Tissue Types in the Human • Epithelial • Primarily used for protection • Very little extracellular material between cells • Endothelium: specialized epithelial cells in blood vessels • Connective • Primarily used for support • Nerve • Primarily used for control • Muscle • Primarily used for movementEpithelial Tissue • Cells are polyhedral (many sided) with little interstitial space • Covers the outermost layer of the skin • Covers innermost layer of most organs and cavities • Lungs, GI tract, Urinary tracts, Reproductive tracts, • One side always exposed to: • Body exterior http://www.britannica.com/EBchecked/topic/190379/epithelium • Organ tract or cavity • Makes up the exocrine and endocrine glands • Exocrine (“excreting”): sweat glands, digestive glands, mammary glands • Endocrine (“hormones”): thyroid, pancreas, adrenal cortex • Cells have high regeneration potential but are avascular • Rely on perfusion for O2 supply • Many epithelial cells rest on a “Basement Membrane” • Basement Membrane = Basal Lamina (2 layers) + Reticular Lamina • Basal Lamina: flat “sheets” of nonliving adhesive-like collagen and glycoprotein • secreted by the epithelial cells themselves • Reticular Lamina: “foundation” for the Basal LaminaThree layer structure of the “Basement Membrane” (Hemidesmosomes function in cell signaling for things such as proliferation & apoptosis) Basement Membrane = Basal Lamina + Reticular LaminaAdjectives Describing Epithelial Tissue Simple - having a single layer of cells Squamous (meaning “scale”) - flat cells Cuboidal - cells as tall as they are wide Columnar - tall and column shaped Stratified - having stacked layers Transitional – “dome” surface cells - capable of stretching (bladder) Ciliated - cilia on the exposed surface Examples you should remember: • SIMPLE SQUAMOUS EPITHELIUM • Permeable cell structure - used for filtration and gas exchange • Examples: capillaries, alveoli, kidney glomeruli • STRATIFIED SQUAMOUS EPITHELIUM • Used for “protection” • Examples: skin, inside of mouth, vagina • CILIATED COLUMNAR EPITHELIUM • Used to move substances along a particular direction using the cilia • Examples: upper respiratory tract, fallopian tubes Simple Squamous Simple Cuboidal Simple Columnar Transitional Stratified Squamous Stratified Cuboidal Pseudostratified ColumnarSimple Squamous Epithelium Artery Endothelium Stratified Squamous Epithelium Human Skin Examples of Epithelial Tissue Ciliated Columnar Epithelium Tracheal Lung Tissue • Orange and brown/green covering: Adventicia • Blue: Actin in smooth muscle • Green: Elastic basal membrane (Basil Laminae) • Innermost Orange: Arterial Endothelium Cilia Ciliated Columnar Epithelial CellsDiseases of Epithelial Tissue Simple Squamous Epithelium Arterial Endothelium Dysfunction The Beginnings of Atherosclerosis Ciliated Columnar Epithelium Trachea Tissue from a SMOKER Note Lack of Cilia Note Disorganization of Columnar Epithelial Cells Tear in endothelial wall (injury - dysfunction) Cholesterol crystal deposits Red blood cell Foam cell (Lipid filled macrophages) Fat deposits Monocyte (Macrophage)Connective Tissue • Matrix - “non-living” component of connective tissue • Ground Substance • Proteoglycan aggregates (PGA) - pine tree shaped molecules • Glycosaminoglycans - neg charged binds Na+ & K+ attract H20 • Hyaluronic Acid - negative charged slippery polysaccharride • Condroitin sulfate • Fluid - H2O, gasses, nutrients for cells (H2O facilitates tissue “turgor”) • Minerals - Calcium salts • Adhesive glycoproteins – hold PGA’s together & to membranes • Chondronectin (cartilage), osteonectin (bone), fibronectin (fibrous tissue) Laminin (holds epithelial cells to basement membrane) • Fibers • Collagen, Elastin, and Reticular Fibers • Cells - “living” component of connective tissue • “Blast” Cells, “Cyte” Cells, “Clast” Cells • Macrophages and white blood cells • Mast cells containing Heparin & Histamine • Adipose tissueProteoglycans Electron Micrograph of actual Proteoglycan AggregateTypes of Fibers • Fibrous protein in connective tissue structure • Derived from Greek word meaning “to glue together” • Constitutes about 50% of the proteins in man • Present to some degree in all human organs • Collagen has a finite life span after which it is degraded to the constituent amino acids and replaced by new fibers. • Has high tensile strength: • 4.5 pound load needed to break collagen fiber 1 mm thick Collagen http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mcb.section.6542Collagen FibersEach collagen molecule (also called a tropocollagen) is connected to others via PYRIDINIUM CROSS-LINK BONDS. Collagen Fiber (Fibril) Microfibril A Collagen Molecule (Tropocollagen) Individual Amino Acid Bonds Are Reinforced With Hydrogen Bonds Each chain connected to the other two with Hydrogen Bonds Collagen Structure 3 Alpha Helix Chains Within Each Collagen Molecule Fiber Fibril Microfibril Tropocollagen Helix Collagen Molecule (Tropocollagen) Although Hydrogen bonds are weak, the “stacked intertwined” formation of the triple helix give collagen remarkable strength.Diseases that Affect Collagen Overproduction of Collagen Fibers • Lung Fibrosis (Cystic Fibrosis) – mucous buildup in lungs and pancreas • Caused by a mutation in CTFR gene r product of this gene is ion channel • This channel is important in creating sweat, digestive juices, and mucous • High salt content in sweat is usually present in CF kids – used as a test for CF • Life-span used to be limited to 20-30 years….now possibly 40-50 years • Fibrous obstructions and fluid in lungs r breathing disorders & numerous infections • Fibrous obstructions in pancreas r d digestive enzymes r d nutrient absorption • Malnutrition r d growth http://www.kidshealth.org/kid/health_problems/heart/cystic_fibrosis.html • Liver Cirrhosis – fiber deposition r irreversible scarring in the liver • Common causes: Hepatitis-C Hepatitis-B, alcoholism • Alcohol blocks normal metabolism of protein, fats, and carbs r injury • Cirrhosis r edema & ascites (fluid in peritoneal space) • Liver cannot make Albumin r blood looses osmotic (sucking) pressure • Cirrhosis r u infection