Question 1

Which layer of the gastrointestinal (GI) tract is primarily responsible for absorption of nutrients, and what are its three sublayers?

Accepted Answer

Mucosa; epithelium, lamina propria, muscularis mucosae

Question 2

During the process of swallowing, which phase involves the elevation of the soft palate and uvula to block the nasopharynx, and what is the primary purpose of this action?

Accepted Answer

Pharyngeal phase; prevents food from entering the nasal cavity

Question 3

Which accessory organ produces bile, and what is the primary function of bile in digestion?

Accepted Answer

Liver; emulsifies fats to increase surface area for enzymatic digestion

Question 4

What is the function of the muscularis externa in the GI tract, and which two types of muscle layers does it contain?

Accepted Answer

Motility; inner circular and outer longitudinal layers

Question 5

Which hormone is released from the stomach and stimulates both gastric secretions and motility?

Accepted Answer

Gastrin

Question 6

A patient presents with grey-white stool and difficulty digesting fats. Which digestive secretion is most likely deficient, and what is the consequence of this deficiency?

Accepted Answer

Bile; inability to emulsify fats and excrete bilirubin

Question 7

Which equation best represents the formation of hydrochloric acid (HCl) in the parietal cells of the stomach?

Accepted Answer

$$ \mathrm{H^+} + \mathrm{Cl^-} \rightarrow \mathrm{HCl} $$

Question 8

Which structure in the small intestine is responsible for absorbing large lipids and lipid-soluble vitamins, and where do these nutrients go after absorption?

Accepted Answer

Lacteal; nutrients enter the lymphatic system

Question 9

Which enzyme is responsible for the initial breakdown of starch in the oral cavity, and why does its activity cease in the stomach?

Accepted Answer

Salivary amylase; inactivated by low pH in the stomach

Question 10

Which process in the GI tract involves alternating contraction and relaxation of circular muscle to mix contents, and how does it differ from peristalsis?

Accepted Answer

Segmentation; mixes contents without propelling them forward

Question 11

Which of the following best describes the role of brush border enzymes in the small intestine?

Accepted Answer

Complete the chemical digestion of carbohydrates and peptides

Question 12

A patient with chronic reflux esophagitis is at increased risk for which pathological change in the esophageal epithelium?

Accepted Answer

Transition from stratified squamous to columnar secretory epithelium

Question 13

Which equation represents the conversion of pepsinogen to pepsin in the stomach?

Accepted Answer

$$ 	ext{Pepsinogen} + 	ext{HCl} ightarrow 	ext{Pepsin} $$

Question 14

Which hormone is released in response to fatty chyme in the small intestine and stimulates the release of bile and pancreatic juice?

Accepted Answer

Cholecystokinin (CCK)

Question 15

Which anatomical feature of the small intestine increases surface area for absorption and acts as 'speed bumps' to slow movement of chyme?

Accepted Answer

Circular folds

Question 16

Which equation best represents the breakdown of triglycerides by pancreatic lipase in the small intestine?

Accepted Answer

$$ 	ext{Triglyceride} + 	ext{Pancreatic lipase} ightarrow 	ext{Monoglyceride} + 2 	ext{Fatty acids} $$

Question 17

Which structure in the large intestine is responsible for the manufacture of certain vitamins, and what is the primary vitamin produced?

Accepted Answer

Indigenous microbiota; vitamin K

Question 18

Which process is initiated by the filling of the rectum and involves increased parasympathetic output to the sigmoid colon and rectum?

Accepted Answer

Defecation reflex

Question 19

Which equation best represents the breakdown of nucleic acids by pancreatic nucleases in the small intestine?

Accepted Answer

$$ 	ext{Nucleic acid} + 	ext{Nuclease} ightarrow 	ext{Nucleotides} $$

Digestive System: Structure, Function, and Processes

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