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EPITHELIAL TISSUE

EPITHELIAL TISSUE. Tissue - group of cells with similar structure and function. 4 types Epithelial Connective Muscular Nervous Organs contain several tissue types Arrangement determines structure and function. Epithelial Tissue or epithelium.

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EPITHELIAL TISSUE

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  1. EPITHELIAL TISSUE

  2. Tissue - group of cells with similar structure and function • 4 types • Epithelial • Connective • Muscular • Nervous • Organs contain several tissue types • Arrangement determines structure and function

  3. Epithelial Tissue or epithelium • Consists of cells with little extracellular fluid between them • Covers body surfaces, lines body cavities, hollow organs, and ducts, and forms glands • Functions: protection, absorption, filtration, secretion

  4. Cells fit very closely together to form a continuous sheet Cells held together by cell junctions ( true for epithelial cells, some muscles and nerve cells) Apical surface Basement membrane Avascular Has a nerve supply High capacity for renewal by cell division Special Characteristics

  5. CELL SHAPE Squamous (SKWA mus) Cuboidal columnar CELL ARRANGEMENT Simple stratified Classification of epithelial tissue

  6. TYPES OF EPITHELIAL • Simple squamous • Simple cuboidal epithelium • Simple columnar • Pseudostratified columnar / pseudostratified ciliated columnar • Stratified squamous epithelium • Stratified cuboidal / columnar • Transitional eipthelium

  7. SIMPLE SQUAMOUS • Thin single layer • Rests on basement membrane • Functions: filtration, exchange • Location: walls of capillaries, air sacs • Forms serous (SIR –us) membranes

  8. SIMPLE CUBOIDAL • Single layer • Function: secretion and absorption • Found in glands and their ducts • Ex. Salivary glands, • Forms walls of kidney tubules and covers surface of ovaries

  9. SIMPLE COLUMNAR • Single layer of tall cells • Function: protection, secretion, absorption • Location: lines entire digestive tract from stomach to anus, lining of uterus • Contains goblet cells • Forms mucous membranes • Contains microvilli – aid in absorption • Small intestines • Some may be ciliated

  10. PSEUDOSTRATIFIED COLUMNAR • Cells are of different heights • Cell nuclei are of different lengths • Function: absorption, excretion

  11. Pseudostratified ciliated columnar • Lines respiratory tract • Mucus traps small debris • Cilia propel the mucus upward • Move oocytes through the uterine tubes

  12. STRATIFIED • Two or more cell layers • Names for the type of cells at the apical layer • FUNCTION: protection of underlying tissues in areas where there is considerable wear and tear.

  13. STRATIFIED SQUAMOUS Most common of the stratified Apical area is squamous cells Basement area is cuboidal or columnar Function: protection Found in high friction areas

  14. STRATIFIED CUBOIDAL / COLUMNAR • Rare in body • Found mainly in ducts of large glands

  15. TRANSITIONAL EIPTHELIUM • Found in the lining of the urinary bladder, ureters, and part of the urethra • Tissue can stretch

  16. Glandular Epithelium • Makes up glands • The cells in the glands produce a secretion

  17. ENDOCRINE Secretion is released into the blood stream ductless Examples - pituitary, thymus, pineal, thyroid EXOCRINE Secretion is released through a duct on to the body’s surface or into hollow organ Most numerous Goblet cells Examples – sweat/oil glands, glands that make digestive enzymes, mammary glands TWO TYPES

  18. CELL CONNECTIONS • Adhesion junction • Tight junction • Gap junction

  19. CELL MEMBRANE CONTINUED • Plasma membrane • Short chains of sugars • plycoproteins • glycolipids • Cell identity markers

  20. BODY MEMBRANES • Epithelial membranes • cutaneous membrane - skin • mucous membrane • serous membrane • Connective tissue membranes • synovial membranes

  21. MUCOUS MEMBRANES • Composed of epithelium tissue • lines all body cavities that open to the exterior • stratified squamous • simple columnar • continuously bathed in secretions (mucous) • except urinary mucosae - urine

  22. MUCOUS MEMBRANES CONTINUED • Functions • Protection • Traps dust • Prevents destruction of stomach lining by acid • lubrication • can be modified for absorption or secretion

  23. SEROUS MEMBRANES • Simple squamous epithelium on a layer of connective tissue • Lines body cavities that do not open to the exterior • occurs in pairs

  24. PAIRS OF SEROUS MEMBRANES • Parietal • Visceral • Serous fluid • Names • peritoneum • pleura • pericardium

  25. Internet sites • Internet Atlas of Histology • www.med.uiuc.edu/histo/small/atlas/ • JayDoc • kumc.edu/instruction/medicine/anatomy/histoweb/ • Lumen Histology • Meddean.luc.edu/lumen/MedEd/Histo/frames/histo_frames

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