Nokea
Where are most digestive enzymes activated?
- A. stomach
- B. small intestine
- C. liver
- D. pancreas
Correct Answer: B
Rationale: The correct answer is B: small intestine. Digestive enzymes are activated in the small intestine to break down nutrients. Firstly, enzymes are secreted by the pancreas into the small intestine, where they act on carbohydrates, proteins, and fats. Secondly, bile from the liver helps in the digestion of fats. The stomach mainly secretes gastric juices for protein digestion, not enzymes for overall digestion. The liver produces bile, not digestive enzymes. The pancreas secretes various digestive enzymes, but they become activated in the small intestine.
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The stomach produces acids, which denature protein, and popsin that digests protein. The cell membranes of the epithelial cells lining the stomach contain protein. The protein in the epithelial cells are not denatured or digested because
- A. the membranes contain a different type of protein that resists denaturation and digestion.
- B. mucus coats the epithelium.
- C. cell membranes are destroyed but mitotic activity replaces cells with new ones every few hours.
- D. hormones produced by the endocrine cells protect the cell membranes and neutralize the acid pH.
Correct Answer: B
Rationale: The correct answer is B: mucus coats the epithelium. The mucus layer acts as a protective barrier that prevents the acid and pepsin from coming into direct contact with the epithelial cells. This physical barrier helps to shield the cell membranes from denaturation and digestion. Choice A is incorrect because the type of protein in the cell membranes does not determine their resistance to denaturation and digestion. Choice C is incorrect because cell membranes are not destroyed, and mitotic activity does not play a role in protecting the cell membranes. Choice D is incorrect because hormones do not directly protect the cell membranes from acid and pepsin; rather, it is the mucus layer that provides the necessary protection.
Fatty acids and glycerol are released when _____ are broken down by liver or muscle cells.
- A. micelles
- B. chylomicrons
- C. lacteals
- D. lipoproteins
Correct Answer: B
Rationale: The correct answer is B: chylomicrons. Chylomicrons are lipoprotein particles that transport dietary lipids (including fatty acids and glycerol) from the small intestine to the liver or muscle cells for metabolism. When chylomicrons reach the liver or muscles, lipoprotein lipase breaks them down, releasing fatty acids and glycerol for energy production or storage.
Now, let's analyze why the other choices are incorrect:
A: Micelles are small lipid droplets formed in the small intestine to aid in lipid digestion and absorption, but they do not release fatty acids and glycerol when broken down.
C: Lacteals are lymphatic vessels in the small intestine that absorb dietary fats, but they do not release fatty acids and glycerol.
D: Lipoproteins are involved in transporting lipids in the bloodstream but do not release fatty acids and glycerol when broken down.
Bacteria and other foreign material absorbed by the small intestine are destroyed by ______ cells found lining the hepatic sinusoids.
- A. Kupffer
- B. hepatic
- C. endothelial
- D. acinar
Correct Answer: A
Rationale: The correct answer is A: Kupffer cells. Kupffer cells are specialized macrophages found in the liver that play a crucial role in immune defense. They are responsible for destroying bacteria and foreign material absorbed by the small intestine as they pass through the hepatic sinusoids. Kupffer cells phagocytize these pathogens, preventing their entry into the bloodstream. The other choices, B: hepatic, C: endothelial, and D: acinar, do not have the specific function of destroying bacteria in the hepatic sinusoids. Hepatic cells are liver cells, endothelial cells line blood vessels, and acinar cells are found in exocrine glands.
Which method is preferred for immediate treatment of an acute episode of constipation?
- A. An enema
- B. Stool softeners
- C. Increased fluid
- D. Bulk-forming medication
Correct Answer: A
Rationale: An enema is often the preferred immediate treatment for acute constipation to relieve discomfort and promote bowel evacuation.
Regarding deglutition (swallowing):
- A. Pharyngeal phase is voluntary.
- B. Is controlled by a center in the medulla oblongata.
- C. Readily occurs with an open mouth.
- D. Buccal phase is accompanied by apnea.
Correct Answer: B
Rationale: The correct answer is B because swallowing is controlled by the swallowing center in the medulla oblongata. This center coordinates the complex sequence of muscle contractions involved in swallowing, ensuring food moves from the mouth to the esophagus without entering the airway. The pharyngeal phase is actually involuntary, not voluntary (Choice A). Swallowing usually occurs with a closed mouth, not an open one (Choice C). Additionally, the buccal phase is not accompanied by apnea; breathing typically continues during this phase (Choice D). Therefore, the correct answer is B due to the central control of swallowing in the medulla oblongata.