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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 Connective Muscle Nervous. Epithelial Tissue. AKA: Epithelium (epi- upon or above) Functions:
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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 • Connective • Muscle • Nervous
Epithelial Tissue • AKA: Epithelium (epi- upon or above) • Functions: (P) Protection (S) Secretions (A) Absorption (F) Filtration
Epithelial Tissue • Characteristics • Closely packed flat cells • Avascular (a- withoutvasc- blood supply), needs are met through diffusion from neighboring cells
Epithelial Tissue • Location • Coverings or linings of organs • 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 membrane • Mitosis is frequent to replace damaged cells since they are “exposed”
Types endocrine • Glandular Epithelium- • Exocrine- secretes products into ducts • This allows for the substance to be concentrated to one specific area • Endocrine- secretes directly into blood • nonspecific exocrine
Types • Epithelial tissue is classified two ways • By the cell shape • 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)
Transitional- appearance ranges from flat to columnar, cells can stretch and compress (different shapes in the same layer) Epithelial Cell Shapes
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 • 1. Simple Squamous2. Simple Squamous3. Simple Cuboidal4. Simple Cuboidal5. Simple Columnar6. Simple Columnar7. Pseudostratified Columnnar8. Pseudostratified Columnnar (Ciliated)9. Transitional10. Transitional11. Stratified Squamous12. Stratified Squamous13. Stratified Squamous14. Stratified Squamous (Keratinized)15. Stratified Squamous (Keratinized16. Stratified (High) Cuboidal17. Stratified Cuboidal
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
Simple Columnar- • 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