Structure related to function. Adaptability to environment both physiologically and through natural selection. 4 Types of tissue 1. Epithelial - covers body surface, lines cavities. 3 types .
Endocrine glands secrete directly into the blood.
Cells in most epithelium packed tightly. Held by spot desmosome, tight or gap junctions. Connective Tissue - binds, support, protection, fills spaces, stores fat, forms blood cells. Strong but flexible. Cells called osteocytes.