Connective TissueAs the name implies, connective tissue serves a "connecting" function. It supports and binds other tissues. Unlike epithelial tissue, connective tissue typically has cells scattered throughout an extracellular matrix.
Loose Connective TissueIn vertebrates, the most common type of connective tissue is loose connective tissue. It holds organs in place and attaches epithelial tissue to other underlying tissues.
Loose connective tissue is named based on the "weave" and type of its constituent fibers. There are three main types:
- Collagenous Fibers
Collagenous fibers are made of collagen and consist of bundles of fibrils that are coils of collagen molecules.
- Elastic Fibers
Elastic fibers are made of elastin and are stretchable.
- Reticular Fibers
Reticular fibers join connective tissues to other tissues.
Fibrous Connective TissueAnother type of connective tissue is fibrous connective tissue which is found in tendons and ligaments. Fibrous connective tissue is composed of large amounts of closely packed collagenous fibers.
Specialized Connective TissuesAdipose
Adipose tissue is a form of loose connective tissue that stores fat.
Cartilage is a form of fibrous connective tissue that is composed of closely packed collagenous fibers in a rubbery gelatinous substance called chondrin. The skeletons of sharks and human embryos are composed of cartilage. Cartilage also provides flexible support for certain structures in adult humans including the nose, trachea and ears.
Bone is a type of mineralized connective tissue that contains collagen and calcium phosphate, a mineral crystal. Calcium phosphate gives bone its firmness.
Interestingly enough, blood is considered to be a type of connective tissue. Even though it has a different function in comparison to other connective tissues it does have an extracellular matrix. The matrix is the plasma and erythrocytes, leukocytes and platelets are suspended in the plasma.