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Vocabulary flashcards covering key terms and definitions from the lecture on epithelial tissue, including embryonic origins, structural features, junctions, surface specializations, epithelial classifications, and glandular concepts.
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Tissue
A group of structurally and functionally related cells sharing a common embryonic origin.
Epithelial Tissue
One of the four basic tissue types; forms coverings, linings, and glands.
Surface Epithelium
Epithelial layer that lines or covers external and internal body surfaces.
Glandular Epithelium
Epithelial cells specialized for secretion; forms exocrine and endocrine glands.
Connective Tissue
Basic tissue type that supports, binds, and protects organs; includes CT proper, bone, cartilage, blood.
Muscle Tissue
Basic tissue type specialized for contraction; skeletal, cardiac, and smooth forms.
Nervous Tissue
Basic tissue type specialized for rapid communication via electrical impulses.
Zygote
Fertilized egg cell; common origin of all body tissues.
Blastocyst
Early embryonic stage that develops from zygote before gastrulation.
Gastrula
Embryonic stage where three germ layers (ectoderm, mesoderm, endoderm) form.
Ectoderm
Outer germ layer; gives rise to epidermis, neurons, pigment cells.
Mesoderm
Middle germ layer; forms muscle, kidney tubules, red blood cells, etc.
Endoderm
Inner germ layer; forms alveolar cells, thyroid, pancreatic cells.
Basement Membrane
Extracellular layer beneath epithelium composed of basal lamina and reticular lamina.
Basal Lamina
Thin sheet of glycoproteins and collagen directly under epithelial cells.
Lamina Fibroreticularis (Reticular Lamina)
Collagen-rich layer attaching basal lamina to underlying connective tissue.
Apical Pole
Surface of an epithelial cell facing the lumen or free space.
Basal Pole
Surface of an epithelial cell in contact with the basement membrane.
Tight Junction (Zonula Occludens)
Most apical cell junction forming a water-tight seal between adjacent cells.
Adherens Junction (Zonula Adherens)
Belt-like junction linking actin filaments of neighboring cells.
Desmosome (Macula Adherens)
Spot junction providing strong adhesion via intermediate filaments.
Gap Junction (Nexus)
Communicating junction allowing passage of ions and small molecules between cells.
Hemidesmosome
Structure anchoring epithelial basal pole to the basal lamina.
Interdigitation
Finger-like lateral membrane infoldings that increase adhesion surface.
Microvilli
1 µm finger-like plasma-membrane extensions that increase apical surface area for absorption.
Cilia (Kinocilia)
7–10 µm motile apical projections specialized for moving mucus or fluid.
Stereocilia
Long, non-motile microvilli; increase surface area, found in epididymis and inner ear.
Flagella
~50 µm long whip-like projection propelling a cell, e.g., spermatozoon.
Basal Infoldings
Deep invaginations of basal plasma membrane enhancing ion transport and absorption.
Simple Epithelium
Single cell layer with all cells touching the basement membrane.
Stratified Epithelium
Two or more cell layers; only basal layer contacts basement membrane.
Simple Squamous Epithelium
Single layer of flat cells; lines alveoli, serous cavities (mesothelium), blood vessels (endothelium).
Simple Cuboidal Epithelium
Single layer of cube-shaped cells; forms kidney tubules, gland ducts, ovary surface.
Simple Columnar Epithelium
Single layer of tall cells; lines digestive tract, gallbladder; ciliated form in bronchi, uterine tubes.
Pseudostratified Epithelium
Single layer of varying-height cells that appear stratified; ciliated in trachea (respiratory epithelium).
Stratified Squamous Epithelium
Many layers; apical cells flat. Keratinized in skin, non-keratinized in mouth, esophagus, vagina.
Stratified Cuboidal Epithelium
2–3 layers of cuboidal cells; lines ducts of sweat, mammary, salivary glands.
Stratified Columnar Epithelium
Rare epithelium with columnar superficial cells; found in conjunctiva, large ducts.
Transitional Epithelium
Stratified epithelium with dome-shaped surface cells; stretches in ureter and bladder.
Gland
Organized epithelial tissue specialized for secretion.
Exocrine Gland
Gland that releases secretions onto an epithelial surface via ducts.
Endocrine Gland
Ductless gland that releases hormones into the bloodstream.
Unicellular Gland
Single secretory cell within epithelium; e.g., goblet cell.
Goblet Cell
Cup-shaped unicellular gland secreting mucin in respiratory and intestinal tracts.
Multicellular Gland
Gland composed of duct plus secretory units.
Simple Gland
Exocrine gland whose duct does not branch.
Compound Gland
Exocrine gland with branched duct system.
Tubular Secretory Unit
Glandular end piece shaped like a tube; may be straight, coiled, branched.
Acinar (Alveolar) Unit
Rounded secretory end piece resembling a sac; common in pancreas, parotid.
Tubuloacinar Gland
Gland containing both tubular and acinar secretory portions.
Mucous Acini
Secretory units producing viscous, glycoprotein-rich mucin that hydrates to mucus.
Serous Acini
Secretory units producing thin, enzyme-rich watery fluid; cytoplasm basophilic.
Mixed Acini
Secretory units containing both mucous and serous cells; may show serous demilunes.
Myoepithelial Cell
Contractile stellate cell surrounding secretory acini and ducts; aids in expelling secretions.
Merocrine Secretion
Exocytosis of secretory product with no loss of cell membrane or cytoplasm.
Apocrine Secretion
Release of apical cytoplasm together with secretory product; e.g., ceruminous glands.
Holocrine Secretion
Discharge of entire cell contents following cell destruction; e.g., sebaceous glands.
Artifact
Minor structural distortion in tissue sections caused by preparation steps.
Longitudinal Section (l.s.)
Tissue slice cut parallel to the organ’s long axis.
Cross / Transverse Section (c.s. or t.s.)
Tissue slice cut perpendicular to the long axis of the organ.
Oblique Section
Tissue slice cut at an angle between longitudinal and cross sections.