Epithelial and Connective Tissues • Classes of Tissues • Two classes—epithelial, connective • Muscle and Nervous Tissue (don’t fit in classes) • Epithelial tissues • General characteristics • Cell shapes • Connective Tissues • General characteristics (areolar) • Types of connective tissues Human Anatomy, Larry M. Frolich, Ph.D.
General Types of Tissues Tissue: a group of closely associated cells that have a similar structure and perform a related function • Broad Classes of Tissues • -Epithelial: sheet of cells. • -Connective: cells in a matrix • More specific tissue types • -do not fit as epithelial or connective • -will treat in section two of course • -Nervous: carries messages in body • -Muscle: effects movement • Virtually all organs will have all four types Human Anatomy, Larry M. Frolich, Ph.D.
Epithelial Tissues • Cells connect, on their lateral surfaces, forming sheets • Gap junctions • Tight junctions • desmosomes • Cells can have appendages, on their apical surface, to interact with environment • Cilia • Microvili • Flagella • Cells sit, on their basal surface, on a thin basal membrane of collagen fibers for support • Underlying connective tissue further supports epithelium • Blood vessels/nerves travel in underlying connective tissue, nerve endings on epithelium Examples of epithelium: epidermis, lining of gut, mucous membranes, lining of celom, glands Human Anatomy, Larry M. Frolich, Ph.D.
Appendages on apical surface • Microvilli: (ex) in small intestine • Finger-like extensions of the plasma membrane of apical epithelial cell • Increase surface area for absorption • Cilia: (ex) respiratory tubes • Whip-like, motile extensions • Moves mucus, etc. over epithelial surface 1-way • Flagella: (ex) spermatoza • Extra long cilia • Moves cell Cilia in tracheaa Human Anatomy, Larry M. Frolich, Ph.D.
Connections between epithelial cells • Desmosome: binding spots between cells with proteins called cadherins • Tight junctions: impermeable • E.g. gut tube, doesn’t let enzymes from gut into blood stream • Gap junctions: tubes that let small molecules pass between cells Human Anatomy, Larry M. Frolich, Ph.D.
Name that Epithelial Feature!(name and location on cell) 3 • Cilia • Tight junction • Microvilli • Basement membrane 3 1 1 2 2 4 4 Human Anatomy, Larry M. Frolich, Ph.D.
Simple: just one layer or cell shape Stratified: multiple layers and cell shapes Classes of Epithelia Human Anatomy, Larry M. Frolich, Ph.D.
Simple Epithelia Simple squamous epithelium from alveolus of lung Human Anatomy, Larry M. Frolich, Ph.D.
Squamous E.g. epidermis Transitional epithelium E.g. urinary structures--bladder Stretches from 6 cells to 3 cells thick as bladder fills and expands Stratified Epithelia Human Anatomy, Larry M. Frolich, Ph.D.
Quiz!! E Can You Identify the Classes of Epithelium? D A B C Human Anatomy, Larry M. Frolich, Ph.D.
Glands: epithelial cells that make and secrete a water-based substance • Exocrine Glands • Secrete substance onto body surface or into body cavity • Have ducts • E.G., salivary, mammary, pancreas, liver • Endocrine Glands • Secrete product into blood stream • Either stored in secretory cells or in follicle surrounded by secretory cells • Hormones travel to target organ to increase response • No ducts Human Anatomy, Larry M. Frolich, Ph.D.
CONNECTIVE TISSUES • “Areolar tissue” as model • Universal in body • Underlies epithelium, supports capillaries, small nn. • Always originates from mesenchyme • CELLS in MATRIX Human Anatomy, Larry M. Frolich, Ph.D.
Extracellular matrix • Fibers • Collagen gives structure • Reticular fibers (crossed collagen) gives order • Elastin gives elasticity • Ground substance • Jelly-like material made of sugar-protein molecules (proteoglycans) Human Anatomy, Larry M. Frolich, Ph.D.
Cells of Connective Tissues • Fibroblasts make fibers • Immune cells in areolar tissue • Macrophages • Plasma cells • Mast cells • Neutrophils, Lymphocytes Human Anatomy, Larry M. Frolich, Ph.D.
Areolar connective tissue Human Anatomy, Larry M. Frolich, Ph.D.
“Loose” connective tissues • Adipose tissue mostly under skin and in mesenteries • Reticular: organized 3-D network of fibers that support lots of cells • E.g. marrow, spleen, lymph nodes Human Anatomy, Larry M. Frolich, Ph.D.
“Dense” Connective tissues • Irregular • Thick fibers running in many planes • E.g. dermis, fibrous capsules around organs • Regular • Aligned parallel fibers • Resists tension • E.g. tendon, ligaments, aponeuroses • Sometimes with elastic fibers (e.g. ligamentum nuchae) Human Anatomy, Larry M. Frolich, Ph.D.
Other Connective Tissues • Bone • Cartilage • Blood Human Anatomy, Larry M. Frolich, Ph.D.