NBME EXAM SCRIPT 2026 FULL
SOLUTIONS WITH ACCURATE ANSWERS
⫸2
Exam Section 1: Item 2 of 50
National Board of Medical Examiners®
Comprehensive Basic Science Self-Assessment
2. During an experiment, a solution of mixed fatty acids is injected into
the duodenum of an experimental animal. Under these conditions, the
clearance rate of an intravenous glucose load from the circulation is
doubled. In contrast, an injection of an equal
volume amount of 0.9% saline into the duodenum has much less effect
on the plasma clearance rate of glucose. These findings are most likely
caused by the secretion of which of the following hormones?
A) Gastrin
B) Glucose-dependent insulinotropic peptide
C) Motilin
D) Secretin
E) Somatostatin Answer: B.
Glucose-dependent insulinotropic peptide (GIP) is secreted by K cells in
the duodenum and jejunum and functions to decrease gastric acid
production and stimulate insulin release from the pancreas. Its secretion
is promoted by the presence of fatty acids, amino
acids, and intestinal glucose. While serum glucose also stimulates
insulin secretion by the pancreas, the effect of intraluminal glucose on
GIP and subsequent insulin secretion leads to increased concentrations
of insulin compared to parenteral glucose
,administration. Insulin promotes peripheral tissue uptake of glucose,
glycolysis, glycogen synthesis, protein synthesis, and fatty acid
synthesis, resulting in decreased glucose concentration in the serum.
Incorrect Answers: A, C, D, and E.
Gastrin (Choice A) is produced by G cells in the gastric antrum and
stimulates parietal cells within the gastric body to produce hydrochloric
acid. Gastric acid has no effect on serum glucose concentration.
Motilin (Choice C) is secreted by the small intestine and stimulates
intestinal peristalsis. Motilin receptors are targeted by erythromycin and
metoclopramide, used therapeutically in gastroparesis.
Secretin (Choice D) is produced by duodenal S cells. It promotes the
release of bicarbonate-rich pancreatic secretions and bile and inhibits
gastric acid production.
Somatostatin (Choice E) is a regulatory peptide secreted by D cells of
the pancreas and gastrointestinal mucosa that inhibits gastric acid and
pepsinogen secretion, gallbladder contraction, and insulin and glucagon
release. Somatostatin would have an indirect
effect on glucose through counterregulatory action of both insulin and
glucagon.
Educational Objective: Glucose-dependent insulinotropic peptide (GIP)
is secreted by K cells in the duodenum and jejunum, and it functions to
decrease gastric acid production and
⫸3
Exam Section 1: Item 3 of 50
National Board of Medical Examiners®
Comprehensive Basic Science Self-Assessment
,3. A 53-year-old man comes to the physician because of a 6-day history
of shortness of breath, cough, and pleuritic chest pain. His temperature is
38.9°C (102°F), and respirations are 35/min. Sputum is purulent and rust
colored. Physical examination shows
decreased breath sounds, and crackles are heard at the left base. A Gram
stain of sputum shows gram-positive diplococci. A chest x-ray shows
left-sided lobar consolidation. Which of the following anatomic
structures most likely allowed rapid spread of
organisms between alveoli to involve the entire left lobe in this patient?
A) Alveolar capillaries
B) Germinal centers
C) Lymphatic capillaries
D) Pores of Kohn
E) Vascular sinusoids Answer: D.
The pores of Kohn form connections between alveoli and are present in
normal lung tissue. They are composed, at least in part, of type Il
alveolar cells and allow for the passage of air, fluid, phagocytes, and in
the setting of pneumonia, bacteria between adjacent
alveoli. By allowing equilibration between adjacent alveoli, the pores of
Kohn aid in normal oxygenation and in the prevention of atelectasis.
However, infectious organisms and inflammation may also spread
between adjacent alveoli through these apertures.
Incorrect Answers: A, B, C, and E.
Alveolar capillaries (Choice A) surround each alveolus and are crucial
for gas exchange. However, they do not provide a direct connection
between adjacent alveoli, provided that the alveolar and capillary
endothelia remain intact.
, Germinal centers (Choice B) allow for the development of B
lymphocytes and are important in mounting an adaptive immune
response to pulmonary pathogens. They do not form connections
between alveoli.
Lymphatic capillaries (Choice C) allow for the drainage of interstitial
fluid from the lung parenchyma to the lymphatic ducts and eventually to
the heart. These passages do not form direct anastomoses between
adjacent alveoli.
Vascular sinusoids (Choice E) are present in hepatic tissue and create
anastomoses between the portal and systemic circulation, allowing for
the exchange of nutrients with hepatocytes. They are not present in
pulmonary tissue.
Educational Objective: The pores of Kohn form connections between
alveoli and are present in normal lung tissue. They allow for the passage
of air, fluid, phagocytes, and, in the setting of pneumonia, bacteria
between adjacent alveoli.
%3D
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⫸4
Exam Section 1: Item 4 of 50
SOLUTIONS WITH ACCURATE ANSWERS
⫸2
Exam Section 1: Item 2 of 50
National Board of Medical Examiners®
Comprehensive Basic Science Self-Assessment
2. During an experiment, a solution of mixed fatty acids is injected into
the duodenum of an experimental animal. Under these conditions, the
clearance rate of an intravenous glucose load from the circulation is
doubled. In contrast, an injection of an equal
volume amount of 0.9% saline into the duodenum has much less effect
on the plasma clearance rate of glucose. These findings are most likely
caused by the secretion of which of the following hormones?
A) Gastrin
B) Glucose-dependent insulinotropic peptide
C) Motilin
D) Secretin
E) Somatostatin Answer: B.
Glucose-dependent insulinotropic peptide (GIP) is secreted by K cells in
the duodenum and jejunum and functions to decrease gastric acid
production and stimulate insulin release from the pancreas. Its secretion
is promoted by the presence of fatty acids, amino
acids, and intestinal glucose. While serum glucose also stimulates
insulin secretion by the pancreas, the effect of intraluminal glucose on
GIP and subsequent insulin secretion leads to increased concentrations
of insulin compared to parenteral glucose
,administration. Insulin promotes peripheral tissue uptake of glucose,
glycolysis, glycogen synthesis, protein synthesis, and fatty acid
synthesis, resulting in decreased glucose concentration in the serum.
Incorrect Answers: A, C, D, and E.
Gastrin (Choice A) is produced by G cells in the gastric antrum and
stimulates parietal cells within the gastric body to produce hydrochloric
acid. Gastric acid has no effect on serum glucose concentration.
Motilin (Choice C) is secreted by the small intestine and stimulates
intestinal peristalsis. Motilin receptors are targeted by erythromycin and
metoclopramide, used therapeutically in gastroparesis.
Secretin (Choice D) is produced by duodenal S cells. It promotes the
release of bicarbonate-rich pancreatic secretions and bile and inhibits
gastric acid production.
Somatostatin (Choice E) is a regulatory peptide secreted by D cells of
the pancreas and gastrointestinal mucosa that inhibits gastric acid and
pepsinogen secretion, gallbladder contraction, and insulin and glucagon
release. Somatostatin would have an indirect
effect on glucose through counterregulatory action of both insulin and
glucagon.
Educational Objective: Glucose-dependent insulinotropic peptide (GIP)
is secreted by K cells in the duodenum and jejunum, and it functions to
decrease gastric acid production and
⫸3
Exam Section 1: Item 3 of 50
National Board of Medical Examiners®
Comprehensive Basic Science Self-Assessment
,3. A 53-year-old man comes to the physician because of a 6-day history
of shortness of breath, cough, and pleuritic chest pain. His temperature is
38.9°C (102°F), and respirations are 35/min. Sputum is purulent and rust
colored. Physical examination shows
decreased breath sounds, and crackles are heard at the left base. A Gram
stain of sputum shows gram-positive diplococci. A chest x-ray shows
left-sided lobar consolidation. Which of the following anatomic
structures most likely allowed rapid spread of
organisms between alveoli to involve the entire left lobe in this patient?
A) Alveolar capillaries
B) Germinal centers
C) Lymphatic capillaries
D) Pores of Kohn
E) Vascular sinusoids Answer: D.
The pores of Kohn form connections between alveoli and are present in
normal lung tissue. They are composed, at least in part, of type Il
alveolar cells and allow for the passage of air, fluid, phagocytes, and in
the setting of pneumonia, bacteria between adjacent
alveoli. By allowing equilibration between adjacent alveoli, the pores of
Kohn aid in normal oxygenation and in the prevention of atelectasis.
However, infectious organisms and inflammation may also spread
between adjacent alveoli through these apertures.
Incorrect Answers: A, B, C, and E.
Alveolar capillaries (Choice A) surround each alveolus and are crucial
for gas exchange. However, they do not provide a direct connection
between adjacent alveoli, provided that the alveolar and capillary
endothelia remain intact.
, Germinal centers (Choice B) allow for the development of B
lymphocytes and are important in mounting an adaptive immune
response to pulmonary pathogens. They do not form connections
between alveoli.
Lymphatic capillaries (Choice C) allow for the drainage of interstitial
fluid from the lung parenchyma to the lymphatic ducts and eventually to
the heart. These passages do not form direct anastomoses between
adjacent alveoli.
Vascular sinusoids (Choice E) are present in hepatic tissue and create
anastomoses between the portal and systemic circulation, allowing for
the exchange of nutrients with hepatocytes. They are not present in
pulmonary tissue.
Educational Objective: The pores of Kohn form connections between
alveoli and are present in normal lung tissue. They allow for the passage
of air, fluid, phagocytes, and, in the setting of pneumonia, bacteria
between adjacent alveoli.
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⫸4
Exam Section 1: Item 4 of 50
