connective tissue forms metabolic and structural connections between tissues found ___________ in...
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Connective TissueForms metabolic and structural connections between tissues
Found ___________ in the body and represents most abundant tissue by weight.Examples: Blood, tendons, fat, cartilage, bone
Some systems are almost exclusively composed of connective tissueSkeletal, integumentary
Derived from _____________
Is vascularized.Loose & Adipose = good supply, Dense = poorly supplied
Form and function may varycan be elastic and flexible, rigid, semisolid, liquidReserve for energy, protective sheath, provides framework of structural
support, transport medium, promotes healing, controls foreign invaders
Connective Tissue Components
3 major components of connective tissue:Extracellular fibers, Ground substance, CellsExtracellular Matrix = Extracellular fibers + Ground
substanceMatrix surrounds and separates the cells, providing important
structural and nutritional support to them, allowing them to be farther apart than epithelial cells.
1. Extracellular fibersCollagenous, Reticular, Elastic
2. Ground substanceLiquid, solid, or gel
3. CellsFixed cells
Fibroblasts, Adipocytes (fat cells), Reticular cellsWandering cells
Mast cells, Leukocytes (white blood cells), Macrophages (fixed and wandering)
Connective Tissue Components: Ground Substance
An amorphous, homogenous material that ranges from ______ to _____ to _______.
Composed of glycoproteins called __________________ (GAGs)hyaluronic acid
Help to orient fiber formation in connective tissue.
Is medium through which cells exchange nutrients and waste with the bloodstream.
Acts as ______ absorbing cushion and helps to protect the delicate cells that it surrounds.
Serves as obstacle for invading microorganisms.
Fibers of Connective TissueCollagenous:
Most common fiber found in the bodyStrong, thick bands composed of collagen (structural
protein).Organized into bundlesResist pulling forces, so they are found in tendons
and ligaments that are continuously being pulled and stretched.wavy appearance when not stretched
Sometimes called white fibersDensity and arrangement can vary depending on tissue function.
Loose around organs to dense within tendons.
Fibers of Connective TissueReticular:
Composed of collagen, but are not thickThin, delicate, branched into complicated networks.Form support for around highly cellular organs
endocrine glands, lymph nodes, spleen, bone marrow, liverFound around blood vessels, nerves, muscle fibers,
capillaries
Elastic:Composed primarily of protein elastin.Are branched and form networksCan stretch and contract.Found in tissues that stretch: vocal cords, lungs, skin, blood
vessel walls.May be referred to as yellow fibers.
Major Cell Types of Connective Tissue
Fixed Cells:Remain in the connective tissueProduce and maintain the matrix
Fibroblast:secrete fibers and ground substance of the matrixCan reproduce and are metabolically active.Name is based on location
o Chondroblast (cartilage), osteoblast (bone), etc.
As the cells mature and the matrix is formed, cells become less active and are called –cytes. o Chondrocyte, osteocyte, fibrocyteo Can revert back to blast if more matrix is needed.
Major Cell Types of Connective TissueFixed cells continued.
Adipose cells/Adipocytes:Found throughout connective tissueResemble fibroblasts early on, but as
they age they become filled with lipid and swell.nucleus gets pushed to the side
Adipocytes clustered together form adipose tissue.found all over, but is prominent under
the skin, behind the eyes, around the kidneys, and in the abdomen
Reticular Cells:Flat, star-shaped cells that form net-like
connections with other cellsManufacture of reticular fibers.Found in tissues of the immune system:
lymph nodes, spleen, bone marrow
Major Cell Types of Connective Tissue
Wandering Cells:Move in and out of connective tissue as needed.
Leukoctyes: (white blood cells)Found in blood and move into connective tissue during periods of
infection.Squeeze through the simple squamous epithelium of blood vessels
(diapedesis) Important in immune function- engulf and digest invaders or
produce antibodies against them
Mast cells Carry histamine and heparin granules which initiate inflammatory
response when released into tissueUsually found near blood vessels
Major Cell Types of Connective Tissue
Wandering cells continued..Macrophages:
Phagocytotic scavengers that may be either fixed or transient in connective tissue.
Engulf microbes, dead cells and debris that are digested by the macrophage’s lysosomesdrawn to sites of infection where they engulf invaders
Given different names depending on locationsKupffer cells in liver, microglial cells in brain