Tissue Level of Organization

1. Tissue Level of Organization Dr. Michael P. Gillespie

2. Tissue Types • Four basic tissue types exist in the body. • 1. Epithelial tissue • 2. Connective tissue • 3. Muscle tissue • 4. Nervous tissue Dr. Michael P. Gillespie

3. Epithelial Tissue • Epithelial tissue covers body surfaces and lines hollow organs, body cavities, and ducts. It also forms glands. Dr. Michael P. Gillespie

4. Connective Tissue • Connective tissue protects and supports the body and its organs. Various types of connective tissue bind organs together, store energy reserves as fat, and help provide immunity to disease-causing organisms. Dr. Michael P. Gillespie

5. Muscle Tissue • Muscle tissue generates the physical force needed to make body structures move. Dr. Michael P. Gillespie

6. Nervous Tissue • Nervous tissue detects changes in a variety of conditions inside and outside the body and responds by generating nerve impulses and help maintain homeostasis. Dr. Michael P. Gillespie

7. Biopsy • A biopsy (bio = life, -opsy = to view) is the removal of a sample of living tissue for microscopic examination. • Used to diagnose disorders. • Compared to normal tissue. • Removed surgically or through needle and syringe. Dr. Michael P. Gillespie

8. Cell Junctions • Cell junctions are contact points between the plasma membranes of tissue cells. • Functions • Forming seals between cells. • Anchoring cells to one another or to extracellular material. • Channels between cells in a tissue (passage of ions and molecules). Dr. Michael P. Gillespie

9. Dr. Michael P. Gillespie

10. Major Types of Cell Junctions • Tight junctions • Adherens junctions • Desmosomes • Hemidesmosomes • Gap junctions Dr. Michael P. Gillespie

11. Adherens Junctions • Help epithelial cells resist separation. • Located in epithelial cells. Dr. Michael P. Gillespie

12. Desmosomes • Attach cells to one another. • Contribute to the stability of the cells and tissue. • Found in the epidermis and between cardiac muscle cells. Dr. Michael P. Gillespie

13. Hemidesmosomes • Hemi – half. Hemidesmosomes lack links to adjacent cells. • Anchor cells to the basement membrane. Dr. Michael P. Gillespie

14. Gap Junctions • Form fluid filled channels that connect adjacent cells. • Ions and small molecules can diffuse from the cytosol of one cell to the next. • Enable nerve impulses to travel more rapidly among cells. Dr. Michael P. Gillespie

15. Epithelial Tissue • Cells arranged in continuous sheets. • Avascular – without blood vessels. • Exchange of substances occurs by diffusion. Dr. Michael P. Gillespie

16. Apical Surface • Apical (free) surface – faces the body surface, a body cavity, the lumen (interior space) of an internal organ, or a tubular duct that receives secretions from cells. Dr. Michael P. Gillespie

17. Lateral Surfaces • The lateral surfaces of an epithelial cell face adjacent cells. • The lateral surfaces may contain tight junctions, adherens junctions, desmosomes, and gap junctions. Dr. Michael P. Gillespie

18. Basal Surface • Opposite the apical surface. • Anchored to the basement membrane. Dr. Michael P. Gillespie

19. Basement Membrane • Attaches to and supports the epithelial layer. • Restricts the passage of larger molecules between the epithelial layer and connective tissue. Dr. Michael P. Gillespie

20. Dr. Michael P. Gillespie

21. Types of Epithelium • Covering and lining epithelium • Forms the outer covering of skin and some internal organs. • Forms the lining of blood vessels, ducts, body cavities, and the interior of the respiratory, digestive, urinary, and reproductive systems. • Glandular epithelium • Forms the secreting portion of glands (I.e. thyroid, adrenal and sweat glands). Dr. Michael P. Gillespie

22. Classification of Epithelium • Classified by the # of layers. • Classified by the shapes of cells. Dr. Michael P. Gillespie

23. Arrangement of Cells in Layers • Simple epithelium - single layer of cells • Functions in secretion and absorption • Stratified epithelium – 2 or more layers of cells • Protects underlying tissues • Pseudostratified epithelium – contains a single layer of cells, but the nuclei lie at different levels. • Some cells are ciliated or secrete mucus. Dr. Michael P. Gillespie

24. Cell Shapes • Squamous cells • Flat, thin cells that allow for rapid movement of substances through them. • Cuboidal cells • As tall as they are wide. Function in secretion or absorption. May have microvilli. • Columnar cells • Taller than they are wide. Specialized for secretion or absorption. • Transitional cells • Change shape as organs stretch and collapse. Dr. Michael P. Gillespie

25. Types of Simple Epithelium • Simple squamous epithelium • Simple cuboidal epithelium • Simple columnar epithelium • Nonciliated • Ciliated Dr. Michael P. Gillespie

26. Types of Stratified Epithelium • Stratified squamous epithelium • Keratinized • Nonkeratinized • Stratified cuboidal epithelium • Stratified columnar epithelium • Transitional epithelium Dr. Michael P. Gillespie

27. Pseudostratified Columnar Epithelium • Nonciliated • Ciliated Dr. Michael P. Gillespie

28. Simple Squamous Epithelium • Single layer cells. • Flat cells. • Location • Bowman’s capsule of kidneys • Air sacs of lungs • Lining of the heart • Lining of blood vessels • Lining of lymphatic vessels • Inner surface of the tympanic membrane Dr. Michael P. Gillespie

29. Dr. Michael P. Gillespie

30. Simple Cuboidal Epithelium • Single layer of cells. • Cells have an equal height and width. • Functions of secretion and absorption. • Location • Surface of ovary • Kidney tubules • Ducts of many glands • Secreting portions of some glands Dr. Michael P. Gillespie

31. Dr. Michael P. Gillespie

32. Simple Columnar Epithelium • Single layer of cells. • Cells are taller than they are wide. • Location • Ciliated • Upper respiratory tract • Uterine (Fallopian) tubes • Paranasal sinuses • Central canal of spinal cord • Nonciliated • GI tract from stomach to anus • Ducts of many galnds • Gallbladder Dr. Michael P. Gillespie

33. Dr. Michael P. Gillespie

34. Stratified Squamous Epithelium • 2 or more layers of cells • Apical layers of cells are flat • Deep layers vary in shape from cuboidal to columnar • Keratinized and nonkeratinized forms • Location • Keratinized lines the surface of the skin • Nonkeratinized lines wet surfaces such as the mouth, esophagus, epiglottis, vagina and tongue Dr. Michael P. Gillespie

35. Dr. Michael P. Gillespie

36. Stratified Cuboidal Epithelium • 2 or more layers of cells • Equal in height and width • Location • Ducts of adult sweat glands and esophageal glands • Part of male urethra Dr. Michael P. Gillespie

37. Dr. Michael P. Gillespie

38. Stratified Columnar Epithelium • 2 or more layers of cells • Taller than they are wide • Basal layer contains shortened, irregularly shaped cells • Only the apical layer has columnar cells • Location • Part of urethra • Excretory ducts of some glands (I.e. esophageal) • Anal mucous membrane • Conjunctiva of the eye Dr. Michael P. Gillespie

39. Dr. Michael P. Gillespie

40. Transitional Epithelium • 2 or more layers of cells • Variable in appearance • Present in the urinary system • Un-stretched it looks similar to stratified cuboidal epithelium • Stretched it looks similar to stratified squamous epithelium • Location • Urinary bladder • Portions of the ureters and urethra Dr. Michael P. Gillespie

41. Dr. Michael P. Gillespie

42. Pseudostratified Columnar Epithelium • Single layer of cells – appears to be more than one layer due to uneven nuclei • Some cells do not extend to the surface • The cells that extend to the surface either secrete mucous (goblet cells) or bear cilia • Location • Airways of the upper respiratory tract • Larger ducts of many glands • Epididymis • Part of male urethra Dr. Michael P. Gillespie

43. Dr. Michael P. Gillespie

44. Glandular Epithelium • Function – secretion • Gland – a single cell or group of cells that secrete substances into ducts, onto a surface, or into the blood. • 2 types • Endocrine • Exocrine Dr. Michael P. Gillespie

45. Endocrine Glands • The secretions of endocrine glands enter the interstitial fluid and then diffuse directly into the bloodstream. • These secretions do NOT flow through a duct. • These secretions are called hormones. • Examples • Pituitary, thyroid, and adrenal glands Dr. Michael P. Gillespie

46. Exocrine Glands • Exocrine glands secrete their products into ducts that empty onto the surface of a covering and lining epithelium. • Types of secretions • Mucus, sweat, oil, earwax, sailva, digestive enzymes • Examples • Sudoriferous (sweat) and salivary glands Dr. Michael P. Gillespie

47. Dr. Michael P. Gillespie

48. Structural Classification of Glands • Unicellular – single celled • Multicellular – many celled – distinct organ • Simple - unbranched • Compound - branched • Tubular – tubular secretory parts • Acinar – rounded secretory portions • Tubular Acinar Dr. Michael P. Gillespie

49. Simple Glands • Simple tubular • Glands in Large Intestine • Simple branched tubular • Gastric glands • Simple coiled tubular • Sweat glands • Simple acinar • Glands of penile urethra • Simple branched acinar • Sebaceous glands Dr. Michael P. Gillespie

50. Compound Glands • Compound tubular • Bulbourethral (Cowper’s) glands • Compound acinar • Mammary glands • Compound tubuloacinar • Acinar glands of the pancreas Dr. Michael P. Gillespie