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Flashcards in Epithelium Deck (55):
1

Location of epithelial tissue

_Exterior surface _lines intestinal cavities _Secretory portion of glands & ducts

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Characteristics of epithelial tissue

_Mainly has an exposed free surface _cells are close together and have strong adhesion _Avascular: get nutrients through diffusion

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Apical Layer

_Touches the external aspect of the layer _Where secretory vesicles are located

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Microvilli

_Core formed by actin filaments bound by actin binding proteins _Anchored by lateral anchoring proteins (myosin I) to villin

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Villin

Amorphous apex that the actin filament are anchored to

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Stereocilia

_Modified microvilli _Actin filament core _long (sometimes branching) projections _absorption in epididymus, sensory receptors in the cochlea

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Cilia

_Move substances along the surface of the epithelium _Made up of axoneme and a basal body base

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Primary Ciliary Dyskinesia

_Genetic defect causing malformation of cilia skeleton _Uncoordinated or absent cilia beating _Signs: Dextrocardia, impaired skull air sinuses, lack of mucus removal from lungs, infertility

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Lateral Domain

Defined by the presence of cell junctions

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Terminal bars

Junctional complexes visible with a microscope

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Occluding cell junctions

_Typically apical portion of cell _ form sealing strands of transmembrane proteins of 2 adj cells _Typically in cells with secretory or absorption role

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Zonula occludens

_Only type of occluding junction _Virtually impermeable

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Anchoring cell junctions

_Provides mechanical strength and stability _Connects adj cells' cytoskeletons

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Adherens

_Anchoring junctions (Zonula & Macula)

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Zonula adherens

_belt-like junction that connect *actin* filaments _Actin-binding proteins: vinculin & _-actinin _Catenin (peripheral protein) _ Transmembrane link protein (part of Cadherin family)

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Cadherin Family

_Ca__ dependent protein that plays in important role in cell behavior control _Loss of protein associated with metastasis

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Macula Adherens

_Aka desmosome _Connects *intermediate* filaments _provides mechanical strength, particularly in skin _Desmoplakin: the intercellular plaque that the filaments of thru _Cadherins: transmembrane proteins

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Pemphigus

Autoimmune disease that attacks the desmosomes, preventing normal adhesion_causes blistering and skin falling apart

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Gap Junctions

_Allow diffusion of small molecules and ions b/t cytoplasm of adj cells for communication _Intercellular channels: where diffusion occurs _Connex*o*ns: pair forms a channel _Connex*i*ns: protein subunit (6=1connexon) _Typically occur in patches

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Basal Domain

_Faces the basement membrane _interacts with underlying tissue _Basement membrane + Anchoring junctions

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Basement membrane

_Separates epithelium from underlying connective tissue _Basal lamina + Reticular lamina

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Basal lamina

_Most external layer _Mostly collagen type IV and laminin

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Reticular lamina

_Deeper layer _Mostly thin collagen fibers

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Basement membrane anchoring junctions

_Focal adhesions _Hemidesmosome

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Focal adhesions

_Attach *actin* cytoskeleton to extracellular matrix _ Actin-binding proteins (Vinculin, _-actinin) attach to MF _Peripheral protein (talin): actin-binding protein to transmembrane protein _Transmembrane protein (integrin family)

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Hemidesmosome

_Connects *intermediate* filaments _Desmoplakin: the intermediate plaque that attaches to the ends of the IFs _Transmembrane protein (integrin family)

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Simple squamous

_Used as barrier, diffusion of oxygen/CO_ _Lining of vascular system, body cavities, parietal layer of Bowman's capsule, alveoli

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Endothelium

_Special simple squamous _lines the inner blood vessel walls and the heart

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Mesothelium

_Special simple squamous _covers internal organs

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Simple Cuboidal

_Barries (ducts), secretion (thyroid), absorption (kidney) _walls of ducts, kidney tubules, germinal epithelium of ovary, thyroid follicles

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Simple Columnar

_Non-ciliated: GI tract, gallbladder _Ciliated: oviduct lining _Can have striated(microvilli) border _Absorption, secretion, lubrication, transport

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Pseudostratified columnar

_Basal cells: rounded cells that do not reach the apical surface _Ciliated: found in respiratory tract _Non-ciliated: has stereocilia, found in epididymus (absorption)

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Stratified squamous

_Barrier _Keratinized: nucleus-lacking epithelial cells on apical side _Non-Keratinized: GI and vagina

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Stratified cuboidal

_Barrier/conduit _sweat glands

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Stratified columnar

_barrier, conduit _Larger ducts of glands (parotid/submandibular salivary glands)

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Transitional

_aka urothelium _only found in urinary system _has ability to stretch and relax

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Endocrine

_product *diffuses* to the intercellular space/underlying connective tissue _No ducts

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Exocrine

Secrete into ducts/spaces lined with epithelium

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Unicellular glands

Individual secretory cells within non-secretory epithelium

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Multicellular glands

_Glands composed of more than one cell _Secretory + duct

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Alveolar/Acinar gland

Shaped like a flask

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Tubular gland

Shaped like a tube (often mucous)

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Tubuloalveolar gland

Tube with a flask-shaped dilation

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Myoepithelial gland

_Contractile cells with contractile proteins (myosin) _contract to expel secretions out of gland _Sweat, salivary, mammary gland

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Merocrine gland

_Membrane bound vesicles take substances to plasma membrane (exocytosis)

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Serous product

_Thin, watery, protein-rich secretion _Acini are more rounded in shape _Pancreas/parotid salivary gland

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Mucous product

_Made of mucins: long chains of negatively charged carbs attached to a protein core _Lubrication and protection _Acini typically tubular _Goblet cells, soft palate glands, Brunner's gland

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Seromucous gland

_Both serous and mucous product _have mucous tubules capped with serous demilunes

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Apocrine

_Pinching of apical cytoplasm _Mammary glands

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Holocrine

_Whole cell goes through apoptosis to realize all contents _Sebaceous glands of the skin

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Carcinoma

Cancer from barrier epithelium

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Adenocarcinoma

Cancer from glandular epithelium

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Goblet Cells

Unicellular mucous glands present in GI tract and trachea, pale granular cytoplasm/arrowhead-shaped nuclei

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Crypts of Lieberkühn

Simple, tubular glands that extend to the lumen

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Brunner's gland

Branched tubular glands in the submucosa of the duodenum