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Connective Tissue
holds structures together; underlying framework
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Types of connective tissue
- connective tissue proper (loose and dense)
- supporting connective tissue (cartilage and bone)
- fluid type connective tissue (blood)
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Connective tissue proper
- holds/fastens structures together and provides either flexible or inflexible rigid support
- cell types include fibroblasts, adipocytes, macrophages, mesenchymal cells, melanocytes, mast cells, chondrocytes, and osteocytes
- *(AFCMMMOM - Another Frikken Chem Minor Means More Organic Matter)
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fibroblasts
- makes collagen, elastic and reticular fibers
- *fibro makes fiber
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mesenchymal cells
embryonic stem cells still capable of differentiating into specialized cell types
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melanocytes
pigment cells
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mast cells
contain histamine and stimulate inflammation upon tissue injury
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chondrocytes
cartilage cell
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extracellular matrix (ECM)
formed from cells in the connective tissue and is composed of fibers and ground substance
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fibers (in ECM)
collagen, elastic, reticular
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ground substance (in ECM)
- tissue fluid, proteins and polysaccharides
- the fluid determines consistency of the ground substance
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loose (areolar) connective tissue
- loosely woven tissue that fills spaces b/t organs
- cells are suspended in an abundance of a "syrupy" ground substance
- arrangement of fibers allows for distortion w/o damage
- Ex: loose ct found b/t skin and underlying skeletal muscle
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adipose (fat) tissue
- composed chiefly of adipocytes
- white fat pale yellow appearance, less vascularized than brown fat
- brown fat highly vascularized tissue used for heat production via neural stimulation
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dense regular connective tissue
- densely packed collagen fibers with collagen fibers all in parallel arrangement providing strength along orientation of fibers
- very strong in one direction
- Ex: tendons (connect musclce to bone - i.e. Achilles tendon), ligaments (connect bone to bone - i.e. anterior cruciate ligaments)
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dense irregular connective tissue
- densely packed collagen fibers that are randomly located providing strength in all directions
- Ex: dermal layer of skin, perichondrium, periosteum, fibrous capsule of organs
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elastic tissue
- densely packed regular array of elastic fibers
- thinner, parallel array
- usually drawn in black from stain
- Ex: wall of large and medium sized arteries; ligaments b/t adjacent vertebrae (found in ligaments and spine)
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Cartilage
- semisolid matrix that is more rigid and supportive
- types of cartilage: hyaline cartilage, fibrocartilage, and elastic cartilage
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hyaline cartilage
- most common
- chondrocytes reside in unique space of dense matrix called a lacunaECM characterized as being avascular, glassy appearing, stiff, rigid, and slightly flexible
- composed of densely packed collagen fibers and a ground substance of chondroitin sulfate and hyaluronic acid (but no calcium salts like in bone)
- Blood vessels for nutrient delivery are located in surrounding perichondrium
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hyaline cartilage locations
- embryonic skeleton (as a baby)
- costal
- tracheal
- laryngeal
- nasal
- articular cartilages
- bronchi and bronchioles
- covers ends of bones
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fibrocartilage
- chondrocytes reside in lacunae
- ECM thick, wavy bundles of collagen fibers allowing for some compression to tissue
- maintains less ground substance and an abundance of densely interwoven collagen fibers
- Ex: intervertebral discs, symphyses, menisci
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elastic cartilage
- most flexible
- chondrocytes reside in lacunae
- ECM has less densely packed collagen fibers and higher abundance of elastic fibers providing flexibility to tissues
- Ex: external ear (most common), epiglottis, Eustachian tube
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