Question 1

Which structural modification of the small intestine is primarily responsible for increasing the surface area for nutrient absorption by 600 times, and what is its approximate total surface area?

Accepted Answer

Microvilli; approximately 200 m$$^2$$

Question 2

During carbohydrate digestion in the small intestine, which enzyme is responsible for the final breakdown of disaccharides into monosaccharides, and how are glucose and galactose absorbed?

Accepted Answer

Brush border enzymes; absorbed via cotransport with Na$$^+$$

Question 3

A patient undergoing chemotherapy experiences nausea, vomiting, and diarrhea. Which cell type in the small intestine is most likely affected, and why?

Accepted Answer

Stem cells; because chemotherapy targets rapidly dividing cells

Question 4

Which of the following best describes the mechanism of protein absorption in the small intestine?

Accepted Answer

Amino acids are absorbed via cotransport with Na$$^+$$ across the apical membrane and exit via facilitated diffusion across the basolateral membrane

Question 5

Which process is primarily responsible for mixing and moving chyme toward the ileocecal valve after a meal in the small intestine?

Accepted Answer

Segmentation

Question 6

What is the primary function of the large intestine's bacterial flora?

Accepted Answer

Fermentation of indigestible carbohydrates and synthesis of vitamin K

Question 7

Which clinical condition is characterized by acute inflammation of the appendix due to blockage by feces, and what is a potential life-threatening complication?

Accepted Answer

Appendicitis; peritonitis

Question 8

Which vitamin requires intrinsic factor for absorption in the small intestine, and by what mechanism is it absorbed?

Accepted Answer

Vitamin B12; endocytosis

Question 9

In the process of lipid digestion and absorption, what is the role of bile salts, and how are chylomicrons transported after formation?

Accepted Answer

Bile salts emulsify fat globules; chylomicrons enter lymphatic lacteals

Question 10

Which structural feature is unique to the large intestine and is responsible for its segmented appearance?

Accepted Answer

Haustra

Question 11

A person with lactose intolerance lacks which enzyme, and what is the physiological consequence of consuming lactose?

Accepted Answer

Lactase; osmotic diarrhea and gas production

Question 12

Which hormone initiates peristalsis in the small intestine between meals, and what is the resulting pattern called?

Accepted Answer

Motilin; migrating motor complex (MMC)

Question 13

Which of the following best describes the absorption of water in the gastrointestinal tract?

Accepted Answer

95% of water is absorbed in the small intestine by osmosis

Question 14

Which cell type in the small intestine is responsible for secreting antimicrobial agents such as defensins and lysozyme?

Accepted Answer

Paneth cells

Question 15

Which process is triggered by distension of the rectum and involves both involuntary and voluntary control?

Accepted Answer

Defecation reflex

Question 16

Iron absorption in the small intestine is regulated by which protein, and how is iron transported in the blood when needed?

Accepted Answer

Ferritin; transported by transferrin

Question 17

Which of the following is a major function of the large intestine?

Accepted Answer

Propulsion of feces to the anus and defecation

Question 18

Which clinical condition is associated with a low-fiber diet, resulting in herniations of the mucosa in the colon?

Accepted Answer

Diverticulosis

Question 19

Which mechanism is used for the absorption of most polar molecules (such as glucose and amino acids) in the small intestine?

Accepted Answer

Active transport

Question 20

Which clinical condition is caused by an immune reaction to gluten, resulting in damage to intestinal villi and brush border?

Accepted Answer

Celiac disease

Digestion and Absorption in the Small and Large Intestine

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