Chapter Review Review 4.1 Types of Tissues

1. A tissue is a group of cells, usually with similar embryological origin, specialized for a particular function.

2. The tissues of the body are classified into four basic types: epithelial, connective, muscular, and nervous.

4.2 Cell Junctions

1. Cell junctions are points of contact between adjacent plasma membranes.

2. Tight junctions form fluid-tight seals between cells; adhering junctions, desmosomes, and hemidesmosomes anchor cells to one another or to the basement membrane; and gap junctions permit electrical and chemical signals to pass between cells.

4.3 Comparison Between Epithelial and Connective Tissues

1. Epithelial tissue has many cells tightly packed together and is avascular.

2. Connective tissue has relatively few cells with lots of extracellular material.

4.4 Epithelial Tissue

1. The subtypes of epithelial tissue include surface epithelium and glandular epithelium.

2. Epithelial tissue consists mostly of cells with little extracellular material between adjacent plasma membranes. The apical, lateral, and basal surfaces of epithelial cells are modified in various ways to carry out specific functions. Although epithelial tissue is avascular, it has a nerve supply. The high rate of cell division gives epithelial tissue a high capacity for renewal.

3. Surface epithelium can be