In vertebrate animals there are four large groups of tissues: O muscular, O nervous, O connective (also covering bone, cartilaginous and blood tissues) and epithelial, constituting specific subtypes that will form the organs and body systems.
For example: Blood is considered a connective tissue, with diverse cells (red blood cells, leukocytes and platelets) and plasma (water, mineral salts and various proteins).
In invertebrates these types of tissue are basically the same, but with simpler organizations. Most tissues, besides being composed of cells, include intracellular (interstitial) substances.
Epithelium → lining of the external surface of the body (skin), organs (liver, lung and kidneys) and internal body cavities;
Conjunctive → consisting of cells and abundant extracellular matrix, with function of filling, sustaining and transporting substances;
Muscle → consisting of cells with contractile properties;
Nervous → formed by cells that make up the central and peripheral nervous system (the brain, spinal cord and nerves).