Chapter 4 Tissue Level Flashcards
Epithelial tissue
Covers body surfaces and lines hollow organs, cavities, and ducts. Also forms glands.
Allows body to interact with internal and external environment
Is avascular.
Connective tissue
Protects and supports the body and its organs. Binds organs together, stores energy reserves, provides immunity
Muscular tissue
Composed of cells specialized for contraction and generation of force. Generates heat.
Nervous tissue
Detects changes inside and outside the body. Activates muscular contractions and glandular secretions.
Tight junctions
Transmembrane proteins that fuse the outer surfaces of adjacent plasma membranes. Seals off pathways between adjacent cells.
Inhibits passage between cells, prevent organ contents from leaking
Adhering junctions
Contain plaque. Attached to membrane proteins and microfilaments. Cadherins join the cells. Forms zones called adhesion belts.
Resists separations during contraction
Desmosomes
Contain plaque and cadherins. Attaches to intermediate filament. Prevent separation during contraction. Common among epidermis.
Hemidesmosomes
Do not link adjacent cells. Contains transmembrane glycoproteins called integrins.
Anchors cells to a basement membrane.
Gap junctions
Contains proteins called connexins. Form tunnels called connexons which allows passage of small molecules between different cells.
Common in nervous system, GI tract, uterus, heart.
Epithelial tissue cellular arrangements
Cells in continuous sheets in either single or multiple layers.
2 general types:
Surface epithelium
Glandular epithelium
Surface epithelium
Forms outer covering of skin and some internal organs. Forms inner lining of blood vessels, ducts, body cavities, respiratory, digestive, urinary, genital systems.
Glandular epithelium
Makes up secreting portion of glands, such as thyroid, adrenal, sweat, and digestive glands.
Apical surface
Faces the body surface, body cavity, lumen, or tubular duct that receives cell secretions.
Epithelial lateral surface
Faces adjacent cells on either side. May contain tight junction, adhering junction, desmosomes, or gap junctions.
Epithelial basal surface
Surfaces the deepest layer of epithelial cells. Adheres to extracellular materials such as basement membrane.
Basement membrane
Commonly consists of the basal lamina and the reticular lamina. Forms a surface for epithelial cells to migrate, restricts passage of larger molecules, participates in filtration.
Basal lamina
Closer to and secreted by epithelial cells. Adheres to integrins in hemidesmosomes and attaches epithelial cells to basement membrane.
Reticular lamina
Closer to underlying connective tissue. Contains collagen.
2 types of surface epithelial tissues
Simple epithelium
Stratified epithelium.
Simple epithelium
Single layer of cells functioning in secretion or absorption.
Simple squamous, cuboidal, columnar, psuedostratified.
Pseudostratified epithelium
Appears to have multiple layers of cells. Not all cells reach the apical surface. All cells rest on the basement membrane. May contain cilia or secrete mucus.
Stratified epithelium
2 or more layers of cells that protect underlying tissues.
Stratified squamous, cuboidal, columnar.
Epithelial cell shapes
Squamous
Cuboidal
Columnar
Transitional
Squamous epithelial cells
Thin cells which allow rapid passage of substances through them.
Cuboidal epithelial cells
Shaped like cubes or hexagons. May have microvilli. Function in secretion or absorption
Columnar epithelial cells
Taller than they are wide. Protect underlying tissues. May have cilia or microvilli. Specialized for secretion and absorption
Transitional epithelial cells
Change shape from squamous to cuboidal and back as organs distend and collapse.
Glandular epithelium
Secretes substances into ducts, onto a surface, or eventually into the blood.
Endocrine glands
Secrete hormones into interstitial fluid which diffuses into the blood without flowing through a duct.
Exocrine glands
Secrete products into ducts that empty onto an epithelium that covers or lines a surface.
Classified as unicellular or multicellular.