| | Diet & Nutrition | Nutrition
Intestinal Nutrient Absorption: Mechanisms & Processes
Nutrients cross the intestinal epithelium via distinct transport mechanisms tailored to molecular properties:
Transport Pathways
- Simple Diffusion: Small lipophilic molecules (vitamins A, D, E, K) move down concentration gradients without energy or carriers.
- Facilitated Diffusion: Carrier‑mediated (GLUT2, GLUT5, etc.) for water‑soluble nutrients (glucose, fructose, amino acids, vitamin C, B12). Saturable, no ATP.
- Active Transport: Against gradient, ATP‑dependent. Examples: SGLT1 (glucose/galactose), PepT1 (dipeptides), DMT1 (iron), Ca²⁺‑ATPase (calcium).
- Endocytosis: Engulfment of large particles (chylomicrons, some proteins) into vesicles; transcytosis across enterocyte.
Post‑Absorptive Fate
Absorbed nutrients enter capillaries (water‑soluble) or lacteals (lipids as chylomicrons) → portal vein → liver (first‑pass) → systemic circulation.
Regulation
Transporter expression adapts to dietary intake, hormonal signals (insulin, glucocorticoids), and developmental stage.
Nutrition - Related Articles
- Best Herbs to Grow: A Beginner's Guide to Flavorful Gardening
- Colorado Vegetables: What You Can Grow & Where
- Carbohydrates: Properties, Types, and Energy Source
- Retinol vs. Vitamin D: Understanding Their Roles & Benefits
- Mississippi WIC Program: Apply for Free Infant Formula & Nutrition Assistance
- Island Survival: Essential Gear and Resources
- Textured Vegetable Protein (TVP): Properties, Uses & Nutritional Value