5.3.1: Introduction to Connective Tissues
- Page ID
- 53902
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Introduction to Connective Tissues
Connective tissues connect one tissue to one another, acts as support, cushions and insulates, encloses organs, and in some cases stores compounds such as calcium, phosphorous, and fats. Most connective tissues are highly vascular (contain blood vessels). There are many types of connective tissue, and they look very different but they share their origins as well as 3 main structural characteristics:
- cells - Connective tissues generally have cells that are not tightly connected to each other, the way the cells in epithelial and muscular tissues usually are. There is usually a fair amount of space between the connective tissue cells with one exception to this is adipose tissue (also known as fat tissue). Cells in these tissues are specialized and therefore are given different names such as adipocytes, chondrocytes, osteocytes, and erythrocytes.
- protein fibers - Protein fibers (collagen fibers, elastic fibers, reticular fibers) are complexes of millions of individual proteins threaded into long fibrous structures that provide strength and elasticity to the tissue as a whole. The protein fibers are so large, they are longer than the cells they surround and enmesh. Blood and lymph, being liquid connective tissues, do not have these enmeshing protein fibers, but they still have an extensive liquid extracellular matrix.
- ground substance - The materials between the cells and the protein fibers makes up the component of the tissue called ground substance. The ground substance varies widely by tissue type. For example, the ground substance of blood is the blood plasma or fluid that carries the cells and the protein fibers. Another example is bone that the ground substance is mainly composed of rigid calcium salts (hydroxyapatite).
Another term used to describe part of a connective tissue is matrix. The matrix is simply the non-cell part of the tissue, in other words, the matrix is composed of the protein fibers and the ground substance.
The diagram below describes the classification of connective tissues. You can see that the connective tissue category is subdivided into connective tissue proper, fluid tissues, and cartilage classifications as well as including bone tissue. The connective tissue proper classification is further subdivided based on how dense the cells and matrix are into the loose connective tissues and dense connective tissues subcategories. The dense connective tissues are further broken into dense regular connective tissue (fibers are parallel), dense irregular connective tissue (fibers are not parallel), and elastic connective tissue (contains a high amount of elastic fibers). There are three different types of cartilage: hyaline cartilage, elastic cartilage, and fibrocartilage. Fluid tissues include blood and lymph.
Attributions (All Connective Tissues Sections)
- "Anatomy and Physiology" by J. Gordon Betts et al., OpenStax is licensed under CC BY 4.0
- "Anatomy and Physiology I Lab" by Victoria Vidal is licensed under CC BY 4.0
- "Animal Tissues and Organs" by Berkshire Community College Bioscience Image Library is in the Public Domain, CC0
- "BIOL 250 Human Anatomy Lab Manual SU 19" by Yancy Aquino, Skyline College is licensed under CC BY-NC-SA 4.0
- "Digital Histology" by Department of Anatomy and Neurobiology and the Office of Faculty Affairs, Virginia Commonwealth University School of Medicine and the ALT Lab at Virginia Commonwealth University is licensed under CC BY 4.0
- "Human eye iris 3" by Kamil Saitov is licensed under CC BY 4.0