Cells and Tissues

When you examine a surgical incision, you are not merely looking at a disruption of flesh; you are observing a microscopic breach in a highly precise, highly organized biological architecture. To understand human healing, disease, and intervention, we must drop down to the cellular level and examine how life organizes itself into functional materials. Histology is the microscopic study of tissues, and in biological terms, a tissue is a group of similar cells working together to perform a specific function. Despite the vast complexity of human anatomy—from the pumping chambers of the heart to the filtering tubules of the kidney—the human body contains exactly four primary tissue types. Every organ you will ever assess, palpate, or treat is constructed entirely from variations of these four fundamental building blocks: epithelial, connective, muscle, and nervous tissue.