There is a great deal of loose connective tissue in the body, and — like other connective tissue — it provides a matrix of support and cushioning that is designed to protect delicate organs and other vulnerable parts of the body. It's found around organs and blood vessels, under the dermis layer of skin, and in the structure of a number of body systems, including the reproductive, digestive, urinary, and respiratory. People may also refer to it as areolar tissue.
Connective tissue in general is characterized by the presence of fibroblasts, cells that product collagen and elastin, two types of fibers that make tissues stronger and more resilient. In the case of loose connective tissue, the cells are very loosely packed and the tissue is quite soft, in contrast with fibrous or dense connective tissue, where the fibroblasts are very densely arranged and the tissue is extremely firm. Tendons are an example of dense connective tissue.
The space between fibroblasts is filled with fluids and ground substance, a gelatinous material. This provides ample space for blood vessels and nerves to move through the tissue. For this reason, this tissue is often found at boundaries in the body, supplying other types of tissue with blood and lymph and carrying wastes away. It underlies mucus membranes in areas like the digestive tract and can also be found where the skin and the muscles connect.
Loose connective tissue is rich in blood and lymph because of the numerous vessels that run through it. Because it is not very fibrous, it is highly flexible and malleable. This type of tissue acts as a cushion to absorb and distribute impacts so that underlying structures are not damaged, protecting the organs and other body parts it is connected to. It also rapidly restores blood supply after injuries by providing means for blood and lymph to reach the site of an injury.
Other types of connective tissue in the body include cartilage, bone, blood, skin, and tendons. These forms of tissue are more differentiated and specialized to perform specific tasks in the body. A number of diseases can affect the connective tissue, and some people have genetic conditions that interfere with the production or healing of connective tissue and the fibers it contains. Other people develop infections and inflammation in their connective tissue that can lead to permanent damage in some cases.