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219 Cards in this Set
- Front
- Back
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1 dalton
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mass of a hydrogen atom
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1 micron
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one thousandth of a milimeter
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Light microscope magnifies up to
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x2,500 with .2 micron resolution
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EM magnifies up to
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x~500,000 with .1-.2 nm resolution
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what is the downside to EM?
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Cannot be used to observe living cells
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Bright field microscopy
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shows little detail unless it is stained
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phase contrast
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is usedul for ordered structures like mitotic spindles and striated muscle
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Nomarski
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differential interference contrast microscopy gives a three dimensional appearance to the cell
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dark field microscopy
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illuminates the cell from the side giving scattered light against a dark background
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Fluorescence microscopy
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a fluorescent molecule is tagges to an antibody to identify a specific molecule. Different colored labels can be used to see different molecules in the same view. Fluorescent molecules are excited by light of one wavelength and emit light at a different wavelength
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how to prepare a LM slide
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1, fix in buffered solution to preserve structures 2, wash in buffer dehydrate in ethanol then embed in was or plastic 3, slice sections 1-10 microns thick 4, stain with hematoxylin or other dye
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How to prepare a TEM slide
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fix and wash in buffer, post fix in heavy metal (osmium), dehydrate in ethanol, plastic, ultrathin sections, mount on copper grid, stain with heavy metals ***osmium, uranium, lead***
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Cell membranes are lipid and protein bilayers that
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serve as physical boundaries, enable cell-cell recognition, compartmentalize eukaryotic cells, attach to cytoskeleton and extracellular matrix, sites for receptor molecules, sites for biological reactions
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how was the mosaic aspect demonstrated?
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freeze fractured membranes. Frozen, sliced through blayer, pits and particles, metal replica of surface from acid dissolution
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How was the fluid aspect of the fluid mosaic model demonstrated?
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mouse and human cell fusion with different fluorescences showed lateral diffusion. Can also be seen with FRAP fluorescence recovery after photobleaching
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What slows lateral movement in the plasma membrane?
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1, contact with cytoskeleton 2, contact with extracellular matrix 3, contact with proteins of an adjacent plasma membrane 4, tigh junctions preventing lateral mobility
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oligosaccharides are attached to membrane proteins and lipds to
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facilitate in cell-cell recognition. E.g. in immunology and embryonic development
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The sides polarized sides of epithelial cells are
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the apical side (in contact with air or fluid), the basal surface (in contact with the basal lamina), the lateral surface (in contact with eachother by various junctions)
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What produces the ECM (extracellular matrix)?
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The ER and the Golgi
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What does the ECM consist of?
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Fibrous proteins embedded in a gel which resists compression. Fibrous proteins provide tensile strength (they resist stretching). Include collagen and laminin
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name five junctions types in an epithelial cell
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1. tight junction 2. adherens junction 3. desmosome 4. gap junction 5. hemidesmosome
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tight junctions aka zonula occludens
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occluding junctions, form a belt encriciling the inner lateral surface of epithelial cells, seal the plasma membranes, maintain polarity by disallowing lateral movement of key transport proteins
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adherens junctions aka zonula adherens
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anchored to actin filaments and form a continuous adhesion belt that encircles the inner surface of the cell, usually immediately below tight junctions, cadherens on the outside of cell join with cadherins with another cell
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desmosomes aka macula adherens
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spot welders, plaque like structure approximately 1 micron or less in diamter, bind esp where there is mechanical stress, cadhereins span the space between, plaques attach to intermediate filaments (often keratin)
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hemidesmosomes
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attach cells to the extracellular matrix, like half a desmosome, integrins span the plasma membrane, plaques still attach to keratin inside the cell
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gap junctions
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2-4 nm space that separates adjacent cells that arei n communication.6 connexins form an aqueous channel that opens and closes via rotation
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Endoplasmic Reticulum
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a network of membrane tubules and cheets in the cytoplasm. P to 10% of cell volume, produces proteins and lipids for organelles, plasma membrane, and export; makes phosphplopis to be added to the ER membrane (involves flippase)
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Smooth endoplasmic reticulum
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lacks ribosomes, produces steroids, detoxifies drugs, and sequesters CA ions in muscle cells
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Signal recognition particle
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free ribosomes ranslating proteins destine for the ER are picked up by the SRP and brought to ER. SRP receptor in the ER membran brings ribosome to translocation chaennl, translation continues into channel and the signal sequence is cleaved
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Transmembrane protein translation
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have an additional signal to stop transfer into the ER (an alpha helix anchors the protein) protein remains in membrane and signal sequence is cleaved off
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v-snares and t-snares
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v snares are on vesicles and t snares on the target membrane. They intertwine to fuse the vesicles with membranes
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what is the tripeptide sequence that queues glycosylation?
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asparagine-X-serine or asparagine-x-threonine
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Three sections of the golgi
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cis, medial, trans
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transport of vesicles from the golgi
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simultaneous two-way transport of COP-coated vesicles, forward (cis-med-trans) and backward (trans-med-cis)
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KDEL receptors
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in COP coated vesicles follow retrograde pathway all the way to the ER to return ER resident proteins that were budded off with vesicles. Retrieval mechanism
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functions of the stops along the antiretrograde pathway
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ER - oligosaccharides added, Cis and medial golgi can remove sugars, Trans golgi packages secretory proteins into secretory vesicles and sort them by destination
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clatherin
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joined via adaptin to cargo receptors, assemble on cytosolic surface and shape membrane into a pit, dynamin causes the coated pit to pinch off and form a vesicle
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what are the three pathways for a secreted vesicle after leaving the golgi?
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Signal mediate diversion to lysosomes, regulated secretion, constitutive secretion
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signal mediated diversion to lysosomes
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proteins tagged with a mannose-6-phsphate in the cis golgi. Signal binds to mannose-6-phosphate receptors in the trans golgi and directs these proteins specifically to lysosomes
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Regulated secretory pathway
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release of these vesicles is triggered by a hormone for concerted release
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constitutive secretory pathway
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products are immediately discharged at the cell surface
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phagocytosis
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cell engulfs entire cells or parts of cells. Pino cytosis is similar using small vesicles, non-selective uptake of extracellular material
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receptor mediated endocytosis
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uptake of specific molecules that bind externally, clatherin forms pit and dynamin pinches off, enzyme removes clatherine and vesicles travels to 1, lysosome 2, cytoplasm 3, pass unchanged through the cell
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lysosomes maintain a pH of ___ through the use of _____
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5, proton pumps
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lysosomes contain ____ to digest substrates
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enzymes like proteases, lipases, and phosphatases. Approximately 40
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synthesis and secretion of lysosomal enzymes
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Newly made lysosomal enzymes are glycolsylated in the EW, then undergo M6P modification in the golgi, they are then trafficked to a mature lysosome, low ph dissociates the M6P. But if goes to PM, M6P serves to restore some of the contents by reforming the vesicle
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lysosomal storage diseases (two)
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inclusion cell disease where without M6P, lysosomes are exported to the ECM results in coarse facial features, skeletal abnormalities, and retardation... and Tay Sachs where ganglioside accumulation results in retardation, blindness, and death
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Peroxisome
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produce hydrogen peroxide and contain catalase. Involved in detoxification and break down of fatty acids
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Zellweger's Syndrome
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results from peroxisomes lack key enzymes leading to accumulation of toxic molecules, heptomegaly, and high levels of iron and copper in the blood stream.
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neonatal adenoleukodystrophy
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very long chain fatty acids cannot be oxidized and so accululat in the brain destroying myelin sheaths and in the adrenal glands causing deficiency of adrenal steroid hormones
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important mitochondria features to remember
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double membrane, have their own circular DNA, replicate on their own, contain their own ribosomes, site of OXPHOS
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OXPHOS key facts to remember
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pyruvate --> acetyl CoA, products of Krebs are CO2, GTP, NADH and FAH2. electron tansport chain creates proton gradient subsequently used to power ATP synthase and form water
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glycolysis yields
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2 ATP and 2NADH
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2 pyruvate to 2 acetyl CoA yields
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2CO2 and 2NADH
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Krebs yields
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4CO2, 2 GTP, 6 NADH, 2FADH2
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Total yield of glycolysis
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6CO2, 2ATP, 2GTP, 10NADH (30ATP), 2 FADH2 (4ATP) =30-38ATP
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Leber's hereditary optic neuropathy
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maternally inherited form of blindness due to mutations in the optic nerve's mitochondria being mutated and deprived of ATP
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hsp40 chaperone protein
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helps with the translocation of protein precursors to the mitchodria (can't enter folded) so prevents from folding
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mitochondrial proteins
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signal sequence signal transfer, hsp40 kepps unfolded, binds to receptor on OMM, lines up with IMM receptor, enters, signal cleaved, folds
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Origin of epithelium
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ectoderm, mesoderm, and endoderm
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structure of epithelium
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made up of cells that are closely packed and arranged in a single or multiple layers and resting upon a basal lamina. Avascular so relies on subadjacent connective tissue for vascular support
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functions of epithelium
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covers external surfaces, lines internal surfaces, forms unicellular and multi-cellular glands
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3 apical surface specializations in epithelial cells
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Microvilli, sterocilia, cilia
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microvilli
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brush border, regular membrane infoldings, increases cell surface area, good for absorption and secretion
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stereocilia
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founs in parts of the male reproductive system including the vas deferens and epididymis, long actin filaments
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cilia
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found in the tracheal epithelium and oviduct, motility by active sweeping, membrane covered structures, 9+2 array of microtubules, move debris and mucus
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basal lamina
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basement surface. Three layers of electron density lamina lucida, lamina densa, lamina lucida. Collagen IV
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Basal infoldings
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invaginations of the basal lamina on cells with important rolse in regulated transport. Mitochondria likely to be found nearby
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what are the 8 types of epithelium?
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simple squamous, simple cuboidal, simple columnar, simple, pseudostratified, stratified squamous, stratified cuboidal, stratified columnar, stratified transitional.
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simple squamous
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thin layer of flat attenuated cells. Examples: lining of blood vessels, bowman's capsule in kidney nephron, pulmonary alveoli
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simple cuboidal
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cells are square in profile. Examples: glands, thryroid, tubules in kidney
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simple columnar
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cells are tall and rectangular in profile, nuclei are usually in basal region of the cytoplasm, sometimes have goblet cells. Example: lining of the digestive tract
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Pseudostratified columnar
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All cells contact the basal lamina but not all reach the luminal surface, cells vary in shape. Example: lining of the conducting airways, male reproductive tract
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Stratified squamous
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squamous cells at luminal surface, maybe keratinized or nonkeratinized, basal layer is mitotically active. Examples: epidermis, esophagus, tongue, oral cavity, vaginal lining
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stratified cuboidal epithelium
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uncommon, ovarian follicles and sweat glands
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stratified columnar
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uncommon, large excretory ducts of sweat glands
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Transitional epithelium
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apical surface cells are dome-shaped when relaxed, flatten when organ is distended, urinary tract lining: bladder and ureter
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Gland formation
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gland are epithelial cells that are specialized for secretion. Exocrine and endocrine
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kinds of exocrine glands
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simple tubular, simple extended tubular, simple branched tubular, simple branched acinar, compound tubuloaciner, compound tubular, compound acinar
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goblet cells
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unicellular exocrine glands, look like spheres with a stem
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endocrine glands
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prodcts are hormones and the target cells are located at some distance fromt eh gland cell
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how many base pairs in a nucleosome and a linker stretch?
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146 and 50 respectively
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nuclear envelope has an inner and outer membranes that are continuous at the ___
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nuclear pores
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transport in the nuclear envelope
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small molecules go through the pores and are regulated by proteins. Larger molecules have signal sequences that require active transport, their signal sequences stay on them
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Lamins form the nuclear lamina
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type of intermediate filament, fibrous layer in which the lamins form a lattice, help determine nuclear structure, anchor interphase chromosomes at their telomeres, defective lamina causes progeria
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how are ribosomes made?
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rRNA is synthesized as a single molecule in the nucleolus and is cut up and combined with ribosomal proteins in the assembly of ribosomal subunits in the nucleus… exported to cytosol
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cell cycle phases
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G1, S, G2, M
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what happens in late G2 to cause mitosis?
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phosphorylation causes chromosomes to condense, spindle formation, and breakdown of the nuclear lamina
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When are chromosomes replicated?
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during S phase
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Replication of the centrioles and centrosome
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G1- centrioles move apart, S new centrioles grow at right angle, G2 complete their growth. Ready for mitosis
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Three types of spindel micro tubules
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aster, overlapping, kinetochore. Definted by the location of their + ends: cortex, equator, and kinechores respectively
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prohpase
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chromatin condenses, centrosome complexes move to ends of cell, mitotic spindle forms
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___ microtubules pull and ____ microtubules push
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astral, overlapping
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prometaphase
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nuclear envelope is disrupted to allow microtubules to access the chromosomes, nucleolus disappears, kineochores assemble and bind to microtubules
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how to kinetochores work?
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they are plaques at centromere, collar attaches to fibrils and holds the tubule in place, dynein attached to collar pulls the kinetochore towards the minus end of the microtubule
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metaphase
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chromosomes align at the metaphase plate
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anaphase
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kinetochores separate and pull apart chromatids (anaphase A) and chromosomes move to opposite poles from overlapping MT sliding (anaphase B) astral MT's contribute by pulling at cell periphery
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telophase
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chromosomes begin to decondense to form chromatin, nuclear lamina reforms, nuclear envelope reforms, nucleolus reappears, kinetochore microtubules disappears. Driven by dephosphorylation.
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cytokinesis
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cytoplasm divides by process called cleavvage, contractile ring of actin and myosin around remaining overlapping spindle
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necrosis
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necrosis occurs when cells are damaged, swell and burst. Initiates an inflamatory response
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apoptosis
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nuceus condenses in an organized manner and endonucleasses break down DNA, loses adhesion, shrivels, and is digested by a macrophage
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describe the cytoskeleton briefly
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links organelles and membrane systems, framework for cellular activities, generates force, serves in morphogenesis. Consists of microtubules, actin filaments, and intermediate filaments
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intermediate filamens
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monomer: rod with N and C terminuses. Form dimers, dimers stagger to form tetramer, 8 tetramers associate to form an intermediate filament. Noncovalent bonds.
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amyotrophic lateral sclerosis
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amnormal neurofilaments (IF) cause damage to axons
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desmin-related myopathy
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desmin is IF of muscle cells near the Z line. Muscle fibers become disorganized because the IF not strong enough
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epidermolysis bullosa simplex
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defective keratin (IF in epithelia) causes blisters because unable to resist pressure
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progeria
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nuclear lamina (nuclear IF) cause premature ageing in children
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Microtubules
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involved in morphogenesis and mobility, wall consists of 13 protofilaments, comprised of tubulin dimers alph and beta, polar (beta is plus end)long unbranched cylinders
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Kinesis and dynein
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motor molecules associated with Mys. ATPases that convert ATP to mechanical energy. Dynein moves toward the minus end and Kinesin moves towrd the plus end.
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MTOCs
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Microtubule organizing centers
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Taxol
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binds to microtubules, assembly occurs in the absence of disassembly, excessive microtubules cannot function.
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Colchicine, vinblastin, and vincristine
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bind to tubulin dimers and disassembly occurs in absence of assembly
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F-actin and G-actin
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F-actin is formed by polymerization of G-actin, ARPs nucleate F-actin
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myosin
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motor molecule associate with actin. ATPase to mechanical energy. Move toward the plus end with only one exception
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charcot-marie-tooth (CMT) neuropathy
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involves mutation of a kinesin in axons. Interupt transport of neurotransmitters. Axonal degeneration
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retinitis pigmentosa
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kinesin defect interupts transport in retinal cells
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lidocaine
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inhibits kinesin movement on acons and stops transport of neurotransmitters
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herpes uses ____ to move along____
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kinesisn, microtubules
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cilia motility
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the micro tubule doublets are connected to the ardial spokes and eachother by nexin and dynein arms. Dynein causes the microtubules to slide by eachother and the nexon anchors them to convert the sliding to bending
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primary cilia
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lack dynein and do not move. Are sensory and have signaling proteins instead
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origin of connective tissue
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mesoderm
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functions of connective tissue
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support, connect, protect, and bind to other tissues. Matrix for intercellular communication. Site of tissue reactions. Insulation and thermoregulation. Vascular support to other tissue
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general characteristics of connective tissues
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consists of a variety of cells embedded in an extracellular matrix
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What is in the extracellular matrix?
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water, electrolytes, minerals, wastes, nutrients, and chracteristic macromolecules(glycoproteins and proteoglycans) and fibers
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categories of connective tissue based on the amount of fiber in the matrix
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loose CT (areolar), Dense regular connective tissue (tendon and ligament), and dense irregular (dermis and periosteum)
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list some special connective tissues
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Adipose, embryonic, elastic, reticular, cartilage and bone, blood
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Ground substance
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contains glycoproteins (gP) and proteoglycans (pG)
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glycoproteins
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proteinwit hbranched carbohydrates: fibronectin, laminin, chondronectin
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proteoglycans
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core protein with GAGs. GAG examples: heparan, keratin sulfate, dermatan sulfate, chrondroitin sulfate
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hyaluronic acid
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part of the matrix, a GAG that doesn't bind to protein, aggregates and binds to water to lubricate joints
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connective tissue cell types
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fibroblasts, macrophages, pasma cells, mast cells, adipose cells
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fibroblasts
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stellate shaped, synthesize fibers and macromolecules
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macrophages
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pagocytic, derived from blood cells, irregular shape, immune, antigen-presenting cells
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plasma cells
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eccentric nuclei characteristic. Synthesize antigen specific antibodies. Derived from B-lymphoscytes
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mast cells
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contain granules that store chemical mediators of inflamation like histamine, receptos for IgE made by plasma cells
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adipose
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white unilocular. Insulator and shock absorber. Energy depot. Brown fat has thermogenin (uncoupling protein)
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Connective tissue fibers
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collagen for tensile strength and elastin for elasticity
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types of collagen
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type I (dermis, bone, dentin) Type II (cartilage) Type III (reticular) Type IV (basal lamina)
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collage synthesis
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1. Pre-Pro-collagen sequestered in ER 2. Pro & Lys are hydroxylated, triple helix formed with registration peptides 3. procollagen secreted to ECM 4. registration peptides cleavedandnow insoluble 5. collagen molecules aggregate along the registration lines to form fibers
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Elastin synthesis
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secretion of elastin precursor, tropoelsastin, cross-linking of tropoelastin molecules occurs desmosine and isodesmosine. Fibrilin 1, a glycoprotein provides the scaffolding to form fibers
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Marfan Syndrome
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mutation of the fibrilin gene that results in abnormal elastic fibers. Bulging of the aorta and dislocation of the lens of the eye
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Reticular
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Type III collagen arranged in a meshlike network. Supporting function for highly cellular organs like lymph nodes, liver, and spleen. Can be identified by silver staining.
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Origin of cartilage
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derived from mesoderm
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Function of cartilage
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shock absorber flexible/cushioning and support
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General characteristics of cartilage
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consists of an avascular matric with chondrocytes ouse in cavities called lacunae. Cartilage is surrounded by vascularized perichondrium or synovial fluid
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cartilage varieties
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Hyaline, Elastic, fibrocartilage
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Hyaline cartilage
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most common, joint surfaces, nose, larynx, trachea, bronchi, embryonic skeleton. Homogenous glassy appearance. Contains type II collagen, hyaluronic acid, and proteoglycans and chondronectin
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elastic cartilage
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where support and flexibility are needed. Pinnae of the ear and epiglotis. Perichondrium and enlarges by appostiional growth. Black hairy appearance around lacunae
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Fibrocartilage
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capsules and ligaments of joints. Support and tensile strength. Organized like dense, regular connective tissue. No perichondrium. Rows and bundles. Annulus fibrosus of intervertebral discs and pubic symphysis
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What are the two types of cartilage growth?
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Appositional and interstitial growth
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appositional growth
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surface growth which occurs at the cartilage surface between the perichondrium and the previously formed cartilage. Chondrenergic cells>chondroblasts. Secrete matrix.encase in lacunae .become chodrocytes
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intertitial growth
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proliferation of existing chondrocytes. Occurs from within. Young chondrocytes replicate via mitosis and secrete matrix to separate
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Origin of bone
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mesoderm (or neural crest for dermal flat cranial bones)
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functions of bone
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protect visceral organs, provide for locomotion via joints and muscle attachment sites, matrix serves as calcium depot, marrow is site for hematopoiesis
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general characteristics of bone
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composed of mineralized matrix and yet is a dynamic tissue that can be repaired and renewed
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divisions of the skeleton
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axial=skull vertebral column, sternum. Appendicular= pectoral and pelvic girdles plus limb bones
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types of bone
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compact and spongy. Compact made of osteons. 80% of adult skeleton. Spongy is delicate lattice of thin trabeculae, hematopoeitic tissue in cavities- flat bones, skull, sternum, and epiphyses
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Bone matrix
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type I collagen and osteocalcin and sialoprotein in the organic portion. Inoragin contains mineral deposits of hydroxyapatite crystals (calcium phosphate)
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bone cells
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osteoprogenitor cells, osteoblasts, osteocytes, osteoclasts
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osteoprogenitor cells
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spindle-shaped connective tissue cells that are derived from embryonic mesenchyme. Near bone surface, inner portion of periosteum. Differentiate to osteoblasts
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osteoblasts
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active secretory cells found at the margins of growing bone, once in lacunae become osteocytes
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osteocytes
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mature bone cells. Have cellular processes that radiate from the cell boddies and form gap junctions with eachother to exchange nutrients
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Osteoclasts
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multinucleated, derived from blood monocytes, resorb bone matrix and release calcium to blood. Ruffles border faces bony matrix
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Two ways that bone develops
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intermembranous (within mesenchyme) Endochondral Ossification (within cartilage model)
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Intramembranous ossification
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direct deposit of matrix by osteoblasts in mesenchyme. Occurs in dermal bones
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Endochondral ossification
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involved progrssive replacement of hyaline cartilage model with bone. All bones below skull and clavicles
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what are the five distinct ossification zones
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resting cartilage, proliferating cartilage, hypertrophy, calcifying cartilage, ossification
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resting cartilage
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chondrocytes are at rest in hyaline cartilage area
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proliferating cartilage
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chondrocytes multiply and become arranged in parallel columns. Main zone responsible for bone growth
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hypertrophy
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chondrocytes hypertrophy, increase in size, stop secreting collagen and proteoglycans and begin secreting alkaline phosphatase
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calcifying cartilage
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chondrocytes die and matric calcifies with mineral deposition
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ossification
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osteoblasts deposit bone matric proteins in the areas being vacated by calcified cartilage
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primary bone
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irregular arrangement of collagen fibers, large numbers of osteocytes and low mineral content. It is remodeled and replaced by secondary bone. Later replaced by secondary mature bone which is either spongy or compact
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secondary bone
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chemically mature. Spongy or compact.
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osteons
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consist of cylindrical concentric arrays of rings of bone matrix (lamella) arranged around a central canal (the haversian canal).
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lamella
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contain lacunae with osteocytes connected through canaliculi around the haversian canal.
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haversian cannal
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carry nerves, blood and lymoh vessels along the long axis of bone
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volkmann's canals
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carry vessels between the marrow cavity. The haversian canals, and the periosteum
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Origin of muscle
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mesoderm
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Function of muscle
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permits movement in skeletal system, visceral organs, heart
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muscle cells also known as
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myofibers
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Development of skeletal muscle
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derived somites that give rise to myoblasts from the myotome portion
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skeletal muscle organization
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gross>fasicle (tissue level)>fiber (cell level) >Fibril (organelle level) >Filament (molecular level)
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muscle fiber is wrapped in ____ and a fascicle is wrapped in ____ and a gross muscle is wrapped in _____
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endomysium, perimysium, epimysium (superficial fascia)
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appearance of skeletal muscle in micrscope
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longitudinal section of fibers show striation and peripheral nuclei, crossection show peripheral nuclei
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smooth muscle histology
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smaller than skeletal, not striated, central nuclei in crosssection. Usually two bands for peristalsis: longitudinal surrounds circular in gut
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cardiac muscle
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branches, central nuclei in cross, intercalated disks but striated too.has a zigzag pattern where gap junctions meet
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purkinje fibers
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SA or AV nodes. Specialized myocardial fibers because they conduct electical impulses without synapses. Coordinate contractions in heart. Look light stringy and loose next to the cardiac muscles
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function of nervous system
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coordinate and regulate
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structure of nervous system
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key cells are specialized to communicate with speed and accuracy input>integrate>output
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origin of nervous system
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ectoderm
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3 neural tube defects
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anencephaly, encephalocele, spina bifida
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CNS
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brain and spinal cord
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PNS
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Autonomic (sympathetic and parasympathetic) Somatic (motor and sensory)
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Spinal cord
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deep matter gray, white is superficial, dorsal root the narrower horn. Cell bodies in gray matter
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dorsal root ganglion
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cell bodies look like fried eggs. Surrounded by sattelite cells
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Cerebral cortex
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gyri (raises) and sulci (grooves) outside is gray matter and inside is white. White matter is actually darker on slide.
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cerebral cortex layers
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6 layers. Molecular, external granular layer, external pyramidal layer, internal granular layer, internal pyramidal layer, polymorphic or multiform layer. Lgranular refers to mostly stellate neurons and pyramidal to pyramindal neurons
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pyramidal neurons
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80% of neurons in cortex. Release glutamate (major excitatory component of the cortex) output neurons that transmit signals to other parts of the CNS.
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cerebellum
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3 layers: molecular, purkinje cell layer, granular layer
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molecular layer of the cerebellum
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filled with very fine axons and dendrites from the cells below. Few neurons basket cells and stellate cells scattered
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purkinje layer of the cerebellum
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single layer of giant purkinje cells. Giant molecules that send their dendrites into the molecular layer and their axons into the white matter
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granular layer of the cerebullum
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very small neurons, granule cells, about the size and shape of lymphocytes. Axons extend into the upper layer of molecular
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Meninges three layers
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PAD, pia mater, arachnoid, dura mater. System of membranes to envelop the CNS
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dura mater
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outermost layer of the meninges made up of very dense fibrous tissue that is fairly impermeable and tough
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arachnoid
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middle layer of the meninges. Very loose and filled with CSF.
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pia mater
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delacate layer of collagen makes the inner most layer of the meninges
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ependymal cells
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in some places these cells form the choroid plexus to create CSF. Lines the lateral ventricles, third ventricle, and the aqueduct to the fourth ventricle to the central canal. Cuboidal or low columnar
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types of neuron structure
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unipolar and multi polar. Multipolar is the traditional form, uni polar have the denrite and axon enter the cell body through the same conduit
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three types of neurons
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sensory, motor and interneurons
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glial cells
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support cells in the nervous system :oligodenrocytes (schwann in PNS), Microglia, Astrocytes, Ependymal calls
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astrocytes
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only in the CNS, largest of the neuroglia, ancho neurons to blood supply. Blood brain barrier. Provide structural support, connect to eachother via gap junctions, supply glucose to nerves, regulate capillary blood flow via production of arachidonic acid metabolites. look dark and branchy spindery on slides
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microglia
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specialized brain macrophages derived from blood borne monocytes mesodermal origin. Phagocytic . Elongated bodies, elongated nuclei, dense chromatin, relatively few processes
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Oligodendrocytes
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form myelin sheaths of CNS neurons
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Schwann cells
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myelin cells for PNS. One axon per cell but multiple cells on axon. Looks like dark tree rings around the axon
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non myelinated nerve fibers
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axons small in diameter are usually non myelinated. CNS and PNS. Post ganglionic autonomic nervous sutem are non-myelinated and their axons are enclosed in simple clefts of schwann cells
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connective tissues around nerve fibers
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individual axon is surrounded by endonurium, bundle of axons is surrounded by perinuriumn whole nerve bundle is surrounded by epineurium
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Where can you find the myenteric plexus?
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between the longitudinal and circular layers of the smooth muscles in the intestines
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Where can you find the submucosal plexus?
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between the circularsmooth muscle and the epithelial layers
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