Tissue

1. Tissue The Living Fabric

2. Section 1 Pages 118-124

3. Epithelial Tissue • Epithelial tissue (epithelium) • Sheet of cells that covers a body surface or lines a body cavity. • Two types: • Covering and lining epithelium • Outer layer of skin, lines open cavities • Glandular epithelium • Fashions the glands of the body

4. Epithelial Tissue • Epithelium has many functions: • Protections • Absorption • Filtration • Excretion • Secretion • Sensory reception

5. Classification of Epithelia • Each epithelium is given two names • First - # of layers • Simple and stratified • Simple epithelia – single cell layer (found where absorbtion and filtration occur • Stratified epithelia – two or more layers (high abrasion areas)

6. Classification of Epithelia • Second name – shape of cells • Three common shapes • Squamous cells – flattened and scalelike • Cuboidal cells – boxlike • Columnar cells - tall and column shaped

8. Simple Epithelia • Simple Squamous • Flattened laterally, cytoplasm is sparse • Look like a fried egg • Allows passage of materials by diffusion and filtration • Areas where protection is not important • Kidneys, air sacs of lungs, lining of heart • Two names that reflect their location • Endothelium – ‘inner covering’ • Mesothelium – covering organs

9. Simple Cuboidal Epithelium • Consists of a single layer of cells as tall as they are wide, spherical central nuclei • Functions: • Secretion • Absorption • Location • Ovary surface, ducts and secretory protions of small glands

10. Simple Columnar Epithelium • Single layer of tall closely packed cells, round/oval nuclei • Some contain cilia which help move substances through pathway • Function: • Absorption, secretion of mucus • Location: • Lines most of the digestive tract, gallbladder

11. Stratified Epithelia • Two or more layers of cells • More durable • Regenerate from below • Role is protection

12. Stratified Epithelia • Stratified Squamous Epithelium • Thick membrane composed of several layers • Function: • Protects underlying tissues in areas subjected to abrasion • Locations: • Moist linings of mouth and esophagus

13. Stratified Epithelia • Stratified Cuboidal and Columnar Epithelia • Cuboildal • Quite rare in the body • Mostly found in ducts of larger glands • Columnar • Small amounts are found in pharynx, and lining of some glandular ducts

15. Connective Tissue

16. Connective Tissue • Found everywhere in the body • Most abundent and widely distributed of the primary tissues • Four main classes • Connective tissue proper • Catilage • Bone tissue • blood

17. Connective Tissue • Functions: • Binding and support • Protection • Insulation • Transportation of substances within the body

18. Common Characteristics • Despite their diverse functions, they have many common characteristics • Common origin • All connective tissue comes from mesenchyme (embryotic tissue) • Degrees of vascularity • Have many degrees of vascularity (contain vessels) • Extracellular Matrix • Seperates the living cells of the tissue • Because of matrix connective tissue can bear weight

19. Structural Elements of Connective Tissue • Connective Tissues have 3 main elements: • Ground substance • Fibers • Cells

20. Ground Substance • Unstructured material that fills the space between the cells and contains the fibers • Composed of: • Interstitial fluid • Cell adhesion proteins • Acts like glue, helps attach themselves to matrix elements • Proteoglycans • Holds large amounts of fluid and functions as a molecular sieve, or medium for nutrients to diffuse between blood capliaries and cells

21. Fibers • Provide support • Three main types of fibers: • Collagen • Elastic • Reticular fibers

22. Fibers • Collagen fibers • By far the strongest and most abundant • Constructed mainly of collagen • Secreted into the extracellular space • Cross-linked fibrils • Because of this cross-linked pattern they are very strong • Have a glistening white appearance – also called white fibers

23. Elastic Fibers • Long, thin fibers that form branching networks in the extracellular matrix • Contain rubber-like protein elastin • Allows them to stretch and recoil • Found where elasticity is needed • Skin, lungs, and blood vessel walls • Sometimes called yellow fibers

24. Reticular Fibers • Short, fine, collagenous fibers • Branch extensively, forming delicate networks that surround small blood vessels and support soft tissue

25. Cells • Each connective tissue has a fundamental cell type • Blast – ‘bud’ or ‘sprout’, means ‘forming’ • Primary blast cell types by connective tissue class are: • Connective tissue proper (fibroblast) • Cartilage (Chondroblast) • Bone (osteoblast) • Blood (hematopoietic stem cell) • Is no located in its tissue (blood) • These cells make the matrix of their connective tissue.

26. Connective Tissue Proper • Has two subclasses: • Loose connective tissues • Dense connective tissues • Except for bone and blood, all mature connective tissues belong to this class

27. Loose Connective Tissue • Areolar Connective Tissue • Gel-like matrix with three fiber types • Fibroblasts, macrophages, mast cells, and some white blood cells • Function • Wraps and cushions organs • Plays important role in inflammation (holds fluids) • Location • Widely distributed under epithelia of body • Surrounds capillaries

28. Loose Connective Tissue • Adipose (fat) tissue • Closely packed fat cells • Have nucleus pushed to side by large fat droplet • Function: • Provides reserve food fuel • Insulates against heat loss • Supports and protects glands • Location: • Under skin • Around kidneys and eyeballs • Within abdomen and breasts

29. Loose Connective Tissue • Reticular Connective Tissue • Network of reticular fibers in a typical loose ground substance; lie on the network • Function: • Fibers from soft internal skeleton that supports other cell types of cells including white blood cells • Location: • Lymphoid organs

30. Pictures Areolar Tissue Adipose Tissue Reticular Tissue