BIO 201 Chapter 4: Connective Tissue

Connective tissue

• binds together, supports, and strengthens other body tissues

• protects and insulates internal organs

• compartmentalizes structures such as skeletal muscles

• serves as the major transport system within the body (blood, a liquid connective tissue)

• contains and distributes almost all the blood vessels in the body

• is the primary location of stored energy reserves (adipose, or fat, tissue)

• is the main source of immune responses

Fibroblast

• Large, flat cells with branching processes

• Present in all the general connective tissues, and usually are the most numerous

Macrophage

• Phagocytes that develop from monocytes, a type of white blood cell

• Resting macrophages are confined to a specific tissue (ex. splenic macrophages in spleen)

• Wandering macrophages move throughout body and gather at inflammation sites

Plasmocytes

most plasmocytes reside in connective tissue, especially in the digestive canal and respiratory tracts; secrete antibodies

Mast cells

react to injury or infection, involved in inflammation response, ingest and kill bacteria

Adipocytes

fat cells, store triglycerides; found deep to skin and around organs

Leukocytes

migrate from blood into connective tissue to sites of infection or allergic responses

-blast

• immature cell

• increased cell divisions

• secrete extracellular matrix

-cyte

• mature cell

• decreased cell divisions

• maintain extracellular matrix

extracellular matrix

material between connective tissue cells, contains protein fibers and ground substance

ground substance

• medium between cells and fibers

• includes polysaccharides and proteins (hyaluronic acid - lubrication, keratin - support and adhesiveness, proteoglycans - core protein, etc.)

• varies in consistency

fibers

• collagen: strength and elasticity

• elastic: stretch and return to normal

• reticular: support and strength (collagen in bundles)

Mesenchyme

• irregularly shaped mesenchymal cells embedded in semifluid ground substance that contains delicate reticular fibers

• Location: under skin and along developing bones of embryo; some in adult connective tissue, especially along blood vessels

• Function: Forms almost all other types of connective tissue

Mucoid connective tissue

• jellylike ground substance

• Location: umbilical cord of fetus

• Function: support

Loose connective tissue

loosely arranged between cells

Dense connective tissue

Densely packed but fewer cells