You’ve probably heard the term connective tissue, and you probably just accepted that it was a part of the vast network of things going on underneath your skin. However, you probably don’t realize just how much of your body is made up of connective tissue, what it actually does in your body, and how important of a structure it really is.
The Encyclopedia Britannica defines connective tissue as a “group of tissues in the body that maintains the form of the body and its organs and provides cohesion and internal support.” Connective tissue is made up of cells and intracellular matrix (fluid outside the cells consisting of protein and polysaccharide matrix.)These tissues vary in size, structure, and density, determining the function they will perform in the body.
There are three main categories of connective tissue. This article focuses on supportive connective tissue, and fluid connective tissue.
SUPPORTIVE CONNECTIVE TISSUE
Supportive connective tissue is strong and sturdy. As the name implies, its job is to provide support to other structures in the body. It also provides protection for internal structures.
DENSE REGULAR CONNECTIVE TISSUE
Dense regular connective tissue (DRCT), consists of densely packed collagen fibers that are arranged in a parallel formation. This type of connective tissue allows room for some stretch, but is extremely resistant to tensile forces. The two types of DRCT are ligaments and tendons.
A ligament is a type of DRCT that is responsible for connecting two bones or two cartilages, creating a joint. The structure of a ligament allows for movement of the joint, but also prevents a joint from articulating in a particular direction, thereby preventing injury. For example, the tendons of the elbow prevent it from bending backwards into hyper-extension.
Tendons are flexible but inelastic bands of DRCT that connect a muscle to a bone, or other structure such as the eyeball. They are remarkably strong, able to withstand high tensile forces. This strength is necessary as the tendon bears high levels of stress during muscle contraction.
Cartilage is made up of specialized cells called chondrocytes. a strong structure that can give shape to a body part, such as the ear. This very similar to how the skeleton shapes the body. Unlike bone, however, cartilage is soft and flexible. It can also be found at the ends of bones, and it is fairly easy to damage. Cartilage has no blood supply of its own. Instead, it is reliant on the perichondrium, a dense connective tissue that surrounds the cartilage and diffuses nutrients into the cartilage. There are three types of cartilage; hyaline, fibro, and elastic.
Hyaline cartilage is strengthened by widely distributed collagen fibers. This translucent cartilage is the weakest of the three types of cartilage. It is found on the articular surface of bones, the ventral end of ribs, and in the larynx, trachea, and bronchii.
With alternating layers of hyaline cartilage matrix and dense collagen fibers, fibrocartilage is the strongest type of cartilage. It does not have a perichondrium because it usually serves as an intermediate layer of cartilage between the hyaline and a tendon or ligament. It is also found in the pubic symphysis, the annulus fibrosus (outer fibrous ring) of the intervertebral discs, menisci, and the temporal-mandibular joint (jaw).
A matrix of chondrocytes in a threaded network of elastic fibers is called elastic cartilage. Its job is to provide strength and elasticity to structures. It also maintains the shape of structures like the ear. It is also found in the walls of the arteries, the dermal layer of the skin, and in some ligaments and tendons.
Bone is made up of osseous tissue. It contains some amount of collagen and elastic tissue. It also consists of minerals, including calcium which gives the bone its strength. Bones makeup the skeleton which gives the body its shape.
FLUID CONNECTIVE TISSUE
Fluid connective tissues are considered types of connective tissue because they consist of some type of matrix.
Your blood is considered to be a type of connective tissue because it consists of a matrix, plasma. Blood consists erythrocytes (red blood cells) and leukocytes (white blood cells), which are found in the plasma matrix. Blood is responsible for carrying oxygen and other nutrients to the cells of the body.
Lymphatic (lymph) tissue is considered a connective tissue for the same reason that blood is – it consists of a matrix, known as lymph fluid. Lymph plays a role in the body’s immune system by attacking foreign substances.
Bone marrow is found within bone cavities. It is soft and flexible, and it serves to produce red blood cells and store fat.
RED BONE MARROW
Red bone marrow produces red blood cells and is found in bones of the skull, pelvis, spine, ribs, sternum, shoulder blades, and in the long bones of the arms and legs. It also removes old or dead cells from circulation. It also contains stem cells that can develop into red blood cells, white blood cells or platelets.
YELLOW BONE MARROW
Yellow bone marrow is composed of fat cells and inactive stem cells. It is found in spongy bones and in the shaft of long bones.
Other Blogs in This Series
Bone Marrow by About Education
Classification of Connective Tissue by Histology Guide
Connective Tissue: Bone, Adipose, and Blood by boundless.com
Ligament by Wikipedia
Structure and Functions of Lymphatic Tissue by IvyRose Holistic
Supportive Connective Tissues by McGraw Hill
Tendon by Wikipedia
What is Cartilage by News Medical