Tissues Histology: the study of tissues

Tissues  A group of interrelated cells that function together and perform specialized activities 4 Types of Tissues in the body Epithelial Epithelial Connective Connective Muscle Muscle Nervous Nervous

Epithelial Tissue  AKA: Epithelium (epi- upon or above) Functions: Functions: (P) Protection (S) Secretions (A) Absorption (F) Filtration

Epithelial Tissue  Characteristics Closely packed flat cells Closely packed flat cells Avascular (a- without vasc- blood supply), needs are met through diffusion from neighboring cells Avascular (a- without vasc- blood supply), needs are met through diffusion from neighboring cells

Epithelial Tissue  Location Coverings or linings of organs Coverings or linings of organs Always has a surface exposed to open space or the outside of the body (apical surface)Always has a surface exposed to open space or the outside of the body (apical surface) Underside always attached to connective tissue by a basement membraneUnderside always attached to connective tissue by a basement membrane Mitosis is frequent to replace damaged cells since they are “exposed” Mitosis is frequent to replace damaged cells since they are “exposed”

Types  Glandular Epithelium- Exocrine- secretes products into ducts Exocrine- secretes products into ducts This allows for the substance to be concentrated to one specific areaThis allows for the substance to be concentrated to one specific area Endocrine- secretes directly into blood Endocrine- secretes directly into blood nonspecificnonspecific endocrine exocrine

Types  Epithelial tissue is classified two ways By the cell shape By the cell shape By the number of cell layers By the number of cell layers Some may contain goblet cells….these cells are filled with and release mucus. (This type lines the digestive tract and are sometimes referred to as mucosae)

Epithelial Cell Shapes  Squamous- (squashed) flat, nucleus near surface  Cuboidal- (cube) thicker, square shaped with central nucleus

Epithelial Cell Shapes  Columnar- (column) elongated cells, some have microvilli (fingerlike projections that increase surface area), some have cilia (tiny hair-like structures that help move materials along)

Epithelial Cell Shapes  Transitional- appearance ranges from flat to columnar, cells can stretch and compress (different shapes in the same layer)

Arrangement of Layers  Simple- single layer, thinness allows substances to permeate easily  Stratified- (strat-layers) multiple layers, protection for areas that endure large amounts of stress, cells grow from the bottom layer up  Pseudostratified- (psuedo-false) one layer, but appears to be multilayered. All cells are attached to the basement membrane, but not all the cells reach the surface

Practice Looks  Epithelia Page Epithelia Page Epithelia Page  1. Simple Squamous 2. Simple Squamous 3. Simple Cuboidal 4. Simple Cuboidal 5. Simple Columnar 6. Simple Columnar 7. Pseudostratified Columnnar 8. Pseudostratified Columnnar (Ciliated) 9. Transitional 10. Transitional 11. Stratified Squamous 12. Stratified Squamous 13. Stratified Squamous 14. Stratified Squamous (Keratinized) 15. Stratified Squamous (Keratinized 16. Stratified (High) Cuboidal 17. Stratified Cuboidal 1. Simple Squamous 2. Simple Squamous 3. Simple Cuboidal 4. Simple Cuboidal 5. Simple Columnar 6. Simple Columnar 7. Pseudostratified Columnnar 8. Pseudostratified Columnnar (Ciliated) 9. Transitional 10. Transitional 11. Stratified Squamous 12. Stratified Squamous 13. Stratified Squamous 14. Stratified Squamous (Keratinized) 15. Stratified Squamous (Keratinized 16. Stratified (High) Cuboidal 17. Stratified Cuboidal 1. Simple Squamous 2. Simple Squamous 3. Simple Cuboidal 4. Simple Cuboidal 5. Simple Columnar 6. Simple Columnar 7. Pseudostratified Columnnar 8. Pseudostratified Columnnar (Ciliated) 9. Transitional 10. Transitional 11. Stratified Squamous 12. Stratified Squamous 13. Stratified Squamous 14. Stratified Squamous (Keratinized) 15. Stratified Squamous (Keratinized 16. Stratified (High) Cuboidal 17. Stratified Cuboidal

Epithelial Tissue  Extra Slides for at Home Review

Types of Epithelium  Simple Squamous- single, flat cell layer, nucleus in middle of the cell

Types of Epithelium  Simple Cuboidal- Single layer of cubed shaped cells, nucleus in the middle

Types continued  Simple Columnar- single layer of rectangular cells, nucleus at base, Non-ciliated- contains goblet cells (mucous) and microvilli (increase surface area) in some areas Non-ciliated- contains goblet cells (mucous) and microvilli (increase surface area) in some areas

 Simple Columnar- Ciliated- single layer of rectangular cells, nucleus at the base Ciliated- single layer of rectangular cells, nucleus at the base

Types- continued  Stratified Squamous- Several layers, larger at the bottom and flattened out at the top, bottom replaces top as the superficial layers shed, can produce keratin

Types- Continued  Stratified Cuboidal- two or more layers, cubed shaped cell

Types- Continued  Stratified Columnar- several layers on columnar in superficial layers

Types  Pseudostratified Columnar- single layer, nucleus at different levels, all cells attached to basement membrane

Types  Transitional- range from squamous to cuboidal appearance