Connective tissue, right now may be thinking that this subject is very simple, and in all reality it is although some parts are complex and were difficult to learn at first. There are four different types of connective tissue; proper, cartilage, bone, and blood. You might be thinking what do all four of this have in common? The answer is mesenchyme. Mesenchyme is the base to all of these types when you are a little embryo. These tissue has four functions to carry out and those are transportation, protection, insulation, and binding and support. Connective tissue is made up of ground substance, extracellular matrix, and fibers. Four different types of cells branching off from mesenchyme make up the different types of tissues. The cells called Fibroblasts group up to make Fibrocyte, then these group up and make the two types of connective tissue proper. Chondroblasts group to make Chondrocyte, which team up to make the three types of Cartilage. Osteoblast cells form into Osteocyte, which then are turned into the two types of Osseous (that is the fancy science term for bone). Lastly Hematopoietic stem cells form blood cells which form blood.
Lets start with ground substance. The definition of ground substance is unstructured material that fills the space between cells. This means that ground substance could be Proteoglycans, tissue fluid or an adhesion protein. All three of these function as a molecular sieve through which nutrients diffuse between the blood capillaries and cells. Now onto fibers. Collagen, the first type of fiber, is very tough and it proves to provide high tensile strength. The next is Elastic, this is what keeps your ear from falling off, these fibers are long and allow for stretch. Last we have reticular fibers. This are delicate networks of branched collagen fibers.
Now onto the tissues that each of the cells produce. Mesenchyme first makes connective tissue embryonic. This goes on to make all the other connective tissues and is only found in the embryo stage of our lives. Connective tissue proper has two subtypes, loose and dense. Connective tissue proper loose has three subcategories. These are Areolar, Adipose, and Reticular connective tissue. This is a picture of Adipose connective tissue. A common name for this substance is fat, but for this i will stick to it’s scientific term. Adipose reserves food for the body, insulates, and are the means of nutrients for highly active organs. Adipose is found in the breasts, around the kidney’s and in the abdominal region.
Areolar connective tissue wraps and cushions organs because it has a gel-like matrix with three of the connective tissue fibers. It is found in many places throughout the body.
Reticular Connective Tissue is found in the body in the lymph nodes, bone marrow and in the spleen. It is found in these places because the cells form a internal soft skeleton that can support different cells. Its matrix is made up of a loose ground substance and reticular fibers. Hence the name. These are types of loose connective tissue.
The next class of connective tissue proper i would like to talk about is Dense. Unlike loose, dense has two different types to it. Regular and irregular. Dense regular is made by parallel fibers attaching bone to bone or bone to muscles. So obviously it would be found in all tendons and ligaments.
Dense Irregular tissue is built by mainly collagen fibers, but it includes some elastic fiber. It is made to withstand tension in multiple directions. The most common place that it is found is the digestive tract.
It is now time for cartilage! Cartilage takes place in three different forms. Hyaline, Elastic, and Fibrocartilage. Since the other two’s matrix is similar to Hyaline we’ll start with it first. Hyaline Cartilage has a firm mstrix that morphs to a certain shape and has an unimaginable amout of collagen fibers. This cartilage supports, protects, cushions, but at the same time resists compression. It is found at the end of the nose, the trachea, larynx, and most importantly it forms the costal cartilages. Those are the cartilages that connect the ribs to the sternum.
Elastic Cartilage is very similar to Hyaline cartilage. The only real difference is that it has more elastic fibers. Elastic Cartilage maintains shape and structure while still aloowing for flexibility. This stuff is what lets the outer ear keep its’ shape and flexibility.
Fibrocartilage is less firm than Hyaline Cartilage but instead it has thicker collagen fibers. This makes it great at absorbing compression and providing strength. It is found in the discs of the knee joint, the pubic symphysis, and most importantly between the vertebraes.
Bone wants it time in the spotlight now. Bone has two different types spongey and hard. If that last sentence didn’t get you wondering about wheter or not bone can be soft, i’ll help ease your mind with an overall yes it can. The two types of bone are very similar in all ways. The function of bone is to support and protect a humans inner organs. Without bone we could not walk because our muscles wouldnt have a lever to act apon. Inside bone there is a substance called bone marrow. This substance is so crucial because without it we wouldn’t be able to produce blood. Without blood there wouldn’t be any way to send oxygen around the bidy. And without oxygen the human race would DIE!
Our last stop on the four major connective tissues is blood. Blood’s function is very simple. Travel around the body delivering nutrients, respiratory gases, and wastes. Blood is contained within blood vessels and red and white blood cells are in a plasma matrix.
Well now that the major connective tissues have been thoroughly discussed, i think it is time to shine some light on the minor ones. The minor connective tissues include Epithelial membranes, Nervous tissue, and Muscle tissue. There are three types of Epithelial membranes, cutaneous membrane, Mucous membrane, and the serous membrane. The Cutaneous membrane sounds complex but its not. It is the skin that covers our bodies. The mucous membrane lines the cavaties open to the exterior with mucous. This meaning the digestive and respiratory tracts. And the last membrane, serous. The Serous membrane is found inside the body in the closed ventral cavity.
Nervous tissue is complicated in structure but simple in function. This tissue consits of branching neurons with long cellular processes and support cells. The function of them are to relay messages to the body via electronic signals. Nervous tissue lies in the brain, spinal cord, and the peripheral nerves. This is what nervous tissue looks like.
Last but one of the most important types of connective tissues is muscle. There are three different types of Muscle Tissue. These types are, Skeletal, Cardiac, and Smooth.
Skeletal Muscle plays a key role in our movement. Without it we would be a sack of bones skin and organs. Skeletal muscles are long and cyndrical with cells that have many cells and obvious seperations between each individual strand. Skeletal muscles gives us the control to move voluntarily. They attatch to either bone or skin or both.
This is Cardiac Muscle. It does one job and one job only. That one job is to propel blood into our circulatory system. Cardiac muscle is different in look than skeletal muscle. It is branching across the heart with only single nucleus cells and they muscles interlock at certain points with intercalated discs.
Smooth muscles differ greatly from skeletal and Cardiac. They are not striated, and they are made up of spindle shaped cells with a nucleus in the center. Their job is to propel food along our internal passageways. They are found in the walls of hollow organs such as the stomach, small intestine, andlarge intestine.
This marks the end of my super long blog entry on connective tissues, how they work, what they are made of, and where in the body you can find them. Thanks for reading, even the boring parts.