The hormone secretin and pancreozymin are secreted by?

BSF Staff Nurse - 2015

Applied Physiology

Easy

Appeared in: BSF Staff Nurse - 2015

Explanation

The duodenum is the primary site for the secretion of both secretin and pancreozymin (also known as cholecystokinin or CCK).
Secretin is released from S-cells in the duodenal mucosa in response to acidic chyme arriving from the stomach.
Pancreozymin (CCK) is released from I-cells, which are most concentrated in the duodenal and upper jejunal mucosa, in response to the presence of fats and proteins.
These hormones are crucial for initiating the intestinal phase of digestion by signaling the pancreas and gallbladder.

Option B: While the jejunum does contain some cells that secrete these hormones (particularly CCK), the highest concentration of these endocrine cells and the primary site of release is the duodenum.
Option C: The appendix is a small, finger-like pouch attached to the large intestine. Its primary function is believed to be related to the immune system (as a storehouse for good gut bacteria), not hormone secretion for digestion.
Option D: The liver is a large, vital organ with many functions, including producing bile, detoxifying blood, and metabolizing nutrients. However, it does not secrete the hormones secretin or pancreozymin.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Secretion sites of major gastrointestinal hormones as background academic context rather than a clinical decision trigger.
The secretin stimulation test is a medical procedure used to assess pancreatic function. It helps diagnose conditions like chronic pancreatitis and gastrinomas (Zollinger-Ellison syndrome) by measuring the pancreas's response to secretin.
Understanding the function of these hormones is crucial for managing digestive disorders. For example, impaired CCK signaling can lead to poor fat digestion and gallstone formation (biliary sludge).
What if? If a patient had a tumor in the duodenum that overproduced CCK (a rare CCKoma), they would likely present with diarrhea, weight loss, and abdominal pain due to the constant, excessive stimulation of the pancreas and gallbladder.

How to Approach the Question

First, identify the key terms in the question: 'secretin,' 'pancreozymin,' and 'secreted by.'
Recognize that these are major hormones involved in the digestive process.
Consider the function of each organ listed in the options in the context of digestion.
Recall that the duodenum is the first part of the small intestine where acidic chyme from the stomach is processed.
Logically deduce that the hormones responsible for signaling the pancreas and gallbladder to aid in this initial stage of intestinal digestion must be released from the duodenum.
This eliminates the jejunum (primarily for absorption), appendix (immune function), and liver (bile production, not hormone secretion of this type).

Concept Tested & Keywords

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