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72 Cards in this Set
- Front
- Back
Describe clinical use for histology techniques
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Unfixed frozen sections are used in surgery when time is vital, but get lower resolution
Fixed samples have better resolution but require more time |
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Discuss reasons for and results of fixation
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Fixation terminates metabolism, prevents enzymatic self digestion, kills microorganisms, hardens tissue by cross linking and/or protein denaturation
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Describe common fixatives
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1.Formaldehyde- reacts with amino groups but POOR fixative of cell membranes
2.Glutaraldehyde- produces better fixation then formaldehyde but incompatible with some immuno and silver stains. Used for electron microscopy 3.Osmium tetroxide- excellent for electron microscopy, including membranes |
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Describe basic dyes
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Bind to ACIDS (basophilic structures) such as DNA, RNA, acidic sugars
Also called Nissl stains Examples- methylene blue, hemotoxilin |
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Describe acidic dyes
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bind to BASES (acidophilic structures), like cytoplasmic molecules, collagen, red blood cells
Example - eosin |
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What does Golgi stain bind to
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Binds to aldehydes in sugars, used to visualize neurons
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How does heavy metal stains work
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Heavy metals- lead and uranium- are used to bind to inside and outside of the cell membrane
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What does lipid bilayer composed of
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Phospholipids and cholesterol with embedded proteins
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What does cholesterol do for the membrane
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It stabilizes membrane fluidity
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What can proteins do after they are synthesized
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They can free float, channel in rough ER or transfer to smooth ER
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Name major types of membrane proteins
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Pumps - Na/K pump
Channel- glucose channel of muscle, select certain things to come in the cell Receptors- molecules bind outside, changes occur inside Linkers - anchors molecules down, collagen Enzymes - ATPase Structural- forms tight junctions |
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Heterochromatin
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dark clumps of highly coiled DNA, predominates in cells with low metabolic activity
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Euchromatin
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Pale, staining unwrapped and actively transcribing DNA
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Describe nucleus
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-surrounded by membrane
-EUKARYOTIC ONLY -nucleoplasm is fluid -nucleus active- light, non active - dark |
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Nucleolus
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DNA and ribosomal proteins associated with transcription to rRNA
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Pars granulosa
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Portion of nucleolus that stains LIGHTLY - contains actively developing ribososmes
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Pars fibrosa
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portion of nucleolus that stains DARK - inactive DNA and some recently translated RNA
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Nuclear membrane
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Two bi layer membranes
Perinuclear space between them, continuous with ER Nuclear lamina is scaffolding for chromosomes and nuclear pores During division nuclear envelope breaks up |
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Nuclear Pore
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-regulates bidirectional transport of molecules
-RNA transported out -water and small ions passively diffuse through pore |
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Rough ER
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Processing of proteins that will become
1. Inserted in membrane - integral membrane proteins |
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How are proteins transported
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Vesicles pinch off ER and transport proteins to Golgi
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Smooth ER
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NO RIBOSOMES (dont have ribosome docking proteins)
contains enzymes involved in LIPID synthesis, STEROID synthesis, GLYCOGEN metabolism and MEMBRANE sysnthesis In muscle take up and release Ca together with sarcoplasmic reticulum In liver contain cytochrome P450 and other detoxification enzymes |
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What is the signal for protein to go to lysosome
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Mannose phosphorylation
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Main function of Golgi apparatus
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Sorting of proteins
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Define pinocytosis
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Cell drinking, nonspecific ingestion of fluid and small molecules
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Phagocytosis
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Cell eating, ingestion of large particles, debris, bacteria and other foreign materials
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Endocytosis
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substances enter cell
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Exocytosis
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substances leave cell
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Endosomes
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In between proteins, also do sorting - separate receptor proteins for recycling
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Late endosomes
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Develop in lysosomes
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Describe Tay Sachs disease
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-caused by absense of lysosomal galactosidase ( beta hexosaminidase) in neurons
-GM2 ganglioside abnormally accumulates -children appear normal first, slower growth, changes in facial features,bone deformities, lose attained speech, mental retardation, finally death |
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Peroxisomes
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-contain hydrogen peroxide, very hostile environment
-degrade lipids (beta oxidation) -found in most cells but most in liver and kidney |
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Zellweger syndrome
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Dysfunctional peroxisomes
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Mitochondria
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contains its own circular DNA, ribosomes and proteins, has ability to divide
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Immunohistochemisstry
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1. Incubate tissue with Ab to specific molecule - Primary Ab
2.Wash off all Ab's that did not find target 3.Incubate with secondary Ab's that will recognize primary Ab's |
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Hybridization
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similar to immuno except that it uses single stranded DNA or RNA to find complementary nucleic acid
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Microtubules
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Nonbranching
Rigid Hollow Has MAP vesicular transport cilia and flagella mitotic spindle elongation, movement and shape |
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Intermediate filaments
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Intermediate in thickness between actin and tubulin
4 classes - keratins, vimentins, neurofilaments, lamins |
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G1 phase
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gather nutrients for DNA replication
Restriction point - sensitive to size, if DNA damaged, can send back to G0, or p 53 will initiate apoptosis |
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S phase
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DNA replication, damage checkpoint
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G2 phase
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DNA damage checkpoint, prepare for cell division
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p53
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tumor suppressing protein
becomes active if DNA damaged blocks cyclins blocks DNA synthesis initiates apoptosis |
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Factors that can trigger apoptosis
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TNF, lack of growth factor, DNA fragmentation
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Intermediate filaments
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Intermediate in thickness between actin and tubulin
4 classes - keratins, vimentins, neurofilaments, lamins |
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G1 phase
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gather nutrients for DNA replication
Restriction point - sensitive to size, if DNA damaged, can send back to G0, or p 53 will initiate apoptosis |
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S phase
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DNA replication, damage checkpoint
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G2 phase
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DNA damage checkpoint, prepare for cell division
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p53
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tumor suppressing protein
becomes active if DNA damaged blocks cyclins blocks DNA synthesis initiates apoptosis |
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Factors that can trigger apoptosis
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TNF, lack of growth factor, DNA fragmentation
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General characteristics of epithelium
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Closely apposed cells covering open surface
Functional and morphological polarity Resting on basement membrane |
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Functional classification of epithelium
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SURFACE E. - creates barrier - epithelium of skin, body cavities, inside of vessels, inside of hollow organs
GLANDULAR - secretory role - forming glands SPECIALIZED - sensory role- receptors for special senses |
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Morphological classification
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ACCORDING TO CELL SHAPE
Squamous Cuboidal COlumnar ACCORDING TO NUMBER OF CELL LAYERS Simple epithelium(one layer) Striated epithelium (multiple layers) |
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Domains of epithelial cell
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APICAL - microvilli, stereocilia, cilia
LATERAL - junctional complexes- occluding junctions, anchoring junctions, communicating junctions BASAL- basement membrane, cell to extracellular matrix junctions, plasma membrane infoldings |
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Microvilli
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Finger like cytoplasmic projections of apical surface
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Function of microvilli
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Increase cell surface
intestine- striated border kidney - brush border vary in length and sickness |
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Microvilli fine structure
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1. VILLIN at tip
2. TERMINAL WEB at base, horizontal network of actin filaments, spectrin cross links and anchors actin to plasma membrane, myosin and tropomyosin provide contractility 3. CORE OF ACTIN filaments between villin and terminal web, cross linked by fascin and fimbrin (gives support and rigidity), linked to plasma membrane by myosin I |
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Stereocilia
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Extremely long processes
Only in EPIDIDYMIS DUCTUS DEFERENS SENSORY (HAIR) CELLS OF EAR |
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Function of sterreocilia
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Increase cell surface
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Stereocilia fine structure
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1.NO VILLIN at tip
2. CORE OF ACTIN cross linked by FIMBRIN (support and rigidity),linked to plasma membrane by ERZIN 3. A-ACTININ - cross links actin filaments at stem and base of stereocilia |
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Cilia (Kinocilia)
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MOTILE PROCESSES - TRANSPORT
beat in synchronous pattern, wave of sweep In RESPIRATORY SYSTEM - transport mucus OVIDUCT- transport of egg |
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Sensory role of kinocilia
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Some cells contain single cilium - epithelial cells of rete testis, vestibular hair cells of ear
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Basal bodies
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dark staining band at the base of cilia
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Fine structure of kinocilia
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CENTRAL PAIR OF MICROTUBULES - partially enclosed in sheath, end at level of basal body, regulate movement
MICROTUBULE DOUBLETS - A MICROTUBULE 13 tubulin subunits, B MICROTUBULE - 10 tubulin structures. Also has ciliary dynein, nexin, radial spokes BASAL BODY- modified centriole, cilia grow from basal bodies |
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Lateral domain
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in close contact with neighbouring cells, forms interdigitations with some cells, has unique adhesion molecules that form junctions
show up in normal light microscopy |
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Fine structure of lateral domain
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ZONULA OCCLUDENS- impermeable, close to apical surface, prevents migration of apical proteins to lateral domain
ANCHORING JUNCTIONS - link cytoskeletons, can be found at lateral and basical domains, has zonula adherens and macula adherens COMMUNICATING JUNCTIONS - permits coordinated cell activity |
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Occluding junction- zonula occludens
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plasma membranes cells come in close contact, protein occludin is sealing protein
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Anchoring junction - zonula adherens
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belt like junction to zonula occludens
limited resistnace to stress |
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Structural components of basement membrane
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COLLAGEN - type IV collagen mostly, product of epithelial cells, short fillaments building basal lamina , also type VII collagen - binds basal lamina to underlying reticular lamina
PROTEOGLYCANS- high negative charge, regulation of ion transport through basal lamina LAMININ - cross shaped glycoprotein,links basal lamina to cell ENTACTIN and FIBRONECTIN - other glycoproteins, unknow function |
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What attaches actin filaments to basement lamina
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Integrins - anchoring proteins
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What attaches intermediate filaments to basement lamina
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hemidesmosomes
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Infoldings
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characteristic for kidney ducts and duct of salivary glands
contain mitochondria provide energy to active transport |
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What is the functional division of glandular epithelium
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EXOCRINE - releasing on surface - merocrine, apocrine, holocrine
ENDOCRINE - releasing secretion (hormones) to blood PARACRINE - releasing product to neighboring cells |