Tissue level of organization

1. Tissue level of organization Fall 2012

2. vocab development • holos – entire • hyalos – glass • inter – between • krinein– to separate • lacus – lake • meros – part • neuro– nerve • os – bone • a – without • apo– front • cardium – heart • chondros– cartilage • dendron– tree • desmos – ligament • glia – glue • histos – tissue

3. Vocab development • peri – around • phagein– to eat • pleura – rib • pseudes – false • sistere – to set • soma – body • squama – plate or scale • vas – vessel

4. Four Tissue Types • cells combine to form tissues • tissues are groups of specialized cells and cell products that perform a limited number of functions • histology is the study of tissues • 4 basic types of tissues • epithelial • connective • muscle • neural

5. epithelial tissue • includes epithelia and glands • epithelia are layers of cells that cover internal or external surfaces • glands are composed of secreting cells derived from epithelia

6. Epithelial tissue • Important Characteristics • cells that are bound closely together • a surface exposed to the environment or to some internal chamber or passageway • attachment to underlying connective tissue by a basement membrane • absence of blood vessels • continual replacement or regeneration of epithelial cells that are damaged or lost at the exposed surface

7. Epithelial tissue • Functions of Epithelial Tissue • Provide physical protection • Control permeability • Provide sensation • Produce specialized secretions • Gland cells • Glandular epithelium • Exocrine- secretions are discharged to the surface of the epithelium • Endocrine- secretions are released into the surrounding tissue fluid and blood • These secretions are usually called hormones.

8. Intercellular connections • Undamaged epithelia form effective barriers. • The plasma membranes are held together by CAMs and by a thin layer of intercellular cement. • The CAMs bind to: • Cytoskeletal filaments • Each other • Extracellular materials • The CAMs form specialized attachment sites called cell junctions • 3 types of junctions • Tight junctions • Gap junctions • Desmosomes

9. Basement membrane • Lies between the epithelium and underlying connective tissues • No cells, it is made up of a network of proteins • Provides strength and resists distortion

10. Epithelial Renewal & Repair • Maintains its structures by the continuous division of stem cells • Stem cells are unspecialized cells • Found in the deepest layer of the epithelium, near the basement membrane

11. Classification of epithelia • Classified according to: • Number of cell layers • Shape of exposed cells

12. Classification of epithelia • Cell layers • Simple epithelium • Single layer of cells covering the basement membrane • Thin • Found in protected areas inside the body • Line internal compartments & passageways • Common where absorption & secretion takes place

13. Classification of epithelium • Cell layers • Stratified Epithelium • Several layers thick above the basement membrane • Found in areas subject to mechanical or chemical stresses

14. Classification of epithelium • Cell shapes • Squamous • Cells are thin & flat • Nucleus occupies the thickest portion of each cell • Cuboidal • Appear square in 2 dimensions • Appear hexagonal in 3 dimensions • Nucleus is near the center of each cell

15. Classification of Epithelium • Cell shapes • Columnar • Hexagonal, but taller & more slender than cuboidal • Nucleus is found near basement membrane

16. Classification of epithelia • Simple Squamous Epithelia • Found in protected regions where absorption takes place or a slippery surface • Ex: exchange surfaces of lungs, lining of ventral body cavities, lining of blood vessels • Simple Cuboidal Epithelia • Provides limited protection & occurs where absorption & secretion take place • Secret enzymes & buffers in the pancreas & salivary glands

17. Classification of epithelia • Simple Columnar Epithelia • Provide some protection & may occur in areas of absorption or secretion • Ex: lines the stomach, the intestinal tract, and many excretory ducts • Stratified Squamous Epithelia • Found where mechanical stresses are severe • Ex: surface of the skin, lining of the mouth, tongue, esophagus

18. Classification of epithelia • Stratified Cuboidal Epithelia • Relatively rare • Ex: along the ducts of sweat glands and the ducts of the mammary glands • Stratified Columnar Epithelia • Relatively rare • Ex: portions of the pharynx, epiglottis, urethra

19. Classification of epithelia • Psuedostratified Epithelia • Called this because it looks stratified but it is not • Found in portions of the respiratory tract • Transitional Epithelia • Stratified epithelium that tolerates repeated stretching • Lines the urinary bladder

20. Glandular Epithelia • Exocrine secretions are produced by exocrine glands and are discharged through a duct to the outside. • Endocrine secretions are produced by ductless glands and are released into blood or tissue fluids

21. Glandular Epithelia • Mechanisms of Secretion • Merocrine secretion • Most common form of secretion • Leaves the cell intact and able to function • Product is released from secretory vesicles by exocytosis • Ex: mucus

22. Glandular epithelia • Mechanisms of Secretion • Apocrine secretion • Involves the loss of cytoplasm and the secretory product • Leaves the cell intact and able to function

23. Glandular Epithelia • Mechanisms of Secretion • Holocrine secretions • Entire cell becomes packed with secretions and bursts and dies • Ex: sebaceous glands

24. Glandular epithelia • Types of secretions • Serous • Watery solution contains enzymes (saliva) • Mucous • Thick, slippery mucus (snot) • Mixed • Contains more than one type of secretion

25. Connective tissues • 3 basic components • Specialized cells • Protein fibers • Ground substance • Fluid • Matrix- extracellular protein fibers & ground substance that surround the cells of connective tissue

26. Connective tissues • Never exposed to the outside • Highly vascularized • Contain receptors that provide pain, pressure, temperature, & other sensations

27. Connective Tissues • Functions • Support & Protection • Transportation of materials • Storage of energy reserves • Defense of the body

28. Connective tissues • Three major types • Connective tissue proper • Fluid connective tissues • Blood • lymph • Supporting connective tissues • Cartilage • Bone

29. Connective Tissue proper • Cells found in connective tissue proper • Fibroblasts • Fibrocytes • Macrophages • Fat cells (adipocytes) • Mast cells

30. Connective tissue Proper • 3 types of connective tissue fibers • Collagen fibers • Most common fibers in connective tissue proper • Elastic fibers • Return to their original shape after stretching • Reticular fibers • Least common • Form the framework of various organs

31. Connective Tissue Proper • Types of connective tissue proper • Classified into types based on their relative proportions or cells, fibers, & ground substance • Loose • Dense

32. Connective tissue Proper • Loose Connective Tissues • Locations • Beneath the dermis of the skin • Digestive tract • Respiratory and urinary tracts • Between muscles • Around blood vessels, nerves, & joints

33. Connective Tissue Proper • Loose connective tissue functions. • Cushions organs • Provides support, but allows independent movement • Phagocytic cells defend against pathogens

34. Connective tissue proper • Loose Connective Tissue • Adipose tissue (composed mainly of triglycerides) • Locations: • Underneath the deep skin (sides, buttocks, breasts) • Padding around eyes and kidneys • Functions: • Provides padding & cushions shocks • Insulates • Stores energy reserves

35. Connective Tissue Proper • Dense Connective Tissue • Locations: • Between skeletal muscles & skeleton • Tendons- connect muscle to bone • Between bones • Ligaments – connect bone to bone • Covering skeletal muscles • Capsules of internal organs

36. connective tissue proper • Dense connective tissue • Functions: • Provides firm attachment • Conducts pull of muscles • Reduces friction between muscles • Stabilizes relative position of bones • Helps prevent over expansion of organs (bladder)

37. Fluid connective tissues • 2 types • Blood • Plasma- watery matrix • Red blood cells • Account for half the volume of blood • Transport oxygen through the blood • White blood cells- immune response • Platelets- clotting • Lymph • Forms as interstitial fluid enter lymphatic vessels • Circulated throughout the entire body • Supports your immune system

38. Supporting connective tissues • 2 types • Cartilage • Bone

39. Supporting connective tissues • Cartilage • Heals poorly because it is avascular • 3 types of cartilage • Hyaline cartilage • Elastic cartilage • Fibrous cartilage

40. Supporting connective tissues • Elastic Cartilage • Locations: • Auricle of external ear • Epiglottis • Auditory tube • Part of larynx • Functions: • Provides support • tolerates distortion without damage and returns to original shape

41. Supporting connective tissues • Hyaline Cartilage • Locations: • Between tips of ribs & bones of the sternum • Cover bone surfaces at synovial joints • Supporting larynx, trachea, & bronchii • Forms part of the nasal septum • Functions: • Provides stiff but somewhat flexible support • Reduces friction between bony surfaces

42. Supporting connective tissues • Fibrous Cartilage • Locations: • Pads within knee joint • Between the pubic bones of the pelvis & intervertebral discs • Functions: • Resists compression • Prevents bone on bone contact • Limits relative movement

43. Supporting connective tissues • Bone • Osteocytes- cells that make up bones (hard outer part of the bone) • Periosteum- covering around the bone

44. MEMBRANES • Membranes are physical barriers • 4 types • Mucous • Serous • Cutaneous • Synovial

45. Membranes • Mucous Membranes • Line cavities • Communicate with the exterior

46. Membranes • Serous Membranes • Line sealed, internal sub divisions of the ventral cavity • 3 serous membranes • Pleura- line the pleural cavities and covers the lungs • Peritoneum- line the abdominal cavity & covers the surface of the enclosed organs • Pericardium- lines the pericardial cavity & covers the heart • Parietal & visceral portions • Parietal portion- lines the inner surface of the cavity • Visceral portion- covers the outer surface of organs within the body cavity • Primary function: Minimize friction between the parietal and visceral surfaces when an organ moves or changes shape

47. Membranes • Cutaneous Membrane • Covers the surface of the body (skin) • Thick • Waterproof • Usually dry • Consists of: stratified squamous epithelium & underlying dense connective tissues

48. Membranes • Synovial Membranes • Consist primarily of loose connective tissue & an incomplete layer of epithelial tissue • Found in joints that are allowed to move free • Lubricates joints

49. Muscle Tissue • Specialized from contraction • 3 types: • Skeletal • Cardiac • Smooth

50. Muscle Tissue • Skeletal Muscle Tissue • Cells- long, cylindrical, striated, multinucleate • Locations: • Combined with connective tissues & neural tissue in skeletal muscles • Functions: • Moves or stabilized the position of the skeleton • Guards entrances and exits to the digestive, respiratory, and urinary tracts • Generates heat • Protects internal organs