Body tissues

A tissue is a group of similar cells, together with the material around them, that work together to perform a particular function. Tissues form the level of organisation between individual cells and whole organs. The human body is built from four basic types of tissue — epithelial, connective, muscle and nervous — and almost every organ is a combination of these, arranged so that their different properties complement one another.

Epithelial tissue covers body surfaces and lines cavities, tubes and glands. Its cells are packed closely together to form continuous sheets that protect underlying structures, control what passes across them, and secrete substances such as mucus and enzymes. Connective tissue, by contrast, supports and binds other tissues; it is marked by cells, including fibroblasts, scattered within an abundant surrounding material called the extracellular matrix. Bone, cartilage, fat, tendons and blood are all classed as connective tissues, ranging from rigid to fluid.

Muscle tissue is specialised to contract and produce movement. Skeletal muscle, attached to bones and under voluntary control, moves the body, while smooth muscle in the walls of organs such as the gut and blood vessels works automatically to move their contents or change their size; cardiac muscle drives the heart. Nervous tissue, made of neurons and supporting cells, generates and transmits electrical signals, allowing the body to sense its environment and coordinate its responses. Understanding these four tissue types is fundamental to anatomy because it explains how organs are constructed and how they carry out their roles.

Frequently asked questions

What are the four basic types of tissue?

Epithelial, connective, muscle and nervous tissue; most organs are built from a combination of these working together.

How does skeletal muscle differ from smooth muscle?

Skeletal muscle attaches to bones and is under voluntary control to move the body, while smooth muscle in organ walls works automatically without conscious control.

What does connective tissue do?

It supports and binds other tissues and includes bone, cartilage, fat, tendons and blood, all marked by cells set within an abundant surrounding matrix.