Which of the following organs has 3 layers of smooth muscle in its muscularis externa?

A. small intestine

B. esophagus

C. stomach

D. large intestine

Answer Explanation:

C. stomach

- Correct: The stomach has three layers of smooth muscle in its muscularis externa, which is the muscular layer of the gastrointestinal tract responsible for peristalsis and mixing of food. These muscle layers are arranged in longitudinal, circular, and oblique orientations, allowing for the mechanical processing of ingested food and the propulsion of food through the digestive tract. This muscular arrangement contributes to the stomach's ability to churn and mix food with gastric juices during digestion.

A. small intestine

- Incorrect: While the small intestine does have smooth muscle in its muscularis externa, it typically has two layers of smooth muscle: an inner circular layer and an outer longitudinal layer.

B. esophagus

- Incorrect: The esophagus also has smooth muscle in its muscularis externa, but it typically has two layers of smooth muscle: an inner circular layer and an outer longitudinal layer.

D. large intestine

- Incorrect: The large intestine, like the small intestine, typically has two layers of smooth muscle in its muscularis externa: an inner circular layer and an outer longitudinal layer.

Therefore, the Correct Answer is C.

Q #1: Which of these is involved in the chemical digestion of protein?

A. pancreatic amylase

B. trypsin

C. sucrase

D. pancreatic nuclease

Answer Explanation

b) trypsin

- Correct: Trypsin is an enzyme involved in the chemical digestion of protein. It is secreted as trypsinogen by the pancreas and activated to its active form, trypsin, by enterokinase in the duodenum. Trypsin breaks down proteins into smaller peptides by cleaving peptide bonds between specific amino acids.

a) pancreatic amylase

- Incorrect: Pancreatic amylase is an enzyme involved in the digestion of carbohydrates (starches). It breaks down starch molecules into maltose and other simpler sugars.

c) sucrase

- Incorrect: Sucrase is an enzyme involved in the digestion of disaccharide sugars, specifically sucrose. It catalyzes the hydrolysis of sucrose into its constituent monosaccharides, glucose, and fructose.

d) pancreatic nuclease

- Incorrect: Pancreatic nuclease is an enzyme involved in the digestion of nucleic acids (DNA and RNA). It breaks down nucleic acid molecules into their component nucleotides.
Q #2: Which of these organs is not considered an accessory digestive structure?

A. mouth

B. salivary glands

C. pancreas

D. liver

Answer Explanation

a) mouth

- Correct: The mouth is not considered an accessory digestive structure; it is an integral part of the alimentary canal (digestive tract). The mouth is where the process of digestion begins, as food is ingested, chewed, and mixed with saliva. Saliva, produced by the salivary glands, contains enzymes (such as amylase) that initiate the breakdown of carbohydrates. Once food is sufficiently broken down in the mouth, it is formed into a bolus and swallowed, entering the esophagus and continuing its journey through the digestive system.

b) salivary glands

- Incorrect: Salivary glands are accessory digestive structures that secrete saliva into the mouth. Saliva contains enzymes and lubricants that aid in the mechanical and chemical digestion of food.

c) pancreas

- Incorrect: The pancreas is an accessory digestive structure that plays a crucial role in digestion by producing and secreting digestive enzymes into the small intestine. These enzymes aid in the breakdown of carbohydrates, proteins, and fats.

d) liver

- Incorrect: The liver is also an accessory digestive structure that contributes to digestion by producing bile, which is stored in the gallbladder and released into the small intestine to aid in the emulsification and digestion of fats. Additionally, the liver plays a role in processing nutrients absorbed from the small intestine and regulating glucose metabolism.
Q #3: Which of these cells secrete hormones?

A. parietal cells

B. mucous neck cells

C. enteroendocrine cells

D. chief cells

Answer Explanation

c) enteroendocrine cells

- Correct: Enteroendocrine cells are specialized cells located in the epithelium of the gastrointestinal tract that secrete hormones. These hormones play various roles in the regulation of digestion, nutrient absorption, and other physiological processes. Examples of hormones secreted by enteroendocrine cells include gastrin, secretin, cholecystokinin (CCK), and ghrelin.

a) parietal cells

- Incorrect: Parietal cells are found in the gastric glands of the stomach and secrete hydrochloric acid (HCl) and intrinsic factor, but they do not secrete hormones.

b) mucous neck cells

- Incorrect: Mucous neck cells are found in the gastric glands of the stomach and secrete mucus, which helps protect the stomach lining from the acidic environment, but they do not secrete hormones.

d) chief cells

- Incorrect: Chief cells are found in the gastric glands of the stomach and secrete pepsinogen, the precursor to the enzyme pepsin, which plays a role in protein digestion. Chief cells do not secrete hormones.

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Which of the following organs has 3 layers of smooth muscle in its muscularis externa?

More Questions on TEAS 7 Science

Q #1: Which of these is involved in the chemical digestion of protein?

Answer Explanation

Q #2: Which of these organs is not considered an accessory digestive structure?

Answer Explanation

Q #3: Which of these cells secrete hormones?

Answer Explanation

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