And these nerve cells are responsible for generating action potential, our electrical signals that basically allow the cells to communicate with one another and will focus more on what an action potential is when we'll discuss the nervous system of the human body. Now, these are the four different types of tissues and a tissue is basically individual cells that are organized to carry a specific type to carry out a specific type of function. Now the question is, what exactly is found in between these cells in our tissue? So this is known as the extracellular matrix, and there are three major constituents of the extracellular matrix. So we have structural proteins, Adhesive proteins and proteoglycan. So once again, groups of cells that carry out a similar function are called tissues.