Tissues 4 types -Nervous – Control and Communicate -Muscle – Movement -Epithelial – Cover and Protect -Connective – Support Nervous tissue Sense stimuli and send impulses -Neurons – Building blocks, generate and conduct impulses -Cell body (Soma) – life support -Dendrites (Listen) – collect signals -Axon (Send) – transmission cable -Glial cells (Pit Crew) – Support, Insulate, Protect and tether neurons to blood vessels Muscle tissue Contract, move, well vascularized -Skeletal – Long, multi-nucleated, parallel with striations -Voluntary – Pull on bones or skin to make you move -Cardiac – Cells divide and converge, one nucleus, striated with intercalated disks -Involuntary – Only in the heart -Intercalated disks – Glue with pores for electrical and chemical signal exchange -Smooth – Short, tapered, one nucleus, NO striations -Involuntary – In hallow organ wall lining Epithelial tissue Regenerate quickly, avascular - relies on blood supply from connective tissue around them -Proper – Separates, Lines, Protects (injury or infection), inside and outside of the “you tube” -Squamous – Make thin membranes, fast absorption and diffusion -Flat cell with flat nucleus -Lungs, Blood vessels -Cuboidal – Absorb nutrients, produce secretions -Cube shaped with round nucleus -Columnar – Cushion underlying tissue -Tall, thick cell with oval (ellipse) nucleus -Stomach lining *Cells are biologically expensive – lots of time, energy, and raw materials to produce* Layering -Simple – One-layer -Stratified – Multiple layers on top of each other -Pseudostratified – Mostly one-layer with cells of different shapes and sizes *First name = number of layers Last name = shape of cells* *Epithelial cells are polar* *Many cell boundaries are selectively permeable – allowing some level of absorption, filtration, and excretion of substances. -Glandular -Endocrine glands – secrete hormones right into the bloodstream and nearby calls -Thyroxine -Exocrine glands – secrete juices into tubes or ducts that lead outside of the body or into a tube -Sweat, saliva, mucous, stomach acid, lactation Connective tissue Functions of connective tissues 1. Bind and support 2. Protect 3. Insulate 4. Store reserve fluid and energy 5. Transport substances 6. Movement All connective tissue has 3 factors in common -Develop from mesenchyme – a loose, fluid, embryonic tissue -Have different degrees of vascularity -Mostly composed of non-living materials called the extracellular matrix *Extracellular Matrix -Ground substance – watery, rubbery, unstructured material that surrounds and protects cells -Made of starch and protein molecules mixed with water -Proteoglycans (protein) with lots of long stringy glycosaminoglycans or GAG (starches) -Look like brush bristles and connect to trap water -Fibers – Provide support and structure -Collagen – strongest, most abundant -Strand of protein – tough and flexible -Elastic – longer, thinner, with branching framework -Elastin – stretch and recoil like a rubber band -skin, lungs, blood vessel walls -Reticular – short, finer, sponge like networks -Collagen with extra coating of glycoprotein *Immature cells = “-blasts” – form and secrete ground substances and fibers to create the unique matrix *Mature cells = “-cytes” – less active, maintain health of the matrix, can convert back to “-blasts” to repair/generate new matrix -Macrophages – (guard cells) patrol connective tissue eating bacteria, foreign material, etc. -Leukocytes – WBC’s -Connective tissue proper -Loose -Dense -Areolar -Regular -Reticular -Irregular -Adipose -Elastic -Loose – More ground substance, fewer fibers, elastin = recoil collagen = anchoring -Areolar – Loose, random arrangement of fibers with few fibroblasts -Lots of open space under the microscope -Good at holding watery, salty ground substance = edema -Just under epithelial tissue and around organs -Adipose = fat tissue – mostly cells -Adipocytes – store lipids, insulate body from heat loss -Reticular – Like areolar with loose woven mass of reticular fibers -Provided soft internal framework (stroma) -Supports developing blood cells and holds blood in place in many organs -Spleen, lymph nodes, bone marrow -Dense – A lot more collagen -Regular – Collagen bundles all running parallel -Provide great resistance to tension when tension exerted in one direction -Tendons – muscle to bone or muscle to muscle -Ligaments – bone to bone -Irregular – Collagen fibers are thicker and arranged erratically -Provide resistance when tension exerted in multiple directions -Leathery Dermis – under the skin -Elastic – More elasticity than rigidity -Around vertebrae and joints -Largest artery walls – support and elasticity Cartilage – No blood, no nerves, holds up to tension and compression -Hyaline – glassy looking, ground substrate rich in proteoglycans -Pliable support -Connects ribs to sternum -Elastic – like hyaline but more elastic fibers that are easier to see -Strength and stretchability -Ears -Fibro – Thick collagen fibers -Impact resistant -Keep bones from grinding -Vertebral disks, knee joint Bone – Calcified connective tissue -Spongy – Strong, porous -Makes and stores bone marrow -Head of long bones -Inner layer of flat bones (sternum, ileus) -Compact – Dense with no visible spaces -Stores calcium for bones to make more tissue -External layer of bones Blood – ground substance = plasma with protein fibers floating around -Protein in plasma will form fiber like structures when blood needs to clot -Erythrocytes – RBC’s – Oxygen and carbon dioxide transport -Leukocytes – WBC’s – Larger and fight infection -Platelets – Call fragments used to create blood clots
