Question 1

Which of the following best describes paracellular transport of water in the gastrointestinal (GI) tract?

Accepted Answer

Water moves between cells through tight junctions in response to a solute concentration gradient.

Question 2

In the context of mass balance in the digestive system, which of the following is TRUE regarding the fate of water secreted into the GI tract?

Accepted Answer

Most water secreted into the GI tract is reabsorbed by the small and large intestines.

Question 3

Which of the following is a function of serous secretions from exocrine glands in the digestive system?

Accepted Answer

Providing watery solutions containing ions for enzymatic activity

Question 4

Which cell type is primarily responsible for producing mucous secretions in the digestive tract?

Accepted Answer

Goblet cells

Question 5

A selectively permeable membrane separates two compartments: A (low glucose) and B (high glucose). Water moves from A to B. Which principle explains this movement?

Accepted Answer

Osmosis due to a solute concentration gradient

Question 6

Which of the following equations best represents the osmotic movement of water across a membrane in the GI tract?

Accepted Answer

$$J_{water} = L_p (\Delta \pi)$$

Question 7

Which of the following is NOT a component typically secreted into the digestive tract?

Accepted Answer

DNA

Question 8

Which process allows ions to move across the epithelial membrane in the digestive system?

Accepted Answer

Membrane channels and paracellular transport

Question 9

Which structure in exocrine glands is responsible for the initial secretion of serous or mucous products?

Accepted Answer

Acinus/acini (acinar cells)

Question 10

If the concentration of glucose in compartment B is increased, what will happen to the rate of water movement from compartment A to B?

Accepted Answer

It will increase due to a higher osmotic gradient.

Question 11

Which of the following best explains why proteins are secreted by cells rather than by paracellular transport?

Accepted Answer

Proteins are too large to pass through tight junctions between cells.

Question 12

Which of the following is a plausible consequence if the tight junctions between GI epithelial cells become leaky?

Accepted Answer

Increased paracellular transport of water and ions

Question 13

Which of the following is TRUE regarding the mass balance of secretions in the digestive system?

Accepted Answer

The amount of water and ions secreted must be balanced by absorption and excretion.

Question 14

Which of the following best describes the role of acinar cells in exocrine gland secretion?

Accepted Answer

They secrete serous or mucous products into the gland lumen.

Question 15

Which of the following would most likely result from a defect in the membrane channels for ion transport in the GI tract?

Accepted Answer

Impaired secretion of ions into the lumen

Digestive System: Secretion – Mass Balance and Exocrine Gland Function

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