193. The Intestinal Mucosal Barrier & Hyperpermeability | Highlighting the Role of Zinc in Supporting Intestinal Barrier Function
In this episode, we detail the structure and function of the intestinal mucosal barrier, highlighting key roles that zinc plays in supporting various aspects of mucosal barrier integrity. We detail key anatomical features, including the mucus layer, epithelial cells, and tight junctions, before discussing zinc’s physiological roles, its relationship with copper, and factors that can affect zinc levels. The discussion further details mechanistic features of zinc absorption as well as specialized forms such as zinc carnosine.
Topics:
1. Introduction
- Overview of intestinal hyperpermeability and intestinal barrier function
- Highlighting the role of zinc
2. Intestinal Barrier Anatomy
- Four major layers: mucosa, submucosa, muscularis externa, serosa
- Mucosa subdivisions; focus on epithelium
3. The Mucus Layer
- Location over the epithelial surface
- Composition: mucin-rich, secreted by goblet cells
- Goblet cell mucin storage and expansion upon hydration
- Functions: trapping pathogens, lubricating epithelium, housing molecules including secretory IgA
- Small intestine mucus
- Large intestine mucus
4. The Intestinal Epithelium
- Monolayer of epithelial cells: enterocytes, goblet cells, and more
- Tight junctions, paracellular transport
- Continuous epithelial renewal
5. Introduction to Zinc
- Zinc as a trace mineral required in minute quantities for numerous physiological processes
- Second most abundant trace mineral after iron; majority stored in muscle and bone
- Maintaining plasma and intracellular zinc concentrations within narrow range
- Both deficiency and excess can disrupt biochemical processes
6. Zinc and Copper
- Zinc and copper as closely interconnected minerals
- Zinc, copper, and metallothionein binding in enterocytes
- Both high and low zinc can disrupt zinc-copper balance
- Metallothionein as a cysteine-rich metal-binding protein
7. Factors Affecting Zinc Levels
- Multifactorial
- Possible signs of low zinc status
8. Zinc Absorption
- Dietary sources
- Primary absorption in small intestine
- In the stomach: HCl and pepsin denature proteins and cleave peptide bonds, releasing zinc from protein complexes
- Dietary zinc often bound within tertiary protein structure
- Specialized transporters
9. Zinc’s Role in the Intestinal Barrier
- Zinc and tight junction proteins
- Zinc and Intestinal Epithelial Cells
- Zinc and the mucus layer
10. Broader Context of Zinc in Physiology
11. Zinc Carnosine
- Molecular complex of zinc and carnosine
- L-carnosine composed of beta-alanine and L-histidine
- Gastrointestinal context
12. Conclusion
- Multifactorial and multi-system.
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