Pancreatic juice ________.

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.

Answer Explanation

c) pyloric sphincter

- Correct: During gastric emptying, chyme (partially digested food) is released from the stomach into the duodenum through the pyloric sphincter. The pyloric sphincter is a muscular valve located at the junction between the stomach and the duodenum. It regulates the passage of chyme from the stomach into the small intestine, allowing for controlled release and preventing backflow of intestinal contents into the stomach.

a) pyloric antrum

- Incorrect: The pyloric antrum is the lower portion of the stomach that leads into the pyloric canal. It is involved in mixing and churning food, but it does not regulate the release of chyme into the duodenum.

b) pyloric canal

- Incorrect: The pyloric canal is the narrow portion of the stomach that connects the pyloric antrum to the pyloric sphincter. It is involved in directing chyme toward the pyloric sphincter for release into the duodenum, but it is not the site of chyme release itself.

The esophageal hiatus is an opening in the diaphragm through which the esophagus passes as it descends from the thoracic cavity into the abdominal cavity. It is not directly involved in gastric emptying.

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.