TISSUES

1. TISSUES HONORS ANATOMY & PHYSIOLOGY

2. Tissues & Homeostasis • 4 basic types of tissues in human body contribute to homeostasis by providing diverse functions including • protection • support • communication among cells • resistance to disease • & many more

3. Definition • a tissue is a group of similar cells that usually have a common embryonic origin & function together to carry out specialized activities

4. Tissues • their structure & properties are influenced by factors such as: • nature of the extracellular material surrounding tissue cells • type of connections between cells

5. Classification of Tissues • Epithelial • covers body surfaces & lines hollow organs, cavities, & ducts • forms glands • Connective • protects & supports • Muscular • movement • Nervous • detects changes in/out body & responds by generating action potentials

6. Embryology of Tissues • Epithelial • from all 3 layers • Connective • mesoderm • Muscular • mesoderm • Nervous • ectoderm

7. Cell Junctions • are contact pts between plasma membranes of adjacent cells • found between most epithelial cells & some muscle & nerve cells

8. Surfaces of Cells

9. Basement Membrane (bm) • thin, extracellular layer • commonly has 2 parts: • basal lamina • reticular lamina

10. Covering & Lining Epithelium • classified according to 2 characteristics: • # of layers • single layer = simple • multiple layers = stratified • single layer that looks like multiple = psuedostratified 2. cell shape • squamous • cuboidal • columnar

11. Simple Epithelium • 1 layer of cells, often in sheets • functions: • diffusion/osmosis • filtration • secretion: production & release of substances (sweat, mucus) • absorption: intake of fluids or other substances

12. Pseudostratified Epithelium • appears to have multiple layers because: • nuclei @ different layers • not all cells reach apical surface

13. Stratified Epithelium • 2 or more layers of cells • named by shape of top layer • function: protection where there is considerable wear & tear

14. Squamous Cells • arranged like floor tiles • very thin: allows for rapid passage of substance thru cell

15. Cuboidal Cell • shaped like cubes or hexagons • +/- microvilli on apical surface • finger-like cytoplasmic projections • function increase surface area • function: secretion or absorption

16. Columnar Cells • taller than they are wide • +/- microvilli or cilia on apical surface • cilia: tiny hair-like projections that beat in unison: moves substances across surface of cell • function: • protection • absorption • secretion

17. Simple Squamous Epithelium • single layer flat cells • viewed from • apical surface looks like tiled flooring • cross-section: fried eggs cross section

18. Simple Squamous Epithelium • found: • @ sites where filtration (kidneys) or diffusion (lungs, capillaries) occur • lines blood vessels & chambers in heart (endothelium), forms lining for serous membranes (mesothelium)

19. Simple Cuboidal Epithelium • nuclei round & centrally located • functions: • secretion • absorption • found in: • thyroid gland • kidneys

20. Simple Columnar Epithelium • 2 forms: nonciliated/ciliated • nonciliated simple Columnar Epithelium • 2 types: • Columnar epith. w/microvilli on apical surfaces • Goblet cells • produce & secrete mucus

21. Ciliated Simple Columnar Epithelium • cilia on apical surface • +/- Goblet cells • functions: • move mucus or any foreign objects away from lower respiratory tract or ova towards uterus • found in: • airways of upper respiratory system • fallopian (uterine) tubes

22. Pseudostratified Columnar Epithelium • all cells attached to bm but not all reach apical surface • Ciliated Pseudostratified Columnar Epith.: • cells that do reach apical surface either are goblet cells or are ciliated • NonciliatedPseudostratified Columnar Epith: • no cilia or goblet cells

23. StratifedSquamous Epithelium • basal layer continually undergoing cell division • as new cells grow, cells near base pushed upward • as near apical border moving farther away from their blood supply (in underlying connective tissue)  dehydrate, shrink, harden, die  cell jcts break down  cells sloughed off

24. Stratified Squamous Epithelium Keratinized Nonkeratinized upper layers contain keratin: tough, fibrous protein that protects underlying tissues from heat, microbes, chemicals found: skin found: lining mouth (buccal mucosa) & esophagus protect underlying tissues from wear & tear and from invasion by microbes

25. Glandular Epithelium • gland: single cell or group of cells that secrete substances into: • ducts • onto a surface • into blood • classified: • endocrine • secretions  intercellular fluid  capillary • exocrine • secretions  ducts  surface of skin or lining of hollow organ

26. Classification of Glands

27. Connective Tissue (CT) • most abundant & widely distributed tissue in body • 2 basic elements: • extracellular matrix • cells

28. Extracellular Matrix • greater % in CT than other tissues • it’s the material located between cells (secreted by those cells) • determines qualities of the CT • not usually found on surfaces, usually rich blood supply (x cartilage & tendons) • consists of: • protein fibers • ground substance

29. CT Cells • immature form suffix “blast” • large capacity to divide • secrete matrix • mature form suffix “cyte” • less likely to divide • maintain matrix

30. Fibroblasts • large flat cells w/ branching processes • found in most CT • migrate thru CT secreting fibers & ground substance

31. Macrophages • develop from monocytes • phagocytes • irregular shape • 2 types: • wandering • move to sites of infection or inflammation • fixed • reside in a particular tissue • ex: alveolar macrophages

32. Plasma Cells • small cells that develop from B lymphocytes • Important in immune response • most reside in CT • GI & respiratory tracts • lymph nodes, spleen, red bone marrow

33. Mast Cells • found along side blood vessels that supply CT • produce & secrete histamine: dilates small blood vessels as part of inflammatory response (reaction to injury or infection) • can also bind, ingest, & kill bacteria

34. Adipocytes • aka adipose cells or fat cells • store triglycerides • functions: • store fats for nrg • insulate • cushion organs

35. Ground Substances • acellular component of CT that supports cells, binds them together, stores water, provides medium thru which substances are exchanged between blood & cells • may be: • fluid • semifluid • gelatinous • calcified

36. CT Fibers: 3 Types • Collagen • “colla” = glue a protein (25% of all protein in body!) • very strong fibers that resist pulling • Elastic • smaller strong but stretchy fibers • made of protein called elastin • plentiful in skin, blood vessel walls, lung tissue • Reticular • made of collagen in fine tubes coated with glycoproteins forming branching networks & found in BM • skin, adipose, reticular CT (spleen, lymph nodes)

37. Mature CT: Loose CT • Areolar CT • 1 of most abundant types • includes all types of CT cells & fibers • found in: subcutaneous tissue

38. Mature CT: Loose CT 2. Adipose Tissue • cells: adipocytes • found ass’c with areolar CT • 2 types: • white • most of the adipose in adults • brown • darker due to rich blood supply • widespread in newborns: helps maintain body temperature

39. Mature CT: Dense CT • contains more numerous fibers but fewer cells than in loose CT • 3 types: • Dense Regular CT • Dense Irregular CT • Elastic CT

40. Dense Regular CT • collagen fibers lined up in parallel pattern allowing it to withstand pulling alingaxxis of fibers: very strong tissue • silvery white, tough • ex: tendons & most ligaments

41. Dense Irregular CT • collagen fibers irregularly arranged • found where pulling forces exerted in various directions • found: dermis, pericardium, periosteum

42. Elastic CT • predominate fiber: elastic fibers • quite strong & able to return to original shape after being stretched • found: elastic arteries, lungs

43. Membranes • are flat sheets of pliable tissue that cover or line a part of the body • 2 types: • epithelial membrane: • epithelial layer + underlying CT • types: mucous membrane, serous membrane, cutaneous membrane (skin) • synovial membrane: • + CT but - epithelium • line joints

44. Mucous Membranes (Mucosa) • line body cavities that open directly to exterior • line: entire digestive, upper respiratory, & reproductive tracts • cells connected by tight jcts • Goblet cells secrete • mucus  slippery so prevents cavities from drying out • enzymes from some • site of nutrient absorption

45. Serous Membranes (Serosa) • line cavities that do not open directly to exterior & covers organs w/in those cavities • made of: areolar CT covered by mesothelium (simple sq. epith.) which secretes serous fluid • 2 layers: • parietal peritoneum • covers cavity wall • visceral peritoneum • covers organs • in pericardial cavity = pericardium • in abd. Cavity = peritoneum

47. CARTILAGE • consists of a dense network of collagen (strength) & elastic (flexibility) fibers, no blood vessels or nerves (x perichondrium) so heals very slowly • chondrocytes: mature cartilage cells • occur singly or in small groups w/in space called lacunae • perichondrium: membrane of dense CT • covers surface of most cartilage

48. Cartilage • 3 types: • Hyaline cartilage • most abundant cartilage in body, also the weakest • provides flexibility & support • Fibrocartilage • no perichondrium • provides strength & rigidity (strongest of the 3) • Elastic cartilage • + elastic fibers • provides strength & elasticity

49. Bone Tissue • aka osseous tissue • 2 types: • Compact bone • Spongy bone

50. Compact Bone • basic unit of compact bone is the osteon (haversian system) • has 4 parts: • Lamellae • concentric rings of extracellular material & collagen • make bone hard & strong • Lacunae • Canaliculi • Central (haversian) canal)