Cartilage is a vital structural and functional component in the human body, but what exactly is cartilage, and what does it do?
At its most basic level, cartilage is a connective tissue found throughout the body. You can find it in the ears, rib cage, nose, spine, bronchial tubes, and the end of bones (to stop the hard bone from rubbing together). You've probably heard that protecting the cartilage is crucial to maintaining joint health, especially as you age. Additionally, for athletes, understanding the basics of cartilage can help extend their careers. But why? Let's get into it.
As we touched on above, cartilage is a type of connective tissue. Connective tissue is any type of biological tissue with an extensive extracellular (outside the cells) matrix that helps support, bind together, or protect the body's organs.
Our bodies have many types of connective tissue, but they all function differently. For example, muscles and bones are also connective tissues. However, if you break a bone or tear a muscle, you'll likely know about it straight away because these tissues contain nerves that will fire off your pain receptors. In contrast, cartilage doesn't have nerves, so you often don't know you've damaged your cartilage until the underlying bone is damaged.
Additionally, cartilage doesn't heal in quite the same way other connective tissues, like muscles, do.
Cartilage comprises specialized cells called chondrocytes that produce a matrix of proteoglycans (a type of protein) and collagen. Proteoglycans provide hydration and swelling pressure, allowing the cartilage to withstand compressional forces. Conversely, collagen is much more rigid and resistant to stretching and therefore plays a critical role in the structural support of the extracellular matrix. Without collagen, the cartilage wouldn't hold its shape, and without proteoglycans, the cartilage would be too brittle and easily damaged.
There are three main types of cartilage:
Elastic Cartilage - Present in the nose, ear, and parts of the lungs. This type of cartilage, sometimes called yellow fibrocartilage, is highly flexible, allowing it to quickly revert to its original shape after being deformed. For example, if you gently twist your upper ear, it will bend but go back to its original position once you let go.
Hyaline Cartilage - This type of cartilage lines the joints of the body, appearing at the end of bones, as well as the septum in the nose and parts of the respiratory tract (breathing tube). Hyaline cartilage is bluish-white in color, and its primary function is to minimize friction between bones. It's also the most common type of cartilage in the human body.
Fibrocartilage - This type of cartilage is very dense, tough and strong, and is primarily found in the menisci of the knee and the intervertebral discs of the spine. It's tough enough to resist high compressional forces and distribute them evenly to the underlying bone, ensuring that no one part of the bone receives all the force.
The function of cartilage differs depending on where it is located in the body. For example, some cartilage allows organs to maintain their shape, like the ears and the nostrils. The cartilage in the trachea enables your airways to stay open and flexible, no matter if you're lying down, standing up or moving around. The cartilage in weight-bearing bones helps your body cushion the impact of movement and disperse your weight through the joints.
Joint injuries, aging, excessive weight, and infection can all damage your cartilage. Unfortunately, cartilage only has a minimal ability to heal itself once damaged because it doesn't have a blood supply. Treatments include dietary supplements, physiotherapy, and lifestyle changes like losing weight or avoiding strenuous exercise. In more severe cases, people might require surgical intervention in the form of joint replacements, fusions, or other repairs.