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