- [Instructor] Alrighty, so
we're talking about cartilage, and cartilage is, at the most basic level, a connective tissue that can be found throughout the entire human body. And so cartilage is an
extracellular tissue secreted by cells called chondrocytes, which are derived from the
same precursor cells as bone, the fibroblast. Now chondrocytes secrete fibrous materials such as collagen, which is
a strong fibrous protein, and elastin, which as it's
name sort of sounds like, is an elastic protein that provides a rubbery, elastic component to cartilage. And one thing that I just
wanted to touch on briefly is something that I personally
sort of struggled with for a little while before I realized, ah that's what it is. So cartilage basically is, as I said, a connective tissue, just like bone, just like fat and other connective tissues that you find in the body. Collagen, on the other hand, is one of the building
blocks of cartilage. So, I feel like sometimes
it was easy for me to confuse these two terms, but realize that cartilage
is actually referring to the type of tissue
and collagen is referring to the type of protein
that is found in cartilage. Now the key thing to remember
about collagen and elastin, that make up cartilage, is that it gives cartilage
strength and flexibility. And a couple of other
key points to remember about cartilage is that
it is not innervated, meaning it doesn't have nerve cells, and it is also avascular, meaning it doesn't have any vasculature that runs through it. In other words, it doesn't have arteries and veins and blood
vessels that run through. Instead, cartilage receives nutrition and immune protection from
the surrounding fluid. So, there are three
main types of cartilage found within the body. The first type is called
hyaline cartilage. So, you can find hyaline cartilage in the larynx and trachea in
the throat portion of the body, and then also in all of the joints where the surfaces of bones
are articulating each other. So this is called articular cartilage. And, the main purpose of hyaline cartilage is to reduce friction and absorb shock. The second type of cartilage that you will find in the human body is called elastic cartilage, which can be found in the
shape of the outer ear, and also the epiglottis
which is the structure that protects your airway
whenever you are swallowing food. And so the main purpose
of elastic cartilage is to provide shape and support. And then finally we
have fibrous cartilage. And you can find fibrous cartilage in the intervertebral discs in the spine and also in an area of the pelvis called the pubic symphysis which is where the two
halves of your pelvic bones come together to form a joint there. And the main purpose of fibrous cartilage is to provide rigidity
and to absorb the shock that is transmitted between these joints.