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Anatomy Test 2
Chapter 4
| Term | Definition |
|---|---|
| Tissues | Groups of cells similar in structure that perform common or related function |
| Histology | – Study of tissues |
| 4 Main Tissues | • Epithelial tissue – Covers • Connective tissue – Supports • Muscle tissue – Produces movement • Nerve tissue – Controls |
| Studying Human Tissue: Microscopy | • Tissue is fixed – Preserved • Cut – Sliced thin enough to transmit light or l t electrons • Stained – Enhances contrast |
| Epithelial Tissue (Epithelium) | • Form boundaries • Two main types (by location) – Covering and lining epithelia • On external and internal surfaces Gl d l ith li – Glandular epithelia • Secretory tissue in glands |
| Epithelial Tissue Functions | • Protection • Absorption • Filtration • Excretion • Secretion • Sensory reception |
| Five Characteristics of Epithelial Tissues | • Polarity • Specialized contacts • Supported by connective tissues • Avascular, but innervated • Can regenerate |
| Characteristics of Epithelial Tissue: Polarity | • Cells have polarity – Apical surface (upper free) exposed to exterior or cavity – Basal surface (lower, attached) Both surfaces differ in structure and function |
| – Apical Surface of Epithelial Tissues | • May be smooth & slick • Most have microvilli (e.g., brush border of intestinal lining) – Increase surface area • Some have cilia (e.g., lining of trachea) |
| Basal Surface of Epithelial Tissues | • Noncellular basal lamina – Glycoprotein and collagen fibers lies adjacent to basal surface – Adhesive sheet Selective filter – Scaffolding for cell migration in wound repair |
| Characteristics of Epithelial Tissue: Specialized Contacts | • Covering and lining epithelial tissues fit closely together – Form continuous sheets • Specialized contacts bind adjacent cells © 2013 Pearson Education, Inc. – Lateral contacts • Tight junctions • Desmosomes |
| Characteristics of Epithelial Tissue: Connective Tissue Support | • All are supported by connective tissue • Reticular lamina Deep to basal lamina Network of collagen fibers • Basement membrane B L + R L Reinforces epithelial sheet Resists stretching and tearing Defines epithelial boundary |
| Characteristics of Epithelial Tissue: Avascular but Innervated | • No blood vessels in epithelial tissue – Must be nourished by diffusion from underlying connective tissues • Is supplied by nerve fibers |
| Characteristics of Epithelial Tissue: Regeneration | • High regenerative capacity • Stimulated by loss of apical-basal polarity and lateral contacts – Some exposed to friction – Some exposed to hostile substances • If adequate nutrients can replace lost cells by cell division |
| Classification of Epithelia | • All epithelial tissues have two names –# of layers • Simple epithelia = 1 layer • Stratified epithelia = 2 or more layers – Shape • Squamous • Cuboidal • Columnar • In stratified epithelia, epithelia classified by cell shape in apical layer |
| Cells of Epithelial Tissues | • Squamous cells – Flattened and scalelike – Nucleus flattened • Cuboidal cells © 2013 Pearson Education, Inc. – Boxlike – Nucleus round • Columnar cells – Tall; column shaped – Nucleus elongated |
| Classification of Epithelia: Simple Epithelia | • Absorption • Secretion • Filtration • Very thin |
| Simple Squamous Epithelium | • Cells flattened laterally • Cytoplasm sparse • Function where rapid diffusion is priority – i.e., kidney, lungs • Note description, function, location on next slide |
| Simple Squamous Epithelium | • Two other locations – Endothelium • The lining of lymphatic vessels, blood vessels, and heart – Mesothelium • The epithelium of serous membranes in the ventral body cavity |
| Simple Cuboidal Epithelia | • Single layer of cells • Secretion • Absorption • Forms walls of smallest ducts of glands and many kidney tubules • Note description, function, location on next slide |
| Simple Columnar Epithelium | • Single layer of tall, closely packed cells • Absorption • Secretion • Note description, function, location on next slide |
| Pseudostratified Columnar Epitheliem | • Cells vary in height – Cell nuclei at different levels – Appears stratified, but is not – Secretion Ab ti – Absorption – Note description, function, location on next slide |
| Stratified Epithelial Tissues | • Two or more cell layers • Regenerate from below – Basal cells divide, cells migrate to surface • More durable than simple epithelia • Protection is major role |
| Stratified Squamous Epithelium | • Most widespread of stratified epithelia • Free surface squamous; deeper layers cuboidal or columnar • Located for wear and tear • Those farthest from basal layer (and therefore nutrients) less viable |
| Stratified Columnar Epithelium | • Limited distribution in body • Small amounts in pharynx, male urethra, and lining some glandular ducts • Also occurs at transition areas between two other types of epithelia • Only apical layer columnar |
Created by:
sarahflagg
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