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41 Cards in this Set
- Front
- Back
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Tight Junctions |
(Zonula Occludens) Compartmentalize the cell. Keep fluids from entering or exiting between lumen and cell. Acts as a waterproof belt. No ions/molecules through paracellular route between cells |
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Zonula Adherens |
adhering junctions (belt), below tight junctions, act to stabilize the cell. Cadherins connect to actin filaments |
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Desmosomes |
Below Zonula Adherins. Also contain cadherins, but they connect to intermediate keratin filaments. Also function to stabilize the cell |
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Gap Junctions |
Allows communication between the cells in the same layer |
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Hemidesmosomes |
anchor the cell to the basement membrane specifically the basal laminae |
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Function of Basement Membrane |
Separates epithelium from supporting CT layer, differentiates cell tissue, helps polarize the cell, provides an anchor for all cells of the epithelium, selective barrier for epithelium |
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Layers of Basement Membrane |
cell membrane --> basal lucida, basal densa, basal fibroreticularis |
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Apical Membrane Specialization |
Microvilli, Stereocilia, Cilia |
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Microvilli |
Appear as Brush Border with LM, line intestinal lumen, increases surface area and aids in absorption. Approx 1/10 micron wide, and one micron long, made up of actin filaments, and connects to terminal membrane |
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Stereocilia |
sensory in inner ear, and luminal epithelium of cells of epididymus, up to 120 um long, typically by themselves, visible with EM, made up of actin, connects to terminal membrane |
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Cilia |
5-10 um long, twice as thick as microvilli, lines respiratory epithelium, undulating motion moves fluids in one direction, made up of microtubules in axoneme with 9+2 orientation, dyenin acts as motor, LM can see them as clusters, difficult to find alone, connects to basal border |
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Non-motile cilia |
"Primary cilia" - microtubules, 9+0 arrangement, found in mechanosensory or chemosensory structures, exist in singles throughout many types of epithelial cells, difficult to find even with EM |
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Structures associated with a polarized cell |
basement membrane orients cell, plasma membrane organized into apical and basolateral domains - and the two domains have different functions + protein and lipid compositions |
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What does polarized mean for a cell? |
a cell is said to be polarized if its different structures reside in different locations throughout the cell to facilitate the many different functions of a cell |
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Why do you stain different secretions? |
Helps you differentiate between types of secretions. Mucus stains pale with HE and magenta with PAS. Serous stains more pink and appears to have a murky cytoplasm |
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Exocrine Glands |
secretes molecules out its apical side onto free surface or into a lumen. Most have ducts three types: mesocrine - small particles, apocrine - larger particles, holocrine - explode to release. Ex: Goblet cell in respiratory tract Ex: mucus secreting cells in stomach secrete directly onto free surface (rare - normally ducts) |
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Endocrine Glands |
Secrete out their basal membrane into tissues, to be absorbed by blood vessels and carried to desired target, secretions referred to as hormones |
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Simple Sqamous |
nucleus bulges, typically in mesothelium, lines pleural cavities (potential spaces), also found in endothelium (lines bv) |
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Simple Cuboidal |
associated with secretions and absorption, lines kidney tubules, parenchyma of liver, central nucleus and cube shaped |
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Simple Columnar |
Lines lumen of intestine |
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Pseudostratified Columnar |
internal lining of trachea |
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keratinizing stratified squamous |
on epidermis - skin subject to abrasions squares develop on outer layer - lack nucleus |
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nonkeratinizing stratified squamous |
found on moist surfaces |
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Stratified cuboidal |
rare - immature ovarian follicles, ducts of some glands |
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Stratified columnar |
rare - some glandular ducts |
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transitional epithelium |
urinary tract |
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General Features of Epithelium |
cells are contiguous with intercellular space, avascular, joined by cell to cell junctions, attached to basement membrane, supported by underlying CT, often polarized, one free surface (except endocrine glands) |
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Phase Contrast |
useful for looking at live cells or tissues, tissue cultures, sperm or embryo, don't have to kill specimen, no staining |
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Magnetic Resonance Imaging |
(~50 microns), decent resolution, creates 3D image, need to fix, but no stain, works on water content, can use on live animals |
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Dark Field |
good for urine crystals |
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Confocal Laser Light |
3D image and computer processed, with fluorescent imaging |
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Blood smear |
fix, don't section, stain |
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Sample Prep for LM |
fix (right away) with formaldehyde usually embed in paraffin wax after dehydrating section and lay on glass slide stain with hematoxylin and eosin |
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Hematoxylin |
Basic stain that binds acidic structures like DNA and RNA, stains blue, outcompetes eosin in nucleus so it often appears blue or purple |
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Eosin |
acidic stain that binds basic structures like protein in the cytoplasm, stains red |
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TEM sample prep |
Fix with glutaraldehyde Embed in plastic Section 40 nm thick and put on metal grid stain with heavy metals -osmium, lead, uranium
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Condenser |
substage, focuses light on small area of specimen, |
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Condenser Diaphragm |
attached just below condenser lens, aperture can be adjusted to control diameter of cone of light entering condenser, should be left in highest position -affects contrast and resolution of image |
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Binocular head |
holds 2 oculars (eyepieces) |
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Focusing image for both eyes |
close left eye, use specimen focusing knobs to focus image for your right eye. Then open only left eye and focus by rotating the ring at the base of the left eyepiece
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Condenser focusing knob |
aperture smaller contrast increases resolution decreases light intensity decrease |
