1. HISTOLOGY The study of tissues

2. Levels of organization in the biosphere

3. What is a tissue? Groups of cells with a common structure and function –Structure is suited to its function

4. General types of tissues Epithelial tissue Connective tissue Nervous tissue Muscle tissue

5. Epithelial tissue Covers outside of body and lines organs and cavities inside the body –Functions as a protective barrier Protects against injury Protects against invasion by bacteria, etc.

6. Epithelial Tissue Classified by number of cell layers and shape of cells Remember: form reflects function!

7. Epithelial Tissue By Layers: –Simple epithelium Single layer of cells –Stratified epithelium Multiple layers of cells –Pseudostratified epithelium Single layer of cells that appears to be multi- layered

8. Epithelial Tissue By shape: –Cuboidal –Columnar –squamous

9. Epithelial Tissue

10. Epithelial Tissue: Examples Simple cuboidal epithelium

11. Epithelial Tissue: Examples Simple columnar epithelium

12. Epithelial Tissue: Examples Simple squamous epithelium

13. Epithelial Tissue: Examples Stratified squamous epithelium

14. Epithelial Tissue: Examples Stratified squamous epithelium with layer of keratin

15. Epithelial Tissue: Examples Pseudostratified columnar epithelium

16. Connective Tissue Functions to bind and support other tissues –Few cells scattered in a matrix of various substances

17. Connective tissue fibers Collagenous Elastic reticular

18. Collagenous fibers Made of collagen Non-elastic

19. Elastic fibers Long threads made of elastin Rubbery

20. Reticular fibers Thin Branched Composed of collagen Form tightly woven fabric

21. Main types of connective tissue Loose connective tissue Adipose tissue Fibrous connective tissue Cartilage Bone blood

22. Loose connective tissue Most common Has all 3 fiber types (collagenous, elastic, reticular) Binds epithelia to underlying tissues, holds organs in place Fibroblasts and macrophages scattered in the mesh Also called “areolar” connective tissue

23. Loose connective tissue

24. Adipose tissue Specialized form of loose connective tissue Stores fat Act as insulation and fuel

25. Adipose tissue

26. Fibrous connective tissue Large numbers of collagen fibers –Arranged in parallel bundles –Strong –Found in tendons (join muscle to bone) and ligaments (join bone to bone)

27. Fibrous connective tissue

28. Cartilage Collagen fibers embedded in a rubbery matrix of chondroitin sulfate –Strong, yet flexible –In human ears, nose, rings of trachea Flexible support –Chondrocytes secrete chondroitin and collagen

29. Cartilage

30. Bone Mineralized connective tissue--hard Osteoblasts = bone-forming cells May be compact or spongy (cancellous) Repeating units are called osteons (Haversian systems)

31. Bone

32. Blood Matrix = plasma –Made of salt, water, dissolved proteins Types of cells: –Erythrocytes = RBC’s –Leukocytes = WBC’s –platelets

33. General types of tissues Epithelial Connective Nervous Muscle

34. Nervous Tissue Functional unit = neuron –Transmit nerve impulses Structure: –Cell body, dendrites, axons Dendrites transmit impulses from tips toward the neuron cell body Axons transmit impulses toward another neuron or a muscle cell

35. Neuron

36. Muscle Tissue Fibers are capable of contraction Made of proteins, actin and myosin 3 types –Skeletal –Cardiac –smooth

37. Skeletal Muscle tissue Attached to bones by tendons Responsible for voluntary movement Striated appearance

38. Cardiac Muscle In heart Striated, but cells are branched

39. Smooth Muscle Lacks striations Spindle-shaped Responsible for involuntary movements Lines digestive tract, bladder, arteries

40. Types of Muscle tissue