Connective Tissue

Dense Fibrous Connective Tissue
Dense Fibrous Connective Tissue. Ed Reschke/Photolibrary/Getty Images

Connective Tissue

As the name implies, connective tissue serves a "connecting" function. It supports and binds other tissues in the body. Unlike epithelial tissue which has cells that are closely packed together, connective tissue typically has cells scattered throughout an extracellular matrix of fibrous proteins and glycoproteins attached to a basement membrane.

Loose Connective Tissue

In 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 are made of collagen and consist of bundles of fibrils that are coils of collagen molecules.
  • Elastic Fibers are made of the protein elastin and are stretchable.
  • Reticular Fibers join connective tissues to other tissues.

Dense Connective Tissue

Another type of connective tissue is dense or fibrous connective tissue, which is found in tendons and ligaments. These structures help attach muscles to bones and link bones together at joints. Dense connective tissue is composed of large amounts of closely packed collagenous fibers. Much of the dermis layer of the skin is composed of dense irregular connective tissue.

Specialized Connective Tissues

Adipose

Adipose tissue is a form of loose connective tissue that stores fat.

Adipose lines organs and body cavities to protect organs and insulate the body against heat loss. Adipose tissue also produces endocrine hormones.

Cartilage

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

Bone is a type of mineralized connective tissue that contains collagen and calcium phosphate, a mineral crystal. Calcium phosphate gives bone its firmness.

Blood

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 consists of the plasma, while red blood cells, white blood cells, and platelets are suspended in the plasma.

Lymph

Lymph is another type of fluid connective tissue. This clear fluid originates from blood plasma that exits blood vessels at capillary beds. A component of the lymphatic system, lymph contains immune system cells that protect the body against pathogens.

Animal Tissue Types

To learn more about animal tissues, visit: