Epithelial tissue covers and protects surfaces and forms a selective barrier. In the image below, the epithelial tissue shown is a transitional epithelium. It is a stratified epithelium with cells that can stretch and change shape, found lining the urinary bladder; it allows expansion and recoil.

The connective tissue supports, binds, and connects other tissues and organs; provides a structural framework; stores energy (fat); protects organs; transports substances (blood); involved in tissue repair and defense. The connective tissue shown in the image is areolar connective tissue. This is a loose connective tissue with a gel-like matrix containing collagen and elastic fibers; it cushions organs, provides support, and allows diffusion of nutrients.

Muscle tissue is responsible for producing force and movement; enables locomotion, posture maintenance, and involuntary movements such as peristalsis and blood circulation. The muscle shown below is a smooth muscle. This type of muscle is non-striated, involuntary muscle tissue composed of spindle-shaped cells; it controls movements in hollow organs like intestines and blood vessels.

Nervous tissue transmits electrical impulses to coordinate body functions; processes sensory information; controls and regulates bodily activities; involved in memory, reasoning, and response to stimuli. Below shows a nerve fiber (teased), elongated axons of neurons isolated for study; responsible for transmitting electrical impulses throughout the nervous system.