NBME 30
1
Exam Section 1: Item 1 of fifty
National Board of Medical Examiners®
Comprehensive Basic Science Self-Assessment
1. Shortly after shipping, a full-time period male new child is located to have black hair with a
white forelock. His mother, a brunette, additionally has a white forelock and wears hearing
aids. Physical examination indicates heterochromia of irides. Otoacoustic emissions trying
out and
mind stem auditory evoked responses show bilateral sensorineural listening to loss. Which
of the subsequent is the most possibly reason of the findings on this patient?
A) Abnormal neural crest development
B) Abnormality of connexins
C) Deficiency of homogentisic acid oxidase pastime
D) Deficiency of tyrosinase activity
E) Failure of internalization of melanin granules by way of keratinocytes
F) Failure of melanosome transportation along dendrites - ANS-A.
Abnormal neural crest development ends in Waardenburg syndrome. Waardenburg
syndrome is a syndrome of patchy depigmentation of the pores and skin, hair, irises, and
cochlear dysfunction that mainly illustrates an autosomal dominant inheritance sample.
Because of
genetic mutations of genes encoding transcription elements, neural crest cells do no longer
well differentiate into melanoblasts (melanocyte precursors), or melanoblasts do now not
migrate to their suitable location. Patients normally have a white forelock and eyelashes,
depigmented pores and skin patches, iridic heterochromia, and sensorineural deafness. The
eyes will also be laterally displaced. The clinical analysis can be showed with genetic
checking out. Treatment consists of audiologic assessment and genetic consultation.
Incorrect Answers: B, C, D, E, and F.
An abnormality of connexins (Choice B) would result in atypical formation of the plasma
membrane channels of numerous cellular sorts. Different combos of sensorineural listening
to loss, ichthyosis, alopecia, and peripheral neuropathy may also arise. Depigmentation
would be atypical.
Deficiency of homogentisic acid oxidase activity (Choice C) could cause decreased
metabolism of the amino acids phenylalanine and tyrosine, which instead degrade into
homogentisic acid. Homogentisic acid accumulates inside the skin and joints, causing
extended
pigmentation and arthritis, respectively. Depigmentation might be strange.
Deficiency of tyrosinase activity (Choice D) takes place in oculocutaneous albinism, which
provides with uniformly hypopigmented hair and skin (versus the patchy depigmentation of
Waardenburg syndrome) and eye abnormalities (eg, iris hypopigmentation, refractive
errors, nystagmus). In tyrosinase deficiency, melanocytes are not able to synthesize melanin
from the amino acid tyrosine. Iridic heterochromia and sensorineural deafnes
2
,Exam Section 1: Item 2 of fifty
National Board of Medical Examiners®
Comprehensive Basic Science Self-Assessment
2. During an experiment, an answer of mixed fatty acids is injected into the duodenum of an
experimental animal. Under these conditions, the clearance charge of an intravenous
glucose load from the flow is doubled. In evaluation, an injection of an identical
quantity quantity of zero.Nine% saline into the duodenum has an awful lot much less impact
on the plasma clearance price of glucose. These findings are most probably caused by the
secretion of which of the subsequent hormones?
A) Gastrin
B) Glucose-dependent insulinotropic peptide
C) Motilin
D) Secretin
E) Somatostatin - ANS-B.
Glucose-dependent insulinotropic peptide (GIP) is secreted by using K cells within the
duodenum and jejunum and functions to decrease gastric acid manufacturing and stimulate
insulin release from the pancreas. Its secretion is promoted by way of the presence of fatty
acids, amino
acids, and intestinal glucose. While serum glucose additionally stimulates insulin secretion
with the aid of the pancreas, the impact of intraluminal glucose on GIP and subsequent
insulin secretion results in extended concentrations of insulin as compared to parenteral
glucose
management. Insulin promotes peripheral tissue uptake of glucose, glycolysis, glycogen
synthesis, protein synthesis, and fatty acid synthesis, resulting in reduced glucose
concentration within the serum.
Incorrect Answers: A, C, D, and E.
Gastrin (Choice A) is produced by way of G cells within the gastric antrum and stimulates
parietal cells in the gastric frame to supply hydrochloric acid. Gastric acid has no effect on
serum glucose attention.
Motilin (Choice C) is secreted by means of the small intestine and stimulates intestinal
peristalsis. Motilin receptors are targeted with the aid of erythromycin and metoclopramide,
used therapeutically in gastroparesis.
Secretin (Choice D) is produced via duodenal S cells. It promotes the release of
bicarbonate-wealthy pancreatic secretions and bile and inhibits gastric acid manufacturing.
Somatostatin (Choice E) is a regulatory peptide secreted with the aid of D cells of the
pancreas and gastrointestinal mucosa that inhibits gastric acid and pepsinogen secretion,
gallbladder contraction, and insulin and glucagon release. Somatostatin could have an
oblique
impact on glucose thru counterregulatory motion of each insulin and glucagon.
Educational Objective: Glucose-structured insulinotropic peptide (GIP) is secreted with the
aid of K cells inside the duodenum and jejunum, and it capabilities to decrease gastric acid
production and
three
Exam Section 1: Item three of 50
National Board of Medical Examiners®
Comprehensive Basic Science Self-Assessment
three. A fifty three-12 months-old guy involves the doctor due to a 6-day records of
shortness of breath, cough, and pleuritic chest ache. His temperature is 38.9°C (102°F), and
,respirations are 35/min. Sputum is purulent and rust coloured. Physical examination
suggests
decreased breath sounds, and crackles are heard on the left base. A Gram stain of sputum
indicates gram-tremendous diplococci. A chest x-ray indicates left-sided lobar consolidation.
Which of the subsequent anatomic structures maximum probably allowed fast unfold of
organisms between alveoli to involve the whole left lobe in this patient?
A) Alveolar capillaries
B) Germinal centers
C) Lymphatic capillaries
D) Pores of Kohn
E) Vascular sinusoids - ANS-D.
The pores of Kohn shape connections among alveoli and are found in ordinary lung tissue.
They are composed, at the least in component, of type Il alveolar cells and allow for the
passage of air, fluid, phagocytes, and in the placing of pneumonia, micro organism among
adjacent
alveoli. By allowing equilibration between adjacent alveoli, the pores of Kohn resource in
normal oxygenation and within the prevention of atelectasis. However, infectious organisms
and infection may additionally unfold among adjacent alveoli via those apertures.
Incorrect Answers: A, B, C, and E.
Alveolar capillaries (Choice A) surround every alveolus and are essential for gas trade.
However, they do not provide an instantaneous connection between adjoining alveoli,
provided that the alveolar and capillary endothelia remain intact.
Germinal facilities (Choice B) permit for the improvement of B lymphocytes and are vital in
mounting an adaptive immune reaction to pulmonary pathogens. They do no longer form
connections among alveoli.
Lymphatic capillaries (Choice C) allow for the drainage of interstitial fluid from the lung
parenchyma to the lymphatic ducts and ultimately to the coronary heart. These passages do
no longer shape direct anastomoses among adjoining alveoli.
Vascular sinusoids (Choice E) are found in hepatic tissue and create anastomoses among
the portal and systemic circulation, taking into account the alternate of nutrients with
hepatocytes. They are not found in pulmonary tissue.
Educational Objective: The pores of Kohn form connections among alveoli and are found in
normal lung tissue. They permit for the passage of air, fluid, phagocytes, and, in the setting
of pneumonia, bacteria among adjacent alveoli.
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four
Exam Section 1: Item four of fifty
National Board of Medical Examiners®
Comprehensive Basic Science Self-Assessment
, four. A lady new child is born at 39 weeks' gestation following a humdrum pregnancy. The
Apgar rankings are 10 at 1 and five minutes, respectively. The newborn is on the 50th
percentile for period and twenty fifth percentile for weight. She has everyday morphologic
functions. The parents are told she has an enzyme disorder that, if left untreated, will bring
about failure to achieve early developmental milestones, microcephaly, hyperactivity,
seizures, highbrow disability, and a mousy odor of the pores and skin and urine. The affected
person's weight-reduction plan
wishes to comprise which of the subsequent to provide substrate for catecholamine
manufacturing?
A) Dihydroxyphenylalanine
B) Dopamine
C) Epinephrine
D) Norepinephrine
E) Phenylalanine
F) Tyrosine - ANS-F.
Tyrosine dietary supplements are required for catecholamine manufacturing in this patient
with phenylketonuria (PKU). PKU results from a deficiency inside the enzyme phenylalanine
hydroxylase (PAH) that converts phenylalanine to tyrosine. Deficiency results in
accumulation of
phenylalanine and its metabolites phenylacetate and phenyllactate. Rarely, mutations in
enzymes that either produce or recycle tetrahydrobiopterin (BH , that is a cofactor for PAH,
can have similar medical manifestations as traditional PKÚ. Phenylalanine is a
precursor to tyrosine, and tyrosine is used to synthesize catecholamines together with
dopamine, epinephrine, and norepinephrine. Tyrosine is converted to
dihydroxyphenylalanine through tyrosine hydroxylase, accompanied via conversion to
dopamine by way of DOPA-decarboxylase.
Dopamine can finally be converted to norepinephrine, and methylation of norepinephrine
results in formation of epinephrine. Patients with PKU from PAH deficiency require
supplementation with tyrosine to bypass the dysfunctional enzymatic step of
converting phenylalanine to tyrosine.
Incorrect Answers: A, B, C, D, and E.
Dihydroxyphenylalanine (Choice A), abbreviated as DOPA, is a precursor to dopamine and
is formed through the movement of tyrosine hydroxylase. This enzymatic pathway is
practical in patients with PKU so supplementation with DOPA isn't always required. Similarly,
dopamine (Choice B) is comprised of DOPA by the enzyme DOPA decarboxylase, while
epinephrine (Choice C) and norepinephrine (Choice D) are made from dopamine via
separate enzymes, none of which might be deficient in PKU. Supplementation of tyrosine is
enough to permit for ordinary synthesis of all of those catecholamines.
Phenylalanine (Choice E) would get worse the signs and symptoms of PKU as the number
one motive of this circumstance is the incapacity to convert phenylalanine to tyrosine.
Educational Objective:
five
Exam Section 1: Item five of 50
National Board of Medical Examiners®
Comprehensive Basic Science Self-Assessment
5. A seventy six-12 months-old girl involves the emergency department due to a 6-hour
records of slight proper low lower back and flank ache. Vital signs are inside ordinary limits.
Physical examination shows mild vertebromediastinal recess (costovertebral attitude)
1
Exam Section 1: Item 1 of fifty
National Board of Medical Examiners®
Comprehensive Basic Science Self-Assessment
1. Shortly after shipping, a full-time period male new child is located to have black hair with a
white forelock. His mother, a brunette, additionally has a white forelock and wears hearing
aids. Physical examination indicates heterochromia of irides. Otoacoustic emissions trying
out and
mind stem auditory evoked responses show bilateral sensorineural listening to loss. Which
of the subsequent is the most possibly reason of the findings on this patient?
A) Abnormal neural crest development
B) Abnormality of connexins
C) Deficiency of homogentisic acid oxidase pastime
D) Deficiency of tyrosinase activity
E) Failure of internalization of melanin granules by way of keratinocytes
F) Failure of melanosome transportation along dendrites - ANS-A.
Abnormal neural crest development ends in Waardenburg syndrome. Waardenburg
syndrome is a syndrome of patchy depigmentation of the pores and skin, hair, irises, and
cochlear dysfunction that mainly illustrates an autosomal dominant inheritance sample.
Because of
genetic mutations of genes encoding transcription elements, neural crest cells do no longer
well differentiate into melanoblasts (melanocyte precursors), or melanoblasts do now not
migrate to their suitable location. Patients normally have a white forelock and eyelashes,
depigmented pores and skin patches, iridic heterochromia, and sensorineural deafness. The
eyes will also be laterally displaced. The clinical analysis can be showed with genetic
checking out. Treatment consists of audiologic assessment and genetic consultation.
Incorrect Answers: B, C, D, E, and F.
An abnormality of connexins (Choice B) would result in atypical formation of the plasma
membrane channels of numerous cellular sorts. Different combos of sensorineural listening
to loss, ichthyosis, alopecia, and peripheral neuropathy may also arise. Depigmentation
would be atypical.
Deficiency of homogentisic acid oxidase activity (Choice C) could cause decreased
metabolism of the amino acids phenylalanine and tyrosine, which instead degrade into
homogentisic acid. Homogentisic acid accumulates inside the skin and joints, causing
extended
pigmentation and arthritis, respectively. Depigmentation might be strange.
Deficiency of tyrosinase activity (Choice D) takes place in oculocutaneous albinism, which
provides with uniformly hypopigmented hair and skin (versus the patchy depigmentation of
Waardenburg syndrome) and eye abnormalities (eg, iris hypopigmentation, refractive
errors, nystagmus). In tyrosinase deficiency, melanocytes are not able to synthesize melanin
from the amino acid tyrosine. Iridic heterochromia and sensorineural deafnes
2
,Exam Section 1: Item 2 of fifty
National Board of Medical Examiners®
Comprehensive Basic Science Self-Assessment
2. During an experiment, an answer of mixed fatty acids is injected into the duodenum of an
experimental animal. Under these conditions, the clearance charge of an intravenous
glucose load from the flow is doubled. In evaluation, an injection of an identical
quantity quantity of zero.Nine% saline into the duodenum has an awful lot much less impact
on the plasma clearance price of glucose. These findings are most probably caused by the
secretion of which of the subsequent hormones?
A) Gastrin
B) Glucose-dependent insulinotropic peptide
C) Motilin
D) Secretin
E) Somatostatin - ANS-B.
Glucose-dependent insulinotropic peptide (GIP) is secreted by using K cells within the
duodenum and jejunum and functions to decrease gastric acid manufacturing and stimulate
insulin release from the pancreas. Its secretion is promoted by way of the presence of fatty
acids, amino
acids, and intestinal glucose. While serum glucose additionally stimulates insulin secretion
with the aid of the pancreas, the impact of intraluminal glucose on GIP and subsequent
insulin secretion results in extended concentrations of insulin as compared to parenteral
glucose
management. Insulin promotes peripheral tissue uptake of glucose, glycolysis, glycogen
synthesis, protein synthesis, and fatty acid synthesis, resulting in reduced glucose
concentration within the serum.
Incorrect Answers: A, C, D, and E.
Gastrin (Choice A) is produced by way of G cells within the gastric antrum and stimulates
parietal cells in the gastric frame to supply hydrochloric acid. Gastric acid has no effect on
serum glucose attention.
Motilin (Choice C) is secreted by means of the small intestine and stimulates intestinal
peristalsis. Motilin receptors are targeted with the aid of erythromycin and metoclopramide,
used therapeutically in gastroparesis.
Secretin (Choice D) is produced via duodenal S cells. It promotes the release of
bicarbonate-wealthy pancreatic secretions and bile and inhibits gastric acid manufacturing.
Somatostatin (Choice E) is a regulatory peptide secreted with the aid of D cells of the
pancreas and gastrointestinal mucosa that inhibits gastric acid and pepsinogen secretion,
gallbladder contraction, and insulin and glucagon release. Somatostatin could have an
oblique
impact on glucose thru counterregulatory motion of each insulin and glucagon.
Educational Objective: Glucose-structured insulinotropic peptide (GIP) is secreted with the
aid of K cells inside the duodenum and jejunum, and it capabilities to decrease gastric acid
production and
three
Exam Section 1: Item three of 50
National Board of Medical Examiners®
Comprehensive Basic Science Self-Assessment
three. A fifty three-12 months-old guy involves the doctor due to a 6-day records of
shortness of breath, cough, and pleuritic chest ache. His temperature is 38.9°C (102°F), and
,respirations are 35/min. Sputum is purulent and rust coloured. Physical examination
suggests
decreased breath sounds, and crackles are heard on the left base. A Gram stain of sputum
indicates gram-tremendous diplococci. A chest x-ray indicates left-sided lobar consolidation.
Which of the subsequent anatomic structures maximum probably allowed fast unfold of
organisms between alveoli to involve the whole left lobe in this patient?
A) Alveolar capillaries
B) Germinal centers
C) Lymphatic capillaries
D) Pores of Kohn
E) Vascular sinusoids - ANS-D.
The pores of Kohn shape connections among alveoli and are found in ordinary lung tissue.
They are composed, at the least in component, of type Il alveolar cells and allow for the
passage of air, fluid, phagocytes, and in the placing of pneumonia, micro organism among
adjacent
alveoli. By allowing equilibration between adjacent alveoli, the pores of Kohn resource in
normal oxygenation and within the prevention of atelectasis. However, infectious organisms
and infection may additionally unfold among adjacent alveoli via those apertures.
Incorrect Answers: A, B, C, and E.
Alveolar capillaries (Choice A) surround every alveolus and are essential for gas trade.
However, they do not provide an instantaneous connection between adjoining alveoli,
provided that the alveolar and capillary endothelia remain intact.
Germinal facilities (Choice B) permit for the improvement of B lymphocytes and are vital in
mounting an adaptive immune reaction to pulmonary pathogens. They do no longer form
connections among alveoli.
Lymphatic capillaries (Choice C) allow for the drainage of interstitial fluid from the lung
parenchyma to the lymphatic ducts and ultimately to the coronary heart. These passages do
no longer shape direct anastomoses among adjoining alveoli.
Vascular sinusoids (Choice E) are found in hepatic tissue and create anastomoses among
the portal and systemic circulation, taking into account the alternate of nutrients with
hepatocytes. They are not found in pulmonary tissue.
Educational Objective: The pores of Kohn form connections among alveoli and are found in
normal lung tissue. They permit for the passage of air, fluid, phagocytes, and, in the setting
of pneumonia, bacteria among adjacent alveoli.
%three-D
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Lab Values
Calculator
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Pause
four
Exam Section 1: Item four of fifty
National Board of Medical Examiners®
Comprehensive Basic Science Self-Assessment
, four. A lady new child is born at 39 weeks' gestation following a humdrum pregnancy. The
Apgar rankings are 10 at 1 and five minutes, respectively. The newborn is on the 50th
percentile for period and twenty fifth percentile for weight. She has everyday morphologic
functions. The parents are told she has an enzyme disorder that, if left untreated, will bring
about failure to achieve early developmental milestones, microcephaly, hyperactivity,
seizures, highbrow disability, and a mousy odor of the pores and skin and urine. The affected
person's weight-reduction plan
wishes to comprise which of the subsequent to provide substrate for catecholamine
manufacturing?
A) Dihydroxyphenylalanine
B) Dopamine
C) Epinephrine
D) Norepinephrine
E) Phenylalanine
F) Tyrosine - ANS-F.
Tyrosine dietary supplements are required for catecholamine manufacturing in this patient
with phenylketonuria (PKU). PKU results from a deficiency inside the enzyme phenylalanine
hydroxylase (PAH) that converts phenylalanine to tyrosine. Deficiency results in
accumulation of
phenylalanine and its metabolites phenylacetate and phenyllactate. Rarely, mutations in
enzymes that either produce or recycle tetrahydrobiopterin (BH , that is a cofactor for PAH,
can have similar medical manifestations as traditional PKÚ. Phenylalanine is a
precursor to tyrosine, and tyrosine is used to synthesize catecholamines together with
dopamine, epinephrine, and norepinephrine. Tyrosine is converted to
dihydroxyphenylalanine through tyrosine hydroxylase, accompanied via conversion to
dopamine by way of DOPA-decarboxylase.
Dopamine can finally be converted to norepinephrine, and methylation of norepinephrine
results in formation of epinephrine. Patients with PKU from PAH deficiency require
supplementation with tyrosine to bypass the dysfunctional enzymatic step of
converting phenylalanine to tyrosine.
Incorrect Answers: A, B, C, D, and E.
Dihydroxyphenylalanine (Choice A), abbreviated as DOPA, is a precursor to dopamine and
is formed through the movement of tyrosine hydroxylase. This enzymatic pathway is
practical in patients with PKU so supplementation with DOPA isn't always required. Similarly,
dopamine (Choice B) is comprised of DOPA by the enzyme DOPA decarboxylase, while
epinephrine (Choice C) and norepinephrine (Choice D) are made from dopamine via
separate enzymes, none of which might be deficient in PKU. Supplementation of tyrosine is
enough to permit for ordinary synthesis of all of those catecholamines.
Phenylalanine (Choice E) would get worse the signs and symptoms of PKU as the number
one motive of this circumstance is the incapacity to convert phenylalanine to tyrosine.
Educational Objective:
five
Exam Section 1: Item five of 50
National Board of Medical Examiners®
Comprehensive Basic Science Self-Assessment
5. A seventy six-12 months-old girl involves the emergency department due to a 6-hour
records of slight proper low lower back and flank ache. Vital signs are inside ordinary limits.
Physical examination shows mild vertebromediastinal recess (costovertebral attitude)
