Enteroendocrine cell

Enteroendocrine cells

Diagram of digestive hormones secreted by enteroendocrine cells.

Enteroendocrine cells are specialized cells found in the gastrointestinal tract and pancreas that release hormones in response to various stimuli. These cells play a crucial role in the regulation of digestion, metabolism, and appetite. They are part of the diffuse endocrine system and are distributed throughout the epithelium of the stomach, small intestine, and colon.

Types of enteroendocrine cells

Enteroendocrine cells are classified based on the hormones they secrete and their location within the gastrointestinal tract. Some of the major types include:

• G cells: Located in the stomach, these cells secrete gastrin, which stimulates gastric acid secretion.
• I cells: Found in the duodenum and jejunum, they release cholecystokinin (CCK), which stimulates gallbladder contraction and pancreatic enzyme secretion.
• S cells: Also located in the duodenum, these cells secrete secretin, which stimulates the pancreas to release bicarbonate to neutralize stomach acid.
• K cells: Found in the duodenum and jejunum, they produce gastric inhibitory peptide (GIP), which induces insulin secretion.
• L cells: Located in the ileum and colon, they secrete glucagon-like peptide-1 (GLP-1), which enhances insulin secretion and inhibits glucagon release.

Function

Enteroendocrine cells are integral to the endocrine system of the gut, often referred to as the "gut-brain axis." They sense nutrients and other stimuli in the gut lumen and respond by secreting hormones that regulate various physiological processes. These hormones can act locally on nearby cells or enter the bloodstream to exert systemic effects.

Regulation of digestion

Enteroendocrine cells modulate the digestive process by regulating the secretion of digestive enzymes, bile, and gastric acid. For example, CCK released by I cells stimulates the pancreas and gallbladder, aiding in the digestion of fats and proteins.

Appetite control

Hormones such as GLP-1 and peptide YY (PYY) are involved in signaling satiety to the central nervous system, thereby regulating food intake and body weight.

Glucose homeostasis

Enteroendocrine hormones like GIP and GLP-1 play a role in the regulation of blood glucose levels by enhancing insulin secretion in response to nutrient intake.

Clinical significance

Dysfunction of enteroendocrine cells can lead to various gastrointestinal disorders and metabolic diseases. For instance, impaired GLP-1 secretion is associated with type 2 diabetes mellitus. Understanding the role of these cells in health and disease is crucial for developing new therapeutic strategies.

Related pages

• Gastrointestinal tract
• Endocrine system
• Hormone
• Pancreas
• Metabolism