Formative Quiz 1

Question 1

A biopsy specimen is sent to a pathologist for diagnosis. The origin of this tissue is not clear other than knowing that it is from the gastrointestinal tract. The pathologist notices the presence of simple columnar epithelium, epithelial villi and crypts, and glands in the submucosa. How can she use these characteristics to determine the origin of this tissue?

• It helps her to distinguish the esophagus from the stomach.
• It helps her to distinguish the esophagus from the jejunum/ileum.
• It helps her to distinguish the duodenum from the jejunum/ileum.
• It helps her to distinguish the duodenum from the colon.
• It helps her to distinguish the colon from the jejunum/ileum.

Answer 1

It helps her to distinguish the duodenum from the jejunum/ileum.

c. is correct. Both the duodenum and jejunum/ileum have villi and crypts, but only the duodenum has submucosal glands.

Question 2

What is the biggest distinction between the esophagus and stomach?

Answer 2

greatest distinction between esophagus and stomach is in the epithelium; stratified squamous vs. glandular simple columnar respectively

Question 3

Does the colon have villi?

Answer 3

NO

Question 4

Are gut flora necessary for proper immune development?

Answer 4

Hell yeah

Question 5

Which one of the following mechanisms best describes the regulation of secretion from the predominant cells in the accompanying image?

• Phosphorylation by kinases of the H+K+-ATPase (proton pump) which initiates secretion and dephosphorylation by phosphatases which returns the cell to the basal state.
• Exocytosis which initiates secretion and endocytosis which returns the cell to the basal state.
• Binding of CCK (cholecystokinin) to the high affinity CCKB receptor on the parietal cell.
• Binding of histamine to the H2 receptor on the parietal cell which activates GQ and leads to elevated cytosolic Ca2+.
• Binding of somatostatin to its receptor on the parietal cell which activates GQ and leads to elevated cytosolic cAMP.

Answer 5

Exocytosis which initiates secretion and endocytosis which returns the cell to the basal state.

Stimulation of the parietal cell causes tubulovesicles to be exocytosed, thus inserting the proton pump (H+K+-ATPase) into the apical plasma membrane (intracellular canaliculus); when the stimulus is removed, the proton pump is endocytosed, reforming the tubulovesicles and ending acid secretion

Question 6

Individuals with chronic gastric reflux into the esophagus may develop a metaplasia called Barrett’s esophagus, as illustrated in this image (stained using Alcian blue which stains mucins light blue). This metaplasia is believed to be the precursor to esophageal adenocarcinoma making it clinically important.
Which one of the following statements best describes why this process may happen?

This intestine-like metaplastic epithelium better withstands exposure to gastric secretions.

Exposure to gastric secretions causes ulceration which is evident in this image.

Chronic gastric reflux induces mucin gene expression in stratified squamous epithelium.

Metaplasia always happens as a simple columnar epithelium.

This gastric-like metaplastic epithelium better withstands exposure to gastric secretions.

Answer 6

This intestine-like metaplastic epithelium better withstands exposure to gastric secretions.

Intestine-like epithelium produces mucus from goblet cell (Alcian blue staining) and secretes bicarbonate ion, both of which protect against gastric secretions

Question 7

A 60-year-old man was diagnosed with a direct inguinal hernia 10 years ago that now needs surgical repair. A 3rd year medical student is asked to review the anatomy of the inguinal region before the surgery. Among the structures that are all associated with the inguinal region, which one of the following forms the superficial ring of the inguinal canal?

Answer 7

External inguinal canal

Question 8

A 50-year-old man has had abdominal pain for many years. He is diagnosed by upper GI endoscopy (EGD) with a peptic ulcer. Referred pain produced by gastric or peptic ulcers is usually located in the epigastric region of the anterior abdominal wall. The body surface dermatome for the epigastric region is innervated by spinal nerves (somatic nerves) T7 and T8. The pain of the stomach and the duodenum is transmitted by autonomic nerve fibers (visceral nerves) to the same level of spinal cord (T7 and T8). Which one of the following nerve structures most likely transmits the pain sensation from the stomach and the duodenum to the central nervous system?

Vagus nerve

Greater splanchnic nerve

Lesser splanchnic nerve

Least splanchnic nerve

Esophageal plexus

Sympathetic trunk

Answer 8

The greater splanchnic nerve is comprised of preganglionic sympathetic fibers from T5 through T9. These fibers synapse at the celiac ganglion and the post-ganglionic fibers travel to the foregut organs including stomach and duodenum. Pain from the foregut organs is transmitted by the greater splanchnic nerve to the dorsal root ganglia (DRG) of T5-T9.

Question 9

A 55-year-old man has a history of hepatitis for the past 15 years. Recently, he developed a bloated abdomen and had reduced liver function. Liver cirrhosis and hepatic portal hypertension are diagnosed. Which one of the following symptoms is associated most closely with the inferior mesenteric vein, which is mainly affected in this case?

Lower esophageal varices and possible bleeding

Caput medusa in the anterior abdominal wall

Blood in the feces

Swelling of the lower limbs

Answer 9

Blood in the feces

The inferior mesenteric vein anastomoses with the venous branches off the internal and external iliac veins around the lower rectum and anal canal. Increased pressure in the inferior mesenteric vein causes venous blood flow through these anastomoses and resulting in venous varices in the anal canal. When the engorged veins in the anal canal are damaged by feces, blood appears in the feces.

Question 10

A laboratory investigator has been studying a rare new animal species and has isolated a previously uncharacterized amino acid which appears to be related to the known amino acid, tryptophan but has a higher molecular weight. In order to characterize the metabolism of this new amino acid, the structure is synthesized using radioactive carbon, C14. After injecting the labeled amino acid into an animal, a short time later it is determined that the C14 label is found predominantly in the form of acetyl CoA and pyruvate. The metabolic class of this new amino acid needs to be characterized. Which one of the following best describes its classification?

Exclusively glucogenic

Exclusively ketogenic

Both glucogenic and ketogenic

Not possible to determine its classification

Answer 10

Both glucogenic and ketogenic

Question 11

Amino acids that form Acetyl CoA are glucogenic or ketogenic?

Answer 11

Ketogenic

Question 12

Amino acids that form pyruvate are gluconeogenic or ketogenic?

Answer 12

Gluconeogenic

Question 13

“Foramen of Winslow” is an anatomical structure that allows fluid to flow from one abdominal compartment to another. Using the following diagram please answer how fluid drains through the foramen.

From the space indicated by letter F to the rest of the abdominal space shaded in pink.

From the space shaded in blue to the rest of the abdominal space shaded in pink.

From the space shaded in pink to the abdominal space shaded in blue.

From stomach to duodenum.

From the space indicated by letter F to the rest of the abdominal space shaded in blue.

Answer 13

From the space shaded in blue to the rest of the abdominal space shaded in pink.

Foramen of Winslow, also called omental foramen or epiploic foramen, functions to allow fluid flow from the lesser sac (shaded in blue in the diagram) to the greater sac (shaded in pink). It is the only passage of fluid flow between these two abdominal compartments.

Question 14

Select the letter that points to a midgut organ that passes over IVC, vertebral column, and aorta at about L3 level.

Answer 14

G

A midgut organ that passes over IVC, vertebral column, and aorta at about L3 level is the 3rd part of duodenum which is also a retroperitoneal organ.

Question 15

Select the letter that points to a foregut organ and its location is retroperitoneal immediately posterior to the lesser sac.

Answer 15

E

A foregut organ and its location is retroperitoneal posterior to the lesser sac is the pancreas.

Question 16

A 25-year-old healthy man has begun an exercise program and has started to run on a treadmill. He has set the treadmill to a very fast pace. As his physical activity continues for several minutes his heart rate would be expected to increase. The levels of which one of the following amino acids would be expected to increase significantly in his blood?

aspartic acid

citric acid

lactic acid

pyruvic acid

uric acid

Answer 16

Lactic Acid

Rationale: fast pace exercise increases glucose metabolism, which involves both glycolysis and citric acid cycle. When the rate of glycolysis exceeds the amount of oxygen supply, pyruvate is utilized for lactic acid production.

Question 17

A healthy, adult woman traveling in Europe develops an acute urinary tract infection. A correct diagnosis of the infection is made and the patient was started on a high dose of a sulfa-based antimicrobial. The patient develops severe hemolytic anemia and is hospitalized. The antimicrobial is withdrawn and an unrelated antimicrobial is given; the patient improves and is discharged. A family history indicates that several first-degree relatives had also experienced episodes of hemolysis under other circumstances including the use of anti-malarial drugs and after eating certain foods.
A defect in which one of the following enzymes would be consistent with the symptoms seen in this individual?

Fructose 1,6-bisphosphate aldolase

Glucose 6-phosphate dehydrogenase

Pyruvate dehydrogenase

Alpha ketoglutarate dehydrogenase

Pyruvate carboxylase

Answer 17

Glucose 6-phosphate dehydrogenase

The answer is B. Glucose-6-phosphate dehydrogenase deficiency (G6PD deficiency) also known as favism (after the fava bean) is an X-linked recessive genetic condition that predisposes to hemolysis in response to a number of triggers, such as certain foods, illness, or medication.

Question 18

A 50-year-old woman with metabolic syndrome is motivated to make changes to her current diet and lifestyle in order to avoid the increased risk for type II diabetes. She has decided to make dietary changes and choose carbohydrates carefully according to the glycemic index. Which one of the following is true regarding the glycemic index?

Glycemic index is used to measure blood glucose levels for diabetic patients.

Glycemic index refers to how much sugar needs to be incorporated in cooking.

Glycemic index is not related to HDL cholesterol.

The ripeness of produce or fruits affects glycemic index

Answer 18

The ripeness of produce or fruits affects glycemic index

A measure of the ability of a food to raise the level of blood sugar is defined as “Glycemic Index”. Ripened produce or fruits have higher glycemic index. High glycemic index foods raise blood glucose rapidly and have been linked to hyperinsulinism, inflammation, low HDL cholesterol, obesity, type 2 diabetes, and cardiovascular disease.

Question 19

A newborn male child develops severe episodes of vomiting, seizures and while the child survives, it exhibits a variety of neurological deficits. The infant’s urine is observed to have a sweet smell, similar to maple syrup and lab tests confirm high levels of excreted organic acids related to amino acid metabolism.

Branched chain ketoacid dehydrogenase

Phenylalanine hydroxylase

D-amino acid oxidase

Homogentistic acid oxidase

Tyrosinase

Answer 19

Branched chain ketoacid dehydrogenase

Branched chain ketoacid dehydrogenase’ primary function in mammals is to catalyze an irreversible step in the catabolism of branched-chain amino acids namely L-isoleucine, L-valine, and L-leucine and their derivatives. A deficiency of the enzyme lend a sweet smell to bodily excretions (such as ear wax and urine), leading to a pathology known as maple syrup urine disease.

Question 20

The apical (brush border) membrane of the enterocyte has two monosaccharide transporters, GLUT5 (facilitated diffusion) and SGLT1 (secondary active). SGLT1 is of greater importance for monosaccharide absorption when which one of the following is ingested?

French fries

Sugar-free diet cola

Cola made with high-fructose corn syrup

Cola made with pure glucose

New York strip steak

Answer 20

French fries

French fries have a high concentration of starch, which is digested into monosaccharides. Absorption of the monosaccharides will require the secondary active process mediated by SGLT1 to efficiently absorb the monosaccarides.

Question 21

The accompanying transmission electron micrograph is from the duodenum of a rodent after a fat-rich meal. Which one of the following best describes the numerous small round grey structures in the apical cytoplasm stained with osmium?

re-esterified triglycerides in the smooth endoplasmic reticulum.

chylomicrons in the Golgi apparatus

apolipoproteins in the rough endoplasmic reticulum.

mitochondria.

peroxisomes.

Answer 21

re-esterified triglycerides in the smooth endoplasmic reticulum.

Question 22

Following the ingestion of a meal, what mechanism accounts for bicarbonate secretion by the pancreatic duct cells?

S cells in the duodenum produce secretin which acts as a hormone and stimulates duct cells

I cells in the duodenum produce CCK which acts on nerve receptors that send signals via the vagus to the CNS and back to the pancreatic duct cells

M cells in the ileum produce motilin that acts on the pancreatic duct cells

Enterochromafin cells that produce serotonin that stimulates pancreatic duct cells

PP cells in the pancreas produce pancreatic polypeptide to stimulate pancreatic duct cells

Answer 22

S cells in the duodenum produce secretin which acts as a hormone and stimulates duct cells

Question 23

A 22-year-old man with cystic fibrosis presents with pancreatic insufficiency. What is the main enzyme that would be affected in regard to the ability of this patient to hydrolyze triglycerides?

phospholipase A2

cholesterol esterase

lipase

amylase

co-lipase

Answer 23

Correct answer = C. Fat malabsorption is a hallmark of cystic fibrosis. As the lipid mixed micelles are formed from fat in the intestinal lumen, the initial stages of lipid digestion occur at the mixed micelle interface with the luminal fluid. The major lipid component of the micelles are triglycerides. The bulk of the digestion is carried out by lipase. Lipase hydrolyzes all remaining triglycerides that enter from stomach to yield free fatty acids and 2-monogyceride. Co-lipase is a co-factor required for activation of lipase, but has no intrinsic digestion activity. Phospholipase A2 digests glycerophospholipids which are not the major lipid of digestion. Cholesterol esterase is limited to digestion of cholesterol esters and not triglycerides.

Question 24

Match the answers below to the labels on this transmission electron micrograph.

Barrier to ions and macromolecules

Glycoproteins

Barrier to microbes

Microvilli

Location of enterokinase

Actin microfilaments

Terminal web

Cytoskeleton

Location of disaccharidases

Answer 24

Barrier to ions and macromolecules - e

Glycoproteins - f

Barrier to microbes - f

Microvilli - a

Location of enterokinase - a

Actin microfilaments - d

Terminal web - d

Cytoskeleton - d

Location of disaccharidases - a