Connective Tissue Flashcards
Connective Tissue
most abundant tissue type weight
Some Systems are almost entirely connective tissue
Some Systems contain very little
All Connective tissue has 3 components
1.) Ground substance
2.) Extracellular fibers
3.) Specialized Cells
Ground Substances
Found in CT
IS an amorphous, homogenous material that ranges in texture from a liquid/gel to a calcified solid
Ground substance in soft CT
-Composed of unbranched chains of glycoproteins (glycosaminoglycans or GAGS) - Most common is Hyaluronic acid combined with 2 % protein - Large molecules help orient the formation of fibers
- is medium through which cells exchange nutrients and waste with the blood stream
-Shock absorber
-protects more delicate cells
-Thick texture makes it an obstacle for pathogens - Produce hyaluronidase - Degrades hyaluronic acid and enables microbe (pathogen) to move through tissue easier
Extracellular fibers
Three types - Collagenous, Reticular, and Elastic
Collagenous Fibers
-Strong, thick strands composed of structural protein collagen
-Organized into discrete bundles of long, parallel fibrils - Fibrils are composed of microfibrils
-Posses a tremendous amount of tensile strength - resists pulling forces - Found in tendons and ligaments
-Fiber itself is white - Tightly packed bundles are also white - Sometimes known as white fibers
- Density and arrangement - Varies depending on function of tissue as a whole - can range from loose (Surrounds and protects organs) to Dense (Seen in tendons / ligaments)
Reticular Fibers
-Composed of collagen protein
-Not as thick as collagenous
-Thin, delicate, branched into complex networks - “Mist net” - Provides support for highly cellular organs (Endocrine glands, lymph nodes, spleen, bone marrow, and liver), also found in blood vessels (prevents aneurysms), nerves, muscle fibers, and capillaries
Elastic fibers
-Composed primarily of the protein elastin
-Branched and form complex networks - lack tensile strength of collagenous fibers
-Composed of bundles of microfibrils - they are coiled
-Can stretch and contract - like a rubber band
-Occur in tissues that are subject to stretch (vocal cords, lungs, skin, blood vessel walls)
-Due to the yellow color, can be referred to as yellow fibers
Specialized Cells
Two categories
Fixed - remain in CT, involved in the production and maintenance of the matrix
Transient - Pass in and out of CT, involved in the repair and protection of tissues
Fixed cells
Most noteworthy one: Fibroblast
fat cells
Reticular cells
Fibroblasts
-Large, irregular shaped
-Manufacture and secrete both fibers and ground substance
-Reproduce - Metabolically very active
-Each type of CT is characterized by a predominant fibroblast - Cartilage (Chondroblasts), Bone (Osteoblasts) - As cell mature, they become less active - when this happens they adopt the suffix -cyte (Chondrocyte, osteocyte, fibrocyte)
Fat cells
-Adipose cells or adipocytes
- Young cells - resemble fibroblasts
-As they mature - they fill with lipids and increase in size - Nuclei are pushed to one side
-When in groups - Adipocytes become adipose tissue
Reticular cells
-Flat, star-shaped cells - long outreaching arms that tough other cells - form netlike connections throughout the tissue they compose
-Function is debated - Most agree that they help with immunity and manufacture reticular fibers - Part of the immune system (Lymph nodes, spleen, Bone marrow)
Transient (Wandering Cells)
-Many different types
-Three common types - Leukocytes, Mast cells, microphages
-All are WBCs
Leukocytes
-Found in the blood ad move into CT when inflammation or infection is present
-Bigger than RBCs - Can squeeze through tiny walls through a process called diapedesis
-important members of immune system
-Five diff types - Most protect the body by engulfing and digesting pathogens - Others make antibodies that attach to pathogens and destroy them
Mast Cells
- Oval cells that are easily identified by the large numbers of dark-staining granules in cytoplasm - the granules contain heparin and histamine
-Biochemicals that start an inflammatory response
-Histamine - increases blood flow - make capillaries leaky
-Heparin - Prevents clotting - makes sure blood flow is increased