epithelial tissue 2023-25.pdf

 Histology Tissues similar functions morphology Epithelial tissue Connective tissue Muscular tissue Nervous tissue Epithelial tissue Connective tissue Muscular tissue Nervous tissue TISSUE CELLS EXTRACELLULAR MAIN FUNCTIONS...

 Histology Tissues similar functions morphology Epithelial tissue Connective tissue Muscular tissue Nervous tissue Epithelial tissue Connective tissue Muscular tissue Nervous tissue TISSUE CELLS EXTRACELLULAR MAIN FUNCTIONS MATRIX EPITHELIAL Aggregated polyhedral Small amount Lining of surface or cells body cavities; glandular secretion CONNECTIVE Several types of fixed and Abundant amount Support and wandering cells protection of tissues/organ MUSCLE Elongated contractile Moderate amount Strong contraction; cells body movements NERVOUS Elongated with extremely Very small amount Transmission of fine processes nerve impulses Epithelial Tissue epithelial cells closely adherent extremely cohesive AVASCULAR tissues AVASCULAR - small capillary cannot pass the basal membrane basement membrane or basal lamina Provides structural support for the epithelium and serves as a selective barrier for the movement of materials to and from the supporting tissue.  derived 3 germ layers Ectoderm Mesoderm Endoderm  II: FUNCTIONS Remember…  III – CLASSIFICATION: Covering / Surface epithelium Glandular epithelium  Number of cell layer/s Shape optional; if with special feature  NUMBER of cell layer/s 4 subtypes Simple - 1 LAYER Stratified - SEVERAL LAYERS Pseudostratified -EPITHELIUM SIMPLE Transitional-SHAPE EPITHELIAL CHANGE IN  single layer of cells Simple squamous Simple cuboidal Simple columnar  SIMPLE SQUAMOUS EX: KIDNEYS, ALVEOLI AND CORNEAL EPITHELIUM Well – adapted for exchange and filtration purposes They provide little protection against mechanical abrasion  Parietal layer of Bowman’s Capsule Simple Squamous MESOTHELIUM  Simple Cuboidal lines small ducts and tubules that may have excretory, secretory or absorptive functions  Simple Columnar Absorptive surfaces such as in the small intestine Secretory surfaces such as that of the stomach  - RAPIDLY DIVIDING several layers of cells protective barrier Stratified cuboidal- Stratified columnar- excretory ducts of Conjunctiva lining the eyelids salivary and sweat glands  Stratified epithelium contains cells that are flattened and cells that are cuboidal UROEPITHELIUM  Respiratory epithelium Pseudostratified Columnar Ciliated with Goblet cell simple epithelium False stratification Cilia are never present on TRUE stratified epithelia MICROVILLI apical surface absorptive cells striated / brush border appearance; INCREASE the cell’s surface area CILIA STEREOCILIA CILIA STEREOCILIA MICROVILLI Short numerous containing arrays of Numerous thin membrane extensions microfilaments and membrane fold supported by microtubules actin-binding proteins, projecting from the free cell surface: supported by microfilaments Move substances over cell increase the cells’ surface Increase membrane surface area, facilitating surface area for greater absorption absorption INTERCELLULAR JUNCTIONS  CYTOSKELETON SITE Functions/ Examples Zonula adherens Actin filaments Lateral plasma Link cytoskeleton to (Adhering belt) Microtubules membrane adjacent cells/ Immediately Intercalated disc or deep to tight cardiac muscle junction Macula Adherens Intermediate filaments Lateral plasma Link cytoskeleton to (Desmosome) membrane adjacent cells/ Keratins in epithelial cells Hemidesmosomes Intermediate filaments Basal plasma Links cells to membrane underlying basement membrane  important in the control of growth, development, cell recognition and differentiation. provide the means of electrical coupling of visceral and cardiac muscle cells, permitting synchronous contraction  CLASSIFICATION – SUBTYPE SPECIFIC SUBTYPE  Number of cell layer/s Shape optional; if with special feature Ileum Kidney PCT DCT Urinary Bladder A 40 y/o man has a history of smoking. He complains of mucus accumulation and constant cough. A biopsy reveals that the epithelial lining of the tracheal lumen is stratified squamous epithelium. METAPLASIA  CARCINOMA SQUAMOUS CELL CARCINOMA GLANDULAR EPITHELIUM w/o connection, hormones A B C D E  NUMBER single secreting cell Duct Goblet cell Secretory unit MANNER FATE TYPE TYPE OF SECRETION (Exocrine glands with MEROCRINE secretion) SEROUS MUCOUS MI XED Mucous and serous Heavy glycosylated (mucin) (component) WATER (stain) MORPHOLOGY  Morphology Simple Compound  Simple Simple tubular Simple coiled tubular Simple branched tubular  Simple acinar (simple alveolar) Simple branched alveolar (simple branched acinar)  Compound Compound tubular  Compound tubulo-alveolar (compound tubulo- acinar) Compound alveolar  ADENOMA ADENOCARCINOMA THANK YOU…