Tissues, Part 2 - Epithelial Tissue: Crash Course Anatomy & Physiology #3

The Role of Epithelial Tissue00:00:00

Epithelial tissue creates essential order within the body by organizing organs and systems, preventing chaos similar to managing a crowded room. It lines and covers the body, serving as a protective barrier.

Structure and Classification00:03:22

Epithelial tissue is classified by cell shape—squamous (flat), cuboidal (cube-like), and columnar (tall)—and by layering, which can be simple (one layer) or stratified (multiple layers). These characteristics directly relate to the tissue's function, such as protection or absorption.

Polarity and Permeability00:07:06

All epithelial cells exhibit polarity, featuring an apical side exposed to cavities or the outside, and a basal side anchored to connective tissue. This structure allows for selective permeability, enabling critical processes like digestion and filtration.

Glandular Epithelium00:08:09

Glandular epithelium is specialized to secrete substances. It forms endocrine glands, which release hormones directly into the bloodstream, and exocrine glands, which transport substances like sweat and mucus through ducts to epithelial surfaces.