1. Tissue Introduction & Epithelial Tissue Physiology

2. Cells to Tissues As human body develops from single to multicellular, cells specialize. As human body develops from single to multicellular, cells specialize. Body is interdependent system, malfunction of one group of cells is catastrophic. Body is interdependent system, malfunction of one group of cells is catastrophic. Cells specialize into types of tissues, then interspersed into organs. Cells specialize into types of tissues, then interspersed into organs.

3. Tissues = groups of cells that are similar in structure and function. Epithelium Epithelium Coverings Coverings Linings of surfaces Linings of surfaces Connective Connective Support Support Bone, ligaments, fat Bone, ligaments, fat Muscle Muscle Movement Nervous Nervous Control Brain, nerves, spinal cord

4. Function of Epithelial Tissue Protection Protection Skin protects from sunlight & bacteria & physical damage. Skin protects from sunlight & bacteria & physical damage. Absorption Absorption Lining of small intestine, absorbing nutrients into blood Lining of small intestine, absorbing nutrients into blood Filtration Filtration Lining of Kidney tubules filtering wastes from blood plasma Lining of Kidney tubules filtering wastes from blood plasma Secretion Secretion Different glands produce perspiration, oil, digestive enzymes and mucus Different glands produce perspiration, oil, digestive enzymes and mucus

5. Characteristics of Epithelial Tissue Form continuous sheets (fit like tiles) Form continuous sheets (fit like tiles) Apical Surface Apical Surface All epithelial cells have a top surface that borders an open space – known as a lumen All epithelial cells have a top surface that borders an open space – known as a lumen Basement Membrane Basement Membrane Underside of all epithelial cells which anchors them to connective tissue Underside of all epithelial cells which anchors them to connective tissue Avascularity (a = without) Avascularity (a = without) Lacks blood vessels Lacks blood vessels Nourished by connective tissue Nourished by connective tissue Regenerate & repair quickly Regenerate & repair quickly

6. Classification of Epithelial Tissue Cell Shape Cell Shape Squamous – flattened like fish scales Squamous – flattened like fish scales Cuboidal - cubes Cuboidal - cubes Columnar - columns Columnar - columns Cell Layers Cell Layers Simple (one layer) Simple (one layer) Stratified (many layers) Stratified (many layers) Named for the type of cell at the apical surface. Named for the type of cell at the apical surface.

7. Simple Squamous Epithelium Structure Structure Single Layer of flattened cells Single Layer of flattened cells Function Function Absorption, and filtration Absorption, and filtration Not effective protection – single layer of cells. Not effective protection – single layer of cells. Location Location Walls of capillaries, air sacs in lungs Walls of capillaries, air sacs in lungs Form serous membranes in body cavity Form serous membranes in body cavity

9. Simple Cuboidal Epithelium Structure Structure Single layer of cube shaped cells Single layer of cube shaped cells Function Function Secretion and transportation in glands, filtration in kidneys Secretion and transportation in glands, filtration in kidneys Location Location Glands and ducts (pancreas & salivary), kidney tubules, covers ovaries Glands and ducts (pancreas & salivary), kidney tubules, covers ovaries

11. Simple Columnar Epithelium Structure Structure Elongated layer of cells with nuclei at same level Elongated layer of cells with nuclei at same level Function Function Absorption, Protection & Secretion Absorption, Protection & Secretion When open to body cavities – called mucous membranes When open to body cavities – called mucous membranes Special Features Special Features Microvilli, bumpy extension of apical surface, increase surface area and absorption rate. Microvilli, bumpy extension of apical surface, increase surface area and absorption rate. Goblet cells, single cell glands, produce protective mucus. Goblet cells, single cell glands, produce protective mucus. Location Location Linings of entire digestive tract Linings of entire digestive tract

13. Pseudostratified Epithelium Structure Structure Irregularly shaped cells with nuclei at different levels – appear stratified, but aren’t. Irregularly shaped cells with nuclei at different levels – appear stratified, but aren’t. All cells reach basement membrane All cells reach basement membrane Function Function Absorption and Secretion Absorption and Secretion Goblet cells produce mucus Goblet cells produce mucus Cilia (larger than microvilli) sweep mucus Cilia (larger than microvilli) sweep mucus Location Location Respiratory Linings & Reproductive tract Respiratory Linings & Reproductive tract

14. Cilia Basement Membrane

15. Stratified Squamous Epithelium Structure Structure Many layers (usually cubodial/columnar at bottom and squamous at top) Many layers (usually cubodial/columnar at bottom and squamous at top) Function Function Protection Protection Keratin (protein) is accumulated in older cells near the surface – waterproofs and toughens skin. Keratin (protein) is accumulated in older cells near the surface – waterproofs and toughens skin. Location Location Skin (keratinized), mouth & throat Skin (keratinized), mouth & throat

16. Keratin Stratified Cubodial (layers of cubodial only)

17. Transitional Epithelium Structure Structure Many layers Many layers Very specialized – cells at base are cuboidal or columnar, at surface will vary. Very specialized – cells at base are cuboidal or columnar, at surface will vary. Change between stratified & simple as tissue is stretched out. Change between stratified & simple as tissue is stretched out. Function Function Allows stretching (change size) Allows stretching (change size) Location Location Urinary bladder, ureters & urethra Urinary bladder, ureters & urethra

19. Glands One or more cells that make and secrete a product. One or more cells that make and secrete a product. Secretion = protein in aqueous solution: hormones, acids, oils. Secretion = protein in aqueous solution: hormones, acids, oils. Endocrine glands Endocrine glands No duct, release secretion into blood vessels No duct, release secretion into blood vessels Often hormones Often hormones Thyroid, adrenal and pituitary glands Thyroid, adrenal and pituitary glands Exocrine glands Exocrine glands Contain ducts, empty onto epithelial surface Contain ducts, empty onto epithelial surface Sweat, Oil glands, Salivary glands, Mammary glands. Sweat, Oil glands, Salivary glands, Mammary glands.

20. Shapes of Exocrine glands  Branching  Simple – single, unbranched duct  Compound – branched.  Shape:tubular or alveolar  Tubular – shaped like a tube  Alveolar – shaped like flasks or sacs  Tubuloalveolar – has both tubes and sacs in gland

22. Modes of Secretion (How the gland’s product is released) (How the gland’s product is released) Merocrine Merocrine Just released by exocytosis without altering the gland at all. Just released by exocytosis without altering the gland at all. Ex: Sweat glands and salivary glands Ex: Sweat glands and salivary glands Holocrine Holocrine The gland ruptures and releases secretion and dead cells as well. The gland ruptures and releases secretion and dead cells as well. Sebaceous (oil glands on the face) only example Sebaceous (oil glands on the face) only example