In this video, we're going to begin our lesson on the classes of connective tissue. And so recall from our previous lesson videos that connective tissue is the most diverse primary type of tissue in terms of both its structures and its functions. And so because connective tissues are so diverse, they can actually be grouped in slightly different ways. And so you'll find that different textbooks and different professors can group connective tissues in slightly different ways. And so here in this video, we're going to explain how we've strategically decided to group connective tissues in our lesson. And so in this lesson, we are going to be grouping connective tissues into two major classes that you can see number down below number one and number two. And so the first major class of connective tissue in our lesson is going to be connective tissue proper, which is also sometimes referred to as general connective tissue or fibrous connective tissue. And the second major class of connective tissue in our lesson is going to be specialized connective tissue. And so connective tissue proper once again, is also sometimes referred to as general connective tissue because these tissues tend to have more generalized functions that are not really specific or limited to any particular body system or body body area or body process. But instead these generalized functions tend to be more basic and fundamental and more general and more widely utilized throughout multiple body systems and multiple body areas and multiple body processes. And so the ground substance of these tissues tends to be gelatinous or more of a semifluid something in between a solid and a liquid. And so connective tissue proper or general connective tissue once again, is also sometimes referred to as fibrous connective tissue because these tissues tend to be really rich in terms of their protein fibers that are found in their extracellular matrix. And those protein fibers often are pretty conspicuous or distinct and easily seen under a light microscope. And so connective tissue proper or general connective tissue or fibrous connective tissue, whatever your professor decides to use is always going to include both loose and dense connective tissues. And so, moving forward in our course, in different videos, we'll be able to talk more about loose connective tissues and dense connective tissues. And so once again, the second major class of connective tissues in our lesson is going to be specialized connective tissue. And as its name implies, with the term specialized, these tissues tend to have more highly specific functions that tend to be more unique to the particular tissue. And those specific functions tend to be more specific or limited to just one or a few body systems. And the ground substance of these tissues is either a solid or a liquid rather than being gelatinous and so specialized connective tissue is going to include cartilage, bones and blood and lymph. Now, as we'll learn, moving forward in our course, cartilage and bones do have protein fibers in their extracellular matrix, but they tend to be a little bit harder to see under a light microscope without specialized staining techniques and blood and limp, don't really have those protein fibers or those fibrous proteins in their extracellular matrix. And so if we take a look at our image down below, notice that we're showing you how we are grouping connective tissues in our lesson. And so notice that immediately we have connective tissues at the top and we can group them into two major classes. Once again, we can group them into connective tissue proper or general connective tissue or fibrous connective tissue, or we can group them into specialized connective tissue. And so recall that connective tissue proper or general or fibrous connective tissue is going to always include both loose and dense connective tissues and the specialized connective tissues include cartilage, bone and blood and lymph. And so as we move forward in our course, we'll be able to talk more details about each of these connective tissues. Now notice down below what we have is a scale or a spectrum of the ground substance viscosity in the extracellular matrix or how thick the ground substance is. And so what you'll notice is that in this scale or in the spectrum, on one extreme or one end, what we have is a rock hard solid ground substance and on the other extreme, the other end, what we have is a liquid ground substance. And so recall once again that connective tissue proper or general or fibrous connective tissues, which includes loose and dense, they tend to have more of a gelatinous ground substance that is going to be more of a semifluid in between a solid and a liquid. And so you can see here where they lie on the spectrum. Whereas again, with specialized connective tissues, they are either going to have a solid or a liquid ground substance. And so notice that both bone and cartilage are going to have more of a solid ground substance and then blood and limp is going to have more of a liquid ground substance. And so this here concludes our brief introduction to the classes of connective tissue. And again, as we move forward in our course, we'll be able to talk about each of these connective tissues in their own separate videos in more detail. And so I'll see you all in our next video.

Classes of Connective Tissue

Grouping Connective Tissues

Marco and Yara are discussing connective tissue and Marco states that blood can't be a connective tissue because it's a liquid. Yara claims that blood is a specialized connective tissue with a fluid ECM. Who is right and why?