Category: 03. Cells, Tissues And Membranes

Every cell in the body is enclosed by a cell (Plasma) membrane. The cell membrane separates the material outside the cell, extracellular, from the material inside the cell, intracellular. It maintains the integrity of a cell and controls passage of materials into and out of the cell. All materials within a cell must have access to the…

Ideas about cell structure have changed considerably over the years. Early biologists saw cells as simple membranous sacs containing fluid and a few floating particles. Today’s biologists know that cells are infinitely more complex than this. There are many different types, sizes, and shapes of cells in the body. For descriptive purposes, the concept of a “generalized…

Cells, the smallest structures capable of maintaining life and reproducing, compose all living things, from single-celled plants to multibillion-celled animals. The human body, which is made up of numerous cells, begins as a single, newly fertilized cell. Almost all human cells are microscopic in size. To give you an idea how small a cell is, one average-sized adult…

This section provides detailed information about cell structure and function, four basic types of tissue in the human body, and the different types of membranes found in the body.