• Found in spaces called lacunae
• Communicate through canaliculi filled with extracellular fluid that connect one cell to the next

• Supports and binds structures together
• material found between cells
• stores energy as fat
• provides immunity to disease (including cells derived from bone marrow)
• develops from mesoderm

• cells shorten in length to produce movement
• cells contract to pump blood and fluids
• cells contract and relax to move diverse substances
• develops from mesoderm

• cells that conduct electrical signals
• detects changes inside and outside the body
• responds with nerve impulses
• develops from ectoderm

develops from all 3 germ layers

(endo-, meso-, and ectoderm)

• Contain plaque, a dense layer of proteins on the inside of the plasma membrane that attaches both to membrane proteins and to microfilaments (actin) of the cytoskeleton
• Found when epithelial cells form sheets
• Integral membrane proteins (cadherins) connect to membranes of other cells

• Contain plaque and have transmembrane glycoproteins (cadherins) that extend into the intercellular space between adjacent cell membranes and attach cells to one another
• Resist cellular separation
• Desmosome plaque attaches to intermediate filaments (micro) of keratin

• Resemble half of a desmosome
• Don't link adjacent cells but anchor cells to the basement membrane
• Attach to keratin microfilaments
• Contains transmembrane glycoproteins integrin
• Connects cells to extracellular material

• Membrane proteins called connexins form tiny fluid-filled tunnels called connexons that connect neighboring cells
• Plasma membrane of gap junctions are separated by a very narrow intercellular gab
• Communication of cells within a tissue
• Ions, nutrients, waste, chemicals and electrical signals travel through the connexons between cells

• Without blood vessels 
• Nutrients diffuse in from underlying connective tissue

• Closely packed cells forming continuous sheets
• Cells sit on basement membrane
• Good nerve supply
• Rapid cell division provides ongoing source of cells
• Variations include covering/lining sheets versus glandular types

• From epithelial tissue
• Basement membrane
• Collagen fibers

• Secreted by connective tissue cells
• Basement membrane
• reticular fibers

• Secreting portion of glands
• Thyroid, adrenal and sweat glands

• single layer of flat cells
• lines blood vessels, body cavities
• very thin
• controls diffusion, osmosis and filtration
• nuclei centrally located
• cells in direct contact with each other

• single layer of cube-shaped cells viewed from the side
• nuclei round and centered
• lines tubes of organs (kidneys)
• designed function is absorption or secretion

• single layer of rectangular cells
• unicellular glands (goblet cells) secrete mucus for lubrication
• contains microvilli or cilia
• cilia moves mucus from goblet cells along

• several cell layers of flat cells
• keratinized - surface of cells are dead and filled with keratin
• nonkeratinized - mouth, vagina

• multilayered
• surface cells cuboidal
• rare...only in sweat gland ducts and male urethra
• functions in protection

• multilayered
• surface more columar
• esophagus

• multilayered
• surface cells vary in shape from round to flat if stretched
• lines hollow organs that expand from within

• single layer
• all cells attach to basement membrane, but not all reach free surface
• nuclei at varying depths
• respiratory system, male urethra and epididymis

• secret sweat, ear wax, saliva, digestive enzymes
• connect to surface organs by tubes (ducts)
• uni- and multicellular glands

• secrete hormones into bloodstream
• hormones help maintain homeostasis

• most exocrine glands
• cells release products by exocytosis - saliva, digestive enzymes and sweat

• Smelly sweat and milk
• Upper part of cell possibly pinches off and dies

• oil gland
• whole cells die and rupture to release their products

• cells rarely touch each other due to extracellular matrix
• matrix secreted by cells
• consistency varies from liquid, gel to solid
• doesn't occur on free surface
• food nerve and blood supply except in cartilage and tendons

cells retain ability to divide and produce matrix

• develop from monocytes
• engulf bacteria and debris by phagocytosis

• develop from B lymphocytes
• produce antibodies that fight against foreign substances

• contains water and many large organic molecules
• hyaluronic - thick, viscous and slippery acid
• condroitin - jelly-like substance providing support
• adhesion protiens - secretions

• tough, resistant to pull, yet pliable
• formed from the protein collagen
• 25% of proteins

• lungs, blood vessls, ear cartilage
• smaller in diameter fibers formed from protein elastin
• can stretch up to 150% of relaxed length and return to original shape

• spleen and lymph nodes
• thin, branched fibers that form framework of organs
• formed from protein collagen

• irregularly shaped cells
• in semifluid ground substance with reticular fibers
• gives rise to all other types of connective tissue

• star-shaped cells in jelly-like ground substance
• found only in umbilical cord

• loose
• all 3 fibers
• most cell types
• subcutaneous layers of skin
• nerves found

• loose
• peripheral nuclei due to fat storage
• energy storage
• heat generations

• network of fibers and cells that produce framework or stroma of organs
• holds organs together

• collagen fibers in parallel bundles with bibroblasts between bundles of collagen fibers
• white, tough, pliable when unstained
• forms tendons, most ligaments, and aponeuroses (large sheet)

• collagen fibers are irregularly arranged
• tissue can resist tension from any direction
• found in fascia around muscles, white of eyeballs, dermis of skin

• branched elastic fibers and fibroblasts
• lung tissue, vocal cords, elastic arteries

cartilage cells found in the spaces called lacunae

• most abundant
• bluish, shiny, white, rubbery substance with fine collagen fibers
• chondrocytes sit in spaces called lacunae
• no blood vessels or nerves
• reduces friction between joints as articular cartilage
• found in ends of long bones, nose, parts of larynx

• many more collagen fibers in bundles causes rigidity and stiffness
• strongest type of cartilage
• found in public symphysis, intervertebral discs

• elastic fibers help maintain shape
• found in ear, nose and vocal
• perichondrium

• chondrocytes divide and form new matrix
• occurs in childhood and adolescence

• along tissue surface
• chondroblasts secrete matirx onto surface
• produces increase in width

• sponge-like with spaces and trabeculae, which are struts of bone surrounded by red bone marrow
• no osteons

• solid and dense
• basic unit of structure is osteon

• lamellae (rings) of mineralized matrix
• calcium and phosphate give its hardness 
• interwoven collagen fibers provide strength

• liquid connective tissue
• provides clotting, immjune functions, and carries oxygen and carbon dioxide
• Cell types:
• RBCs (erythrocytes)
• WBCs (leukocytes)
• cell fragments called plateletes

• lines body cavity that opens to outside (mouth)
• epithelial cells form a barrier to microbes
• tight junctions between cells
• mucous secreted from underlying glands to keep surface moist

• simple squamous cells overlying loose connective tissue layer
• squamous cells secrete slippery fluid
• lines body cavity that doesnt open to outside (chest)

• line joint cavities of all freely movable joints
• no epithelial cells

• cells are long cylinders with many peripheral nuclei
• visible light and dark banding (striated)
• voluntary or conscious control

• cells are branched cylinders with one central nuclei
• involuntary and striated
• attached to and communicate with each other by intercalated discs and desmosomes

• spindle shaped cells with a single central nuclei
• walls of hollow organs (blood vessels, GI tract, bladder)
• involuntary and nonstriated

• replacement with original cell types
• some cell types can and do divide
• some tissues contain stem cells that divide (bone marrow, epithelium of gut and skin)
• some cell types rarely divide and are not readily replaced (muscle and nervoust tissue)

• often forms after surgery or injury
• very active growing connective tissue

• abnormal joining of tissue or membranes
• occurs after surgery or inflamation

• adequate protein for structural components
• vitamin C production of collagen and new blood cells

• stratified squamous epithelium
• contins no blood vessels
• five distinct strata (layers) of cells
• four types of cells:
• keratinocytes
• melanocytes
• langerhans cells
• merkel cells

• 90% of epidermis
• produce keratin

• 8% of epidermis
• produces melanin pigment
• melanin transferred to other cells with long cell processes

• migrate from bone marrow
• paricipate in immunity

• in deepest layer
• form touch receptor with sensory neuron

• 25-30 cells thick
• dead
• barrier

• dividing basal cells
• deepest layer
• merkel cells
• melanocytes
• keratinocytes
• stem cells that divide rapidly

• connective tissue layer composed of collagen and elastic fibers, fibroblasts, macrophages and fat cells
• contains hair follicles, glands, nerves and blood vessles
• papilarry region
• reticular region

• top 20% of dermis
• coposed of loose connective tissue and elastic fibers
• finger like projections called dermal papellae
• functions:
• anchors epidermis to dermis
• contins capillaries that feed epidermis
• contain Meissner's corpuscles (touch) and free nerve endings

• 80% of dermis
• dense irregular connective tissue
• contains interlacing collagen and elastic fibers
• packed with oil glands, sweat gland ducts, fat and hair follicles
• provides strength, extensibility and elasticity to skin
• stretch marks are dermal tears from extreme stretching

• yellow-orange pigment (precursor of vitiman A)
• found in stratum corneum and dermis

• redness of skin due to enlargement of capillaries in dermis
• during inflammation, infection, alleric reaction or burns

• smooth muscle in dermis contracts with cold or fear
• forms goose bumps as hair pulled vertical

• dark hair contains true melanin
• blonde and red hair contain melanin with iron and sulfur
• graying hair is a result of decline in melanin production
• white hair is a result of air bubbles in medullary shaft

• simple, branced acinar glands
• mostly connected to hair follicles
• within dermis

• sudoriferous (sweat) glands
• simple, coiled tubular glands that are much more common than apocrin sweat glands
• opens to surface
• distributed throughout the skin
• cells in gland stay intact

• sudoriferous (sweat) glands
• some of gland cells may be pinched off during secretion (armpit and pubic region)
• opens to hair follicle

• comb of cholesterol, proteins, fats and salts
• sebaceous (oil) glands
• keeps hair and skin soft and pliable
• inhibits growth of bacteria and fungi

• modified sweat glands produce waxy secretion in ear canal
• cerumen contains secretions of oil and wax glands
• helps form barrier for foreign bodies
• impacted cerumen may reduce hearing

• tightly packed keratinized cells
• nail body is pink due to underlying capillaries

• deep to nail root
• region nail growth occurs

• buried under skin layers
• lunula is white due to thickened stratum basale