1. TISSUES

2. TEAMWORK The human body contains about 100 trillion cells. However, no one cell can carry out all the necessary bodily functions by itself. So, cells aggregate and form TISSUES Tissue  Collection of cells with a similar structure and function. The study of tissues is known as HISTOLOGY

3. EPITHELIUM Covers the surface of the body, lines the body cavities, forms the external and internal linings of most organs, and constitutes the bulk of most glands (glandular epithelium) Functions include: 1.Protection 4. Absorption 2.Secretion5. Filtration 3.Sensory reception On the right we have a section of skin. Where would the bulk of the epithelial tissue be found?

4. INTERCELLULAR CONNECTIONS Close packing of epithelial cells, attached to basement membrane –Effective barrier Tight junctions –Common in lining of stomach and intestines WHY? Desmosome –Common in Epidermis  WHY? Gap Junction

5. GLANDULAR EPITHELIUM A gland is one or more cells that makes and secretes an aqueous fluid Two types of glands formed by in-folding of epithelium: –Endocrine –Exocrine Exocrine glands classified either by structure or by the method of secretion Classified by structure –Unicellular: goblet cells –Multicellular: sweat, oil, pituitary, adrenal

6. MODE OF SECRETION Merocrine – most glands (salivary, sweat, pancreatic) Apocrine – mammary glands Holocrine – sebaceous glands https://embryology.med.unsw.edu.au/embryology/images/e/ed/Merocrine_secretion_animation.gif https://embryology.med.unsw.edu.au/embryology/images/8/8f/Apocrine_secretion_animation.gif https://embryology.med.unsw.edu.au/embryology/images/6/6e/Holocrine_secretion_animation.gif http://wps.aw.com/wps/media/objects/443/453803/st0401.html

7. MEMBRANES Epithelial tissues with an underlying connective tissue support, which all provide some type of secretion 1.Basement membrane 2.Mucous 3.Serous 4.Cutaneous 5.Synovial (connective mostly)

8. Here, we have pathogens traveling down the pharynx trying to attack the surface cells. How can they be repelled???

9. The mucosal cells lining the trachea have released a flood of mucus, trapping the pathogens!

10. The cilia successfully sweep the pathogens up and away!

11. CILIA In the respiratory tract there are lots of mucus-secreting goblet cells. –The mucus traps dust and bacteria Cilia in respiratory epithelium “sweep” bacteria-laden mucus up the respiratory tract towards the pharynx where it can be swallowed –Smoking paralyzes cilia (harsh cough)

12. CONNECTIVE CELLS & FIBERS

13. HISTOPATHOLOGY Microscopic examination of biological tissues to observe the appearance of diseased cells and tissues

14. TISSUES & AGING Injury requires restoration of homeostasis –Inflammation –Regeneration Fibrosis

15. TISSUE DISEASES Menkes Syndrome – neurodegenerative disease, kinky hair, weak muscles Connective Tissue disorders –Marfan Syndrome – systemic; tall, long bones, “spider-like” fingers & toes –Ehlers-Danlos syndrome (EDS) – over-flexible joints, stretchy skin –Epidermolysis Bullosa (EB) – fragile skin, tears and blisters