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 the following membranes covers the stomach?

A. falciform ligament

B. mesocolon

C. parietal peritoneum

D. visceral peritoneum

Answer Explanation

d) visceral peritoneum

- Correct: The visceral peritoneum covers the stomach. The peritoneum is a serous membrane that lines the abdominal cavity and covers most of the abdominal organs. The portion of the peritoneum that directly covers the surface of an organ is called the visceral peritoneum. In the case of the stomach, the visceral peritoneum covers its outer surface, providing a protective and lubricating layer.

a) falciform ligament

- Incorrect: The falciform ligament is a fold of peritoneum that attaches the liver to the anterior abdominal wall and diaphragm. It does not cover the stomach.

b) mesocolon

- Incorrect: The mesocolon is a fold of peritoneum that attaches the colon to the posterior abdominal wall. It does not cover the stomach.

c) parietal peritoneum

- Incorrect: The parietal peritoneum lines the abdominal cavity but does not cover individual organs. It forms the outer layer of the peritoneum and is not directly associated with covering the stomach.
Q #2: Which phase of deglutition involves contraction of the longitudinal muscle layer of the muscularis?

A. voluntary phase

B. buccal phase

C. pharyngeal phase

D. esophageal phase

Answer Explanation

a) voluntary phase

- Correct: The voluntary phase of deglutition (swallowing) involves the initial voluntary movement of food from the mouth into the pharynx. During this phase, the tongue pushes the food bolus backward toward the oropharynx. Contraction of the longitudinal muscle layer of the muscularis propels the food bolus into the pharynx, which is part of the voluntary control of swallowing.

b) buccal phase

- Incorrect: The buccal phase of deglutition involves the initial formation of the food bolus and its movement toward the oropharynx by the coordinated action of the tongue and muscles of the cheeks. It does not involve contraction of the longitudinal muscle layer of the muscularis.

c) pharyngeal phase

- Incorrect: The pharyngeal phase of deglutition is involuntary and occurs when the food bolus reaches the pharynx. It involves the sequential contraction of muscles in the pharyngeal wall to propel the food bolus downward toward the esophagus. The contraction of the longitudinal muscle layer of the muscularis is not a significant component of the pharyngeal phase.

d) esophageal phase

- Incorrect: The esophageal phase of deglutition involves the passage of the food bolus through the esophagus and into the stomach. Peristaltic waves of contraction and relaxation of the muscularis propels the food bolus along the length of the esophagus. The contraction of the longitudinal muscle layer of the muscularis primarily occurs during the voluntary phase of deglutition, not the esophageal phase.
Q #3: Where are most fat-digesting enzymes produced?

A. small intestine

B. gallbladder

C. liver

D. pancreas

Answer Explanation

d) pancreas

- Correct: Most fat-digesting enzymes, such as pancreatic lipase, are produced in the pancreas. Pancreatic lipase is secreted by the pancreas into the small intestine, specifically the duodenum, where it plays a crucial role in the digestion of dietary fats. Additionally, other enzymes involved in fat digestion, such as pancreatic colipase and phospholipase, are also produced by the pancreas.

a) small intestine

- Incorrect: While some fat-digesting enzymes are present in the small intestine, the majority of these enzymes are produced by the pancreas and delivered to the small intestine via the pancreatic duct.

b) gallbladder

- Incorrect: The gallbladder stores and concentrates bile produced by the liver, but it does not produce fat-digesting enzymes. Bile stored in the gallbladder contains bile salts, which aid in the emulsification and digestion of fats, but they are not enzymes themselves.

c) liver

- Incorrect: The liver produces bile, which contains bile salts that aid in fat digestion by emulsifying large fat globules into smaller droplets, but it does not produce fat-digesting enzymes. The liver also plays a role in lipid metabolism and the synthesis of lipoproteins but does not produce enzymes directly involved in fat digestion.

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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 the following membranes covers the stomach?

Answer Explanation

Q #2: Which phase of deglutition involves contraction of the longitudinal muscle layer of the muscularis?

Answer Explanation

Q #3: Where are most fat-digesting enzymes produced?

Answer Explanation

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