Intestine

Abstract

The intestinal epithelium represents a fine object for transport studies because of its possessing highly specific mechanisms for transporting various substances from the intestinal lumen into the blood stream. The morphology of the mucosal layer provides an enormous enlargement (by a factor of 600 relative to a cylinder; Wilson, 1962) of the absorptive surface area of the mucosal border, the following structures being responsible (see Fig. 23.1):

• 1. Folds of Kerkring (human small intestine).

• 2. Villi, finger-like structures lined with epithelial cells on the surface; the core of villi (lamina propria) consists of connective tissue with blood and lymphatic capillaries.

• 3. Microvillus structure of the brush-border membrane designated often as luminal or mucosal membrane of the columnar epithelial cells (Fig. 23.2).