Question 1

The flow of bile from the liver and juices from the exocrine pancreas converge at what structure?

Accepted Answer

The ampulla of Vater, also known as the hepatopancreatic ampulla, is where the bile duct and pancreatic duct converge and empty their contents into the duodenum, facilitating the digestion process.

Question 2

What is the functional unit of the liver?

Accepted Answer

The functional unit of the liver is the lobule, which is a hexagonal structure consisting of hepatocytes arranged around a central vein.

Question 3

What enzyme activates procarboxypeptidase?

Accepted Answer

Trypsin activates procarboxypeptidase by converting it into its active form, carboxypeptidase. This process is part of protein digestion in the small intestine.

Question 4

The absorption of glucose involves _________across the apical membrane and   _________across the basolateral membrane.

Accepted Answer

The absorption of glucose in the small intestine involves secondary active transport across the apical membrane (via the SGLT protein, which co-transports glucose with sodium ions) and facilitated diffusion across the basolateral membrane (via the GLUT protein), allowing glucose to move into the bloodstream.

Question 5

Which of the following is NOT one of the hormone -related functions of the liver?

Accepted Answer

The liver is involved in hormone modification, secretion of hormone-binding proteins, hormone degradation, and hormone synthesis, but it does not store hormones.

Question 6

What degradation by -product of hemoglobin is removed from the blood by the liver, conjugated, and then secreted into the bile?

Accepted Answer

Bilirubin is the degradation by-product of hemoglobin that is removed from the blood by the liver, conjugated, and then secreted into the bile.

Question 7

Where are enzymes that breakdown disaccharides located?

Accepted Answer

Enzymes that break down disaccharides are located on the apical membrane of enterocytes, which are cells lining the small intestine. This positioning allows for the direct digestion of disaccharides as they come into contact with the intestinal lining, facilitating their breakdown into monosaccharides for absorption.

Question 8

The absorption of fructose across the apical membrane of the lumenal epithelial cells occurs through what process?

Accepted Answer

Fructose is absorbed across the apical membrane of the lumenal epithelial cells through facilitated diffusion, utilizing transport proteins but not requiring energy directly.

Question 9

Which of the following is NOT one of the functions of the liver?

Accepted Answer

The liver does not secrete enzymes for digestion; this function is primarily associated with the pancreas and the glands in the stomach and small intestine. The liver's main roles include detoxification, protein synthesis (including albumin), and bile production, but not the secretion of digestive enzymes.

Question 10

Which of the following is NOT one of the wastes eliminated by the liver in bile?

Accepted Answer

Urea is not eliminated by the liver in bile; it is a waste product of protein metabolism that is primarily excreted by the kidneys in urine.

Question 11

One side of a hepatocyte faces the blood while the other faces what?

Accepted Answer

Hepatocytes are liver cells that have one side facing the blood through the sinusoid and the other side facing the bile canaliculi, which are small ducts that collect bile produced by the hepatocytes.

Question 12

The enzyme amylase is able to cleave glycogen and starch into

Accepted Answer

Amylase breaks down starch and glycogen into smaller sugar units, primarily disaccharides (like maltose) and limit dextrins, not exclusively into monosaccharides.

Question 13

The digestion of proteins begins in the______with the activation of the zymogen ______

Accepted Answer

The digestion of proteins begins in the stomach with the activation of the zymogen pepsinogen into pepsin, which starts breaking down proteins into smaller peptides.

Question 14

Which of the following is NOT an enzyme that acts on the products of amylase digestion of glycogen and starch?

Accepted Answer

Galactase is an enzyme that acts on galactose, not on the products of amylase digestion of glycogen and starch.

Question 15

Which of the following secretes lipase?

Accepted Answer

The answer of Which of the following secretes lipase?
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Question 16

Proteolytic enzymes secreted in pancreatic juice are stored in secretory cells of the pancreas as

Accepted Answer

Proteolytic enzymes secreted in pancreatic juice are stored in secretory cells of the pancreas as zymogens, which are inactive enzyme precursors. This prevents the enzymes from digesting the pancreas itself.

Question 17

What are Kupffer cells?

Accepted Answer

Kupffer cells are specialized macrophages located in the liver, responsible for removing bacteria and worn-out cells from the blood.

Question 18

What are liver sinusoids?

Accepted Answer

Liver sinusoids are specialized blood-filled channels that facilitate the exchange of materials between the blood and hepatocytes, the liver's primary cells. They are not pathways for bile exit, bile-filled cavities, sites of bile synthesis, or air-filled cavities.

Question 19

In order to convert amino acids to gluconeogenic precursors, their ammonium ion must be removed in the liver, which is then converted to what substance, thereby making it water soluble enough to be excreted by the kidneys?

Accepted Answer

The ammonium ion from amino acids is converted to urea in the liver through the urea cycle. Urea is water-soluble and can be excreted by the kidneys, making it the primary vehicle for removing excess nitrogen from the body.

Question 20

What enzyme is responsible for cleavage of the amino acid at the amine portion of the peptide fragment?

Accepted Answer

Aminopeptidase is responsible for cleaving peptides at the amino (N-terminal) end, removing one amino acid at a time.

Quiz 20: The Gastrointestinal System