated with a significantly increased incidence of pneumonia.
--------------------------------------------------------------------------------11>The
correct answer is C. The disease is Fragile X Syndrome, which is a
familial form of mental retardation that is roughly as common as Down's
syndrome. The phenotype has a variable expression, but can include large
head circumference at birth, perinatal complications (premature birth,
asphyxia, seizures), and possibly increased incidence of sudden infant
death syndrome. Later, mental retardation, particularly involving
language, and symptoms suggestive of attention deficit disorder and/or
autism may appear. Features suggestive of connective tissue disorder
(lax skin and joints, flat feet, large ears) are common. After puberty,
there may be a long narrow face with prominent jaw and nasal bridge.
Macro-orchidism is also common after puberty. Mitral valve prolapse and
aortic root dilatation, which may appear in late adolescence or
adulthood, are among the most serious complications of this disorder.
Aortic regurgitation related to aortic root dilatation, not stenosis (choice A), can be a problem in this population.
Common congenital cardiac malformations such as atrial septal defect
(choice B) or ventricular septal defect (choice E) are not features of
Fragile X syndrome, but can be seen with Down's syndrome.
Tricuspid atresia (choice D) is a serious congenital cardiac
malformation limiting flow into the right ventricle, but it is not part
of Fragile X syndrome.
--------------------------------------------------------------------------------12>The
correct answer is E. Because the right main bronchus is wider and more
vertical than the left, foreign objects are more likely to be aspirated
into the right main bronchus. The superior segmental bronchus of the
lower lobar bronchus is the only segmental bronchus that exits from the
posterior wall of the lobar bronchi. Therefore, if a patient is supine
at the time of aspiration, the object is most likely to enter the
superior segmental bronchus of the lower lobe.
None of the segmental bronchi of the left lung (choices A and D) are
likely to receive the object because the object is less likely to enter
the left main bronchus.
The apical segment of the right upper lobe (choice B) is not likely to
receive the foreign object because of the sharp angle that the upper
lobar bronchus makes with the right main bronchus and the sharp angle
that the apical segmental bronchus makes with the lobar bronchus.
The medial segmental bronchus of the right middle lobe (choice C) arises
from the anterior wall of the right middle lobar bronchus. Therefore,
when the patient is supine, the effect of gravity will tend to prevent
the object from entering this segmental bronchus.
--------------------------------------------------------------------------------13>The
correct answer is A. The disease described is Huntington's disease,
which is now known to be related to an expanded trinucleotide tandem
repeat on the short arm of chromosome 4. The number of trinucleotide
repeats frequently increases in succeeding generations during the
process of spermatogenesis.
Prader-Willi and Angelman syndromes are frequently cited examples of genetic diseases involving genomic imprinting (choice B).
Duchenne's muscular dystrophy is an example of a disease that is
frequently due to a large deletion in a single gene (choice C).
Single amino acid substitutions (choice D) are common in recessive diseases such as sickle cell anemia.
Translocations (choice E) occur in disorders such as chronic myelogenous
leukemia (CML; Philadelphia chromosome) and some cases of Down's
syndrome.
--------------------------------------------------------------------------------14>The
correct answer is A. The mass is an abdominal aortic aneurysm,
typically found in older men. Such aneurysms are almost always related
to the formation of complicated atherosclerotic plaques in the aorta.
Associated coronary artery disease is commonplace.
Bacterial infection (choice B) can cause "mycotic" aneurysms; these usually involve smaller vessels.
The small berry aneurysms that can involve the circle of Willis are congenital anomalies (choice C).
Cystic medial degeneration (choice D) is related to the development of dissecting aneurysms (actually dissecting hematomas).
Tertiary syphilis (choice E) typically causes aneurysms of the root and arch of the aorta, rather than the descending aorta.
--------------------------------------------------------------------------------15>The
correct answer is C. The cell is spindle-shaped like a fibroblast;
however, the difference is that the cytoplasm contains several bundles
of microfilaments. These bundles are parallel to the long axis of the
cell and are seen immediately beneath the cell membrane and within the
cytoplasm. Densities, comparable to Z-lines, can be seen along some of
these bundles. The microfilaments are responsible for the contractile
properties of this cell. These contractile properties, in addition to
the cell's ability to link with collagen, function in wound closure in
the healing process. Dupuytren's contracture, which is a contracture of
the palmar fascia, is caused by interaction of these cells with collagen
fibrils of the fascia.
The endothelial cell (choice A) lines vessels. There are no vessels in the photomicrograph.
The myoepithelial cell (choice B) contains microfilaments and is
contractile. However, it is closely associated with glandular epithelium
(not apparent here).
The pericyte (choice D) is a multipotential connective tissue cell found
near or around blood vessels, but it does not contain microfilament
bundles such as these. There are no vessels apparent in the
photomicrograph.
The smooth muscle cell (choice E) is joined by junctions to other smooth
muscle cells, arranged in bundles. Microfilaments make up most of the
cytoplasm of such cells, with the nucleus in a central location.
--------------------------------------------------------------------------------16>The
correct answer is B. The structure of the cochlea is complex. The organ
of Corti contains hair cells from the cochlear branch of the
vestibulocochlear nerve (CN VIII). These cells rest on the basilar
membrane (choice A), which separates the scala tympani (choice D) from
the scala media. The hairs of the hair cells are embedded in the
tectorial membrane, and movement of the basilar membrane below the cells
tends to bend the hairs, which generates action potentials by the hair
cells. The tectorial membrane that lies on the hair cells does not form a
boundary between the different scala; the membrane separating the scala
media from the scala vestibuli (choice E) is Reissner's (vestibular)
membrane (choice C).
--------------------------------------------------------------------------------17>The
correct answer is C. The pretracheal layer of the cervical fascia runs
from the investing layers in both sides of the lateral neck and splits
to enclose the thyroid gland. Superiorly, it attaches to the laryngeal
cartilages; inferiorly, it fuses with the pericardium. As a result of
these connections, the thyroid gland moves with laryngeal movements.
The carotid sheath (choice A) contains the vagus nerve, internal jugular vein, carotid artery, and lymph nodes.
The investing layer of the deep cervical fascia (choice B) splits to enclose the trapezius and sternocleidomastoid muscles.
The prevertebral fascia (choice D) covers muscles arising from the vertebrae.
The superficial fascia (choice E) is immediately deep to the platysma muscle
--------------------------------------------------------------------------------18>The
correct answer is D. The best markers for identification of B cells are
CD19, CD20, and CD21. The CD21 marker is a receptor for EBV
(Epstein-Barr Virus).
The CD3 marker (choice A) is present on all T cells with either a CD4 or
CD8 marker. This is the marker that is used to identify total T cell
count in a blood sample. The CD3 marker is used for signal transduction
in the different T cells.
The CD4 marker (choice B) is used to identify T helper cells. These are
the cells that recognize exogenous peptides presented on MHC class II
molecules by macrophages. CD4+ T helper cells are also involved in
cell-mediated delayed hypersensitivity, production of cytokines for
stimulation of antibody production by B cells, and stimulation of
macrophages.
The CD8 marker (choice C) is used to identify cytotoxic T cells. These
are the cells that recognize viral epitopes attached to the MHC class I
molecules of a virally infected cell.
The CD56 marker (choice E) is used to identify NK(natural killer) cells.
These cells are important in innate host defense, specializing in
killing virally infected cells and tumor cells by secreting granzymes
and perforins.
--------------------------------------------------------------------------------19>The
correct answer is A. In a syndrome called cleidocranial dysostosis,
absence of part of the clavicles accompanies a broad skull, and facial
and dental anomalies. Note that you could also have answered this
question by noting that of the bones listed, only the clavicles form by
intramembranous ossification.
The femurs (choice B), metatarsals (choice C), phalanges (choice D), and
tibias (choice E) are cartilaginous (formed by endochondral
ossification) rather than membranous bones.
--------------------------------------------------------------------------------20>The
correct answer is D. Metformin is a drug that is often used in
conjunction with oral hypoglycemic agents for the treatment of NIDDM.
Its mechanism of action is two-fold: (1) it decreases the production of
glucose in the liver; (2) it increases the uptake of glucose in the
liver. Metformin has no effect on the secretion of pancreatic insulin.
Acetohexamide (choice A) is an oral hypoglycemic agent that is a
sulfonylurea derivative. It stimulates secretion of insulin from the
pancreas.
Chlorpropamide (choice B) is an oral hypoglycemic agent that is a
sulfonylurea derivative. It stimulates secretion of insulin from the
pancreas.
Glyburide (choice C) is a sulfonylurea derivative that stimulates insulin secretion from the pancreas.
Tolbutamide (choice E) is a sulfonylurea derivative that stimulates insulin secretion from the pancreas.
21The correct answer is A. The patient is presenting with signs and
symptoms of acute cholecystitis, which is associated with gallstones in
more than 90% of all cases. This condition occurs when a stone becomes
impacted in the cystic duct and inflammation develops behind the
obstruction. The acute attack is often precipitated by a large fatty
meal, and is characterized by the sudden appearance of severe, steady
pain localized to the epigastrium or right hypochondrium. Laboratory
findings often include elevated white blood cells (2,000 - 15,000/mL).
Total serum bilirubin values of 1-4 mg/dL may be seen in some instances,
and serum amylase may be elevated. In noncomplicated cases, treatment
often includes IV alimentation, analgesics, and antibiotics, as well as
withholding of oral feedings. Meperidine is the narcotic of choice since
it is least likely to cause spasm of the sphincter of Oddi, probably
because of its antimuscarinic properties. It is therefore preferred over
morphine (choice B), oxycodone (choice D), and propoxyphene (choice E).
Furthermore, propoxyphene is a narcotic agonist with mild analgesic
properties; hence, it would most likely not be able to effectively treat
this patient's severe pain.
Naproxen (choice C) is a nonsteroidal anti-inflammatory drug (NSAID)
indicated for the treatment of mild to moderate pain; this agent would
most likely not provide sufficient pain control for this patient.
--------------------------------------------------------------------------------22>The
correct answer is A. When the head of the humerus dislocates from the
glenohumeral joint, it exits inferiorly, where the joint capsule is the
weakest. Immediately inferior to the glenohumeral joint, the axillary
nerve exits from the axilla by passing through the quadrangular space.
At this location, the downward movement of the head of the humerus can
stretch the axillary nerve. The axillary nerve innervates the deltoid
muscle after leaving the axilla.
The dorsal scapular nerve (choice B) passes along the medial border of
the scapula to innervate the rhomboid muscles. The nerve does not pass
in the region of the glenohumeral joint.
The lateral and medial pectoral nerves (choices C and D) branch from the
lateral and medial cords of the brachial plexus, respectively, and exit
through the anterior wall of the axilla to innervate the pectoralis
major and minor. These nerves do not pass in the region of the
glenohumeral joint.
The suprascapular nerve (choice E) is a branch of the upper trunk of the
brachial plexus and passes over the superior border of the scapula to
innervate the supraspinatus and infraspinatus muscles. This nerve does
not pass in the region of the glenohumeral joint.
--------------------------------------------------------------------------------23>The
correct answer is D. This patient most likely has subacute
granulomatous (de Quervain's) thyroiditis, which frequently develops
after a viral infection. Microscopically, it is characterized by
microabscess formation within the thyroid, eventually progressing to
granulomatous inflammation with multinucleated giant cells. Clinically,
patients may experience fever, sudden painful enlargement of the
thyroid, and/or symptoms of transient hyperthyroidism. The disease
usually abates within 6 to 8 weeks.
Diffuse nontoxic goiter (choice A) by definition does not produce hyperthyroidism.
The hyperthyroidism of Graves disease (choice B) does not spontaneously remit.
Hashimoto's thyroiditis (choice C) can cause transient hyperthyroidism, but then goes on to cause hypothyroidism.
Subacute lymphocytic thyroiditis (choice E) can cause transient hyperthyroidism, but is characteristically painless.
25>
The correct answer is E. Hypersecretion of insulin by a pancreatic b
cell tumor is a major cause of fasting hypoglycemia (plasma glucose is
not increased, choice D). Symptoms are related to neuroglycopenia and
could include recurrent central nervous system dysfunction during
fasting or exercise. While proinsulin only makes up approximately 20% of
plasma immunoreactive insulin in normal individuals, in patients with
an insulinoma it contributes 30-90% of the immunoreactive insulin.
Hence, plasma levels of proinsulin are increased. The increased
secretion of insulin by the tumor will also lead to an increase in C
peptide secretion (not decreased, choice B) since b cells secrete
insulin and C peptide on a one-to-one molar ratio. Given the prolonged
hypoglycemia, the amount of glycosylated hemoglobin may also be
decreased, although this is not a universal finding. Certainly, an
increase in glycosylated hemoglobin would not be expected (choice A).
Glucagon secretion is increased by hypoglycemia and its plasma level in a
patient with an insulinoma would be expected to be increased compared
to normal (not decreased, choice C
--------------------------------------------------------------------------------26>The
correct answer is A. This question is really asking you two things.
First, it tests whether you know that lymphocytosis is associated with
viral infection. Second, it tests your knowledge of lymphocytes'
histological appearance. Note that these cells are generally small and
normally constitute 25%-33% of leukocytes. Two types of lymphocytes have
been distinguished: T cells (involved in cell-mediated immunity) and B
cells (involved in humoral immunity).
Monocytes are precursors of osteoclasts and liver Kupffer cells (choice
B) and also give rise to tissue macrophages and alveolar macrophages.
Platelets contain a peripheral hyalomere and central granulomere (choice C).
Neutrophils have azurophilic granules and multilobed nuclei (choice D).
They increase in number in response to bacterial infection.
Erythrocytes remain in the circulation for about 120 days (choice E).
--------------------------------------------------------------------------------27>The
correct answer is D. The lesion is a malignant melanoma. Melanomas can
develop either de novo or in an existing mole. Sunlight exposure is a
significant risk factor and fair-skinned persons are at increased risk
of developing melanoma. The most significant factor for long term
prognosis is the depth of the lesion, since the superficial dermis lies
about 1 mm under the skin surface, and penetration to this depth is
associated with a much higher incidence of metastasis than is seen with a
more superficial location.
The circumference of the lesion (choice A) is much less important than
depth, since one form of melanoma (superficial spreading) can still have
good prognosis despite large size, if it has not extended to the depth
of the superficial dermal lymphatic bed.
The darkness (choice B) or degree of variation in color (choice C) do
not have prognostic significance once melanoma is diagnosed.
Irregularity, or fuzziness at the border (choice E) of a mole-like
lesion is a good clue to potential malignancy, but does not affect
prognosis once a melanoma is diagnosed.
--------------------------------------------------------------------------------28>The
correct answer is A. Most of the venous drainage of the skin of the
lower extremity is to the long saphenous vein, the accompanying
lymphatics of which drain into the superficial group of the inguinal
lymph nodes. However, the skin drained by the short saphenous vein,
including that of the lateral aspect of the dorsum of the foot, is an
exception to this rule. Lymphatic fluid from this area drains into
lymphatics accompanying the short saphenous vein, then drains into lymph
nodes behind the knee in the popliteal fossa.
The lateral side of the thigh (choice B), the medial side of the leg
below the knee (choice C), the medial side of the sole of the foot
(choice D), and the medial side of the thigh (choice E) all drain to the
superficial inguinal nodes.
--------------------------------------------------------------------------------29>The
correct answer is E. The child has "rat-bite fever." This occurs in two
forms with somewhat similar clinical manifestations. The form this
child has is the Haverhill fever form, caused by Streptobacillus
moniliformis and characterized by a short (often 1-3 days) incubation
period. The Haverhill form is more common in the United States than the
Sodoku form, which is caused by Spirillium minus, has a 1-4 week
incubation period, and is most prevalent in Japan. One of the problems
with diagnosing these diseases is that the victims are usually young
children, and the bite site may be inapparent by the time the disease
becomes severe enough for the child to be taken to a doctor.
Borrelia burgdorferi (choice A) causes Lyme disease, which is
characterized by an expanding erythematous rash, arthralgias, and
eventual nervous system involvement.
Pseudomonas mallei (choice B) causes glanders, which generally affects horses or humans in close contact with equines.
Pseudomonas pseudomallei (choice C) causes melioidosis, a rare pulmonary disease found mostly in Southeast Asia.
Spirillium minus (choice D) causes the Sodoku form of rat-bite fever.
--------------------------------------------------------------------------------30>The
correct answer is A. Urticaria (hives) are pruritic wheals that form
after mast cells degranulate and trigger localized dermal edema with
dilated superficial lymphatic channels. The mast cell degranulation is
sometimes, but not always, triggered by IgE-antigen interactions.
Granular complement and IgG deposition at the dermal/epidermal junction
(choice B) is a characteristic of systemic lupus erythematosus.
Microscopic blisters (choice C) are a characteristic of dermatitis herpetiformis.
Munro abscesses (choice D) are a characteristic of psoriasis.
Solar elastosis (choice E) is found in actinic keratoses.
--------------------------------------------------------------------------------31>The
correct answer is B. Direct inguinal hernias enter the inguinal canal
by tearing through the posterior wall of that structure. The typical
location for this type of hernia is through the inguinal triangle,
bounded laterally by the inferior epigastric artery, medially by the
lateral border of the rectus abdominis, and inferiorly by the inguinal
ligament. Direct inguinal hernias pass medial to the inferior epigastric
artery, whereas indirect inguinal hernias pass lateral to the inferior
epigastric artery because the deep inguinal ring is lateral to the
artery.
Indirect inguinal hernias are covered by all three layers of the
spermatic fascia (choice A). Direct inguinal hernias are covered by
fewer than all three layers because the direct inguinal hernia tears
through one or more layers of fascia as it emerges though the abdominal
wall.
The lateral border of the rectus abdominis muscle (choice C) forms the
medial border of the inguinal triangle. All inguinal hernias pass
lateral to the rectus abdominis.
Femoral hernias pass posterior to the inguinal ligament (choice D).
Inguinal hernias emerge through the superficial inguinal ring, which is
superior to the inguinal ligament. Inguinal hernias that descend below
the inguinal ligament pass anterior to the ligament.
Indirect inguinal hernias pass through the deep inguinal ring (choice
E); direct inguinal hernias do not. Both types of inguinal hernias pass
through the superficial inguinal ring.
32>The correct answer is A. The patient has a severe, potentially
fatal, pneumonia with prominent systemic symptoms. Culture on BCYE is
the specific clue that the organism is Legionella pneumophila. The
disease is respiratory Legionellosis, also known as Legionnaire's
disease, because the disease was first described when it occurred in
epidemic form following an American Legion convention at a Philadelphia
hotel. Patients tend to be older (40-70 years old) and may have risk
factors including cigarette use, alcoholism, diabetes, chronic illness,
or immunosuppressive therapy.
Listeria monocytogenes (choice B) causes listeriosis and is not a notable cause of pneumonia.
Spirillium minus (choice C) is a cause of rat-bite fever and is not a notable cause of pneumonia.
Staphylococcus aureus (choice D) can cause pneumonia, but is easily cultured on routine media.
Streptococcus pneumoniae (choice E) can cause pneumonia, but is easily cultured on routine media.
-33The
correct answer is C. Sensitivity is defined as the ability of a test to
detect the presence of a disease in those who truly have the disease.
It is calculated as the number of people with a disease who test
positive (true positive) divided by the total number of people who have
the disease (true positive + false negative). In this case, sensitivity
equals the number of people with HIV antibody who test positive (100)
divided by the total number of people who have HIV antibody (120). This
yields 100/120 = 83% (not a very sensitive test).
11% (choice A) corresponds to the prevalence of the disease in the
tested population, which in this case equals the total number of people
with HIV antibody (true positive + false negative = 100 + 20 = 120)
divided by the total number of people tested (100 + 20 + 50 + 950 =
1120). This yields 120/1120 = 11%.
67% (choice B) corresponds to the positive predictive value of the test,
which equals the number of people with the disease who test positive
(true positive