Blood tissues are found inside the blood vessels (arteries, arterioles, capillaries, venules and veins; see systemic circulation for further details about the path the blood follows and the names of specific blood vessels) and also within the chambers of the heart.
Sheets of loose connective tissue that bind muscles and other structures together are called fascia. Collagen, elastin, and other proteins are found in the matrix of loose connective tissue. Both dense and loose connective tissue are derived from cells called fibroblasts , which secrete the extracellular matrix.
Epithelial cells form the thin layer of cells known as the endothelium, which is continuous with the inner tissue lining of organs such as the brain, lungs, skin, and heart. The free surface of epithelial tissue is usually exposed to fluid or the air, while the bottom surface is attached to a basement membrane.
Muscle Tissue. Muscle tissue is made of "excitable" cells that are capable of contraction. Of all of the different tissue types (muscle, epithelial, connective, and nervous), muscle tissue is the most abundant in most animals. Muscle Tissue Types. Muscle tissue contains numerous microfilaments composed of the contractile proteins actin and myosin.