Exam 1 Microanatomy Thread Flashcards

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1
Q

Phase Contrast

Microscopy

A

Small differences in refractive index ⇒ difference in contast.

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2
Q

Darkfield Microscopy

A

Specimen illuminated at an angle.

Curved surfaces scatter light.

Increases contrast of small objects in unstained specimen.

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3
Q

Polarizing Microscopy

A

Only rotated light visible.

Useful for visualizing structures that are arranged in a cystalline or paracrystallin array.

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4
Q

Confocal Microscopy

A

Opectical section of unsectioned specimen.

Laser excits cells in thin plan.

Out of focus regions are excluded ⇒ sharp image.

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5
Q

Hematoxylin & Eosin

A

Stains according to net charge at pH of staining solution.

Hematoxylin (+) charge so stains (-) charged tissues ⇒ basophillic

DNA/RNA

Proteoglycans & GAGS

Nucleus/Nucleolus

Ribosomes and RER

Eosin is (-) charged and stains (+) charged tisues ⇒ acidophillic

Mitochondria

Lysosomes

Erythrocytes

Collagen

Secretory vacuoles

Cytosol (proteins)

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6
Q

Trichrome Stains

A

Stains collagen

Masson trichrome ⇒ greenish blue

Mallory trichrome ⇒ sky blue

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7
Q

Elastic Stains

A

Aldehyde fusion

Orcein

Weigert’s elastic stain

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8
Q

Silver Stains

A

Reticular Fibers

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9
Q

Carbohydrate Stains

A

Periodic acid-Schiff (PAS)

Best’s Carmine

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10
Q

Lipid Stains

A

Oil Red O

Sudan black

Osmium tetraoxide

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11
Q

Stains Summary

A
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12
Q

Glycocalyx Funtions

A
  • Recognition
  • Enzymes
  • Immune recognition signals
  • Receptors
  • Transporters
  • Components of channels
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13
Q

Inclusions

A
  • Glycogen
    • No membrane
    • PAS or Best’s Carmine stains
  • Lipid droplets
    • no membrane
  • Lipofuschsin
  • Melanosomes
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14
Q

Nucleolus

A

Formed around nucleolar organizer regions (NOR).

Assembles signal recognition particles (SRPs)

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15
Q

Nucleus Transport

A

Nuclear pores are open aqueous channels ⇒ small (9-11nm) molecules passively diffuse

Larger proteins with nuclear localization signal (NLS).

Work with Exportins and Importins

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16
Q

Nucleus and Cell Division

A
  • Lamins phosphorylated ⇒ nuclear lamina and pore complexes disassembled
  • Dephosphorylation of lamins ⇒ repolymerize on chromosomes
  • Vesicles fuse around chromosomes or groups
  • Chromosomes come together, membranes fuse into one
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17
Q

Mitochrondria Function

A

Calcium sequestration

Apoptosis role

Thermogenesis

Energy generation

Enzyme histochemistry with succinic dehydrogenase.

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18
Q

RER

A
  • Protein synthesis and modification
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19
Q

SER

A
  • lipid and steriod synthesis
  • detoxification of lipid soluble drugs and toxins
  • sequesters Ca2+
  • role in glycogen metabolism
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20
Q

Golgi

A

Proteins/Lipids made in ER modified and sorted in golgi.

Large cytocentrum/centrosome ⇒ active golgi

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21
Q

Lysosomes

A

ID with acid phosphatase

Primary ⇒ enzymes, no substrates

Secondary ⇒ active enzymes and substrate

Tertiary ⇒ little or no rsidual enzyme activity, undigested substrates

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22
Q

Peroxisomes

A

Oxidation of long-chain fatty acids, bile acids, ethanol, and cholesterol.

ID with catalase.

Some with crystalloid of urate oxidase but not humans.

Formed de novo via pre-peroxisomal vesicles from ER

or from pre-existing peroxisomes via fission mediated by Pex proteins or peroxins

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23
Q

Cytosolic Protein Filaments

Overview

A
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24
Q

Microtubules

A
  • Filaments formed of heterodimers
    • Beta tubulins at (+) end
    • Alpha tubulins at (-) end
  • (-) end of the MT centralized near the nucleus at the MOC
  • Dynamic instability
    • growth and shrinkage at either end but more easily at (+) end
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25
Q

Microtubule Associated Proteins

(MAPs)

A
  • Organize microtubules
  • Stabilize, anchor, and space MTs
  • Regulate MT interactions with other elements
  • Regulate MT stability and dynamics
  • Ex. Tau, MAP1A, MAP2, MAP4, Katanin
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26
Q

Tau & Alzheimer’s Disease

A
  • Tau modulates stability of axonal microtubules
  • Hyperphosphorylation of Tau can result in disassembly of microtubules
  • Hyperphos tau form complexes ⇒ neurofibrillary tangles
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27
Q

Microtubule

Motor Proteins

A

Dyneins ⇒ move from + to - ends

Kinesins ⇒ move from - to + ends

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28
Q

Mitotic Spindle

A
  • Chromosome kinetochores captured by (+) end of MT
  • Moved to poles by MT dynamics and motor proteins
  • Spindle pole (aster) and spindle fibers allow for seperation of daughter chromosomes and daughter cells.
  • Chromosome-located kinesin help draw daughter chromosomes to spindle pole
  • Spindle fiber kinesins push daughter chromosomes apart
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29
Q

Microtubule Organizing Center

(MTOC)

A

Centrosome is the main MTOC.

  • Site of nucleation
  • γ-tubulin is only found in centrosome
    • required for nucleation
  • Nucleated at minus end
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30
Q

MT

Accessory Proteins

A

Anchor MT

Sever and release MT from centrosome

Provides scaffolds and adaptors for other proteins to link to centrosome

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31
Q

Centrioles

A
  • Embedded in centrosome
  • Organize centrosome (pericentriolar) matrix
  • Become basal bodies in cilia and flagella
  • Proximal part of lumen lined by α-tubulin
    • provides template for nucleation and arrangement of MT triplets
  • Distal part of lumen with centrin
  • Proximal and distal connecting fibers connect pair
  • 9x3
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32
Q

Basal Bodies

A
  • Formed from centrioles
  • Located at base of cilia and flagella
  • 9x3+0
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33
Q

Motile Cilia and Flagella

A
  • 9x2+2 arrangement
  • Ciliary dynein provides movement
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34
Q

Nodal cilia

A

Found in embryo @ gastrulation

9x2+0

beat clockwise

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35
Q

Primary Cilia

A
  • Non-motile
  • Found on almost all eukarytoic cells
  • 9x2+0
  • Act as mechanosensors and chemosensors
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36
Q

Keratins

A

Intermediate filament specific to epithelial cells.

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37
Q

Vimentin

A

Intermediate filament specific to fibroblasts and chondrocytes and other cells of mesenchymal origin.

38
Q

Desmin

A

Intermediate filament specific to myocytes.

39
Q

Glial fibrillary acidic protein

(GFAP)

A

Intermediate filament specific to glial cells

40
Q

Neurofilaments

A

Intermediate filament specific to neurons

41
Q

Nuclear lamins

A

Intermediate filament specific to the nucleus rather than cell specific.

42
Q

Microfilaments

Characteristics

A
  • Filamentous acid (F-actin)
    • globular/G-actin monomers for a two stranded helix polymer of F-actin
  • Free G-actin can be found in the cytoplasm
  • Dynamic and polarized
    • Barbed end / (+) end ⇒ fast growing
    • Pointed end / (-) end ⇒ slow growing
  • In non-muscle cells associated with non-muscle myosins ⇒ movment of cargo or microfilament sliding
  • In muscle cells, actin associated proteins stabilize polymerized actin to form microfilaments
    • Interact with thick filaments containing myosin to cause contraction
43
Q

Functions of Microfilaments

A
  • Structure of cell cortex
  • Core of microvilli
    • Anchor microvilli into terminal web
  • Major component of terminal web
    • Cell-cell attachment via zonula and fascia adherens.
  • Cell movement
    • filopodia, microspikes, lamellipodia
    • attach cell to substratum via focal adhesions
  • Form intracellular stress fibers (“muscles”)
  • Contractile ring during cytokinesis
44
Q

Cell Adhesion Molecules

(CAMs)

A

Transmembrane proteins that mediate cell adhesion.

4 families:

  1. Cadherins
  2. Immunoglobulins
  3. Selectins
  4. Integrins
45
Q

Cadherins

A
  • Calcium dependent
  • Homotypic binding
  • Large role in cell-cell adhesion
  • Involved in epithelial-mesenchymal transition
  • Several tissue specific families
  • Concentrated at adherens junctions
    • Actin ⇒ catenins
46
Q

E-Cadherins

A

Associated with epithelial cells

47
Q

N-cadherins

A

Associatd with CNS, skeletal and cardiac muscle

48
Q

P-cadherin

A

Associated with placenta

49
Q

Selectins

A
  • Calcium dependent
  • Bind cells via carbohydrate residues on opposite surfaces ⇒ heterotypic binding
  • Several varieties:
    • L (leukocytes)
    • E (endothelial)
    • P (platelet)
  • Involved in lyphocyte homing mechanisms
  • Involved in inflammation
50
Q

Immunoglobulins

A
  • Calcium independent
  • Adhere to one another via disulfide bonds ⇒ homotypic
  • Involved in neuronal guidance in CNS
51
Q

Integrins

A
  • Calcium independent
  • Involved in cell-cell and cell-matrix adhesions
  • Heterotypic binding
    • Interact with extracellular matrix molecules
      • Collagens
      • Laminin
      • Fibronectin
    • Interacts with actin and intermediate filaments
  • Important in cell behaviors like apoptosis and migration
52
Q

Tight Junctions

A

A.k.a occluding junctions or zonulae occludens

  • Forms continuous seals around cells in belt-like fashion
  • Rows of transmembrane proteins form sealing strands
  • Transmembrane:
    • occludins
    • claudins
  • Adaptor protein:
    • Scaffolding proteins
      • ZO-1, ZO-2, ZO-3
  • Filaments:
    • Actin
53
Q

Adhering Junction

Characteristics

A
  • Connect cells to one another or to ECM
  • Also connect cytoskeletal filaments to plasma membrane
  • All adhering junctions are composed of two categories of proteins:
    • Adaptor proteins
    • Cell adhesion molecule
  • Types:
    • Zonula adherens
    • Desmosome
    • Hemidesmosome
    • Focal contact/adhesion
54
Q

Adaptor Proteins

A

Intracellular achors that attach cytoskeletal filaments to cytoplasmic domain of CAMs.

Most form plaques on cytoplasmic face of membrane.

55
Q

Zonula Adherens

A
  • Found only in epithelia and only as part of junctional complex
  • Forms continuous belt around entire cell
  • Transmembrane CAMs:
    • E-cadherin
  • Adaptor proteins:
    • Vinculin
    • Catenin
    • Alpha-actinin
  • Filaments:
    • Actin
56
Q

Fascia Adherens

A

Similar to zonula adherens but only forms a large irregular patch.

Found in intercalated discs of cardiac muscle cells.

57
Q

Desmosome

A
  • Found in epithelia
    • Can be part of junctional complex or scattered elsewhere
  • Found as part of intercalated disks joining cardiac muscle cells
  • Transmembrane CAMs:
    • E-cadherin in epithelia
  • Adaptor proteins:
    • Desmoplankin
    • Plakoglobins
  • Filaments:
    • Keratin in epithelia
58
Q

Hemidesmosome

A
  • Anchors intermediate filaments of cytoskeleton to cell membrane
  • Anchors cells to the basal lamina of basement membrane
  • Transmembrane CAMs:
    • Integrins
    • Type XVII collagen (Bullous pemphigoid antigen 2 / BPAG2)
  • Adaptor proteins:
    • Plectin
    • Erbin
    • Dystonin (BPAG1)
  • Filaments:
    • Keratin
  • Basement membrane components:
    • Laminin
    • Type IV collagen
59
Q

Focal Contact/Adhesion

A
  • Cell-ECM junctions
  • Found in fibroblasts, some epithelial cells, and smooth muscle
  • More labile than hemidesmosomes
    • Important where contacts must be repeatedly broken and reformed
  • Transmembrane:
    • Integrins
  • Adaptor proteins:
    • Talin
    • Paxillin
    • Alpha actinin
    • Vinculin
  • Filaments:
    • Actin ⇒ stress fibers
  • Basement membrane:
    • Laminin
    • Fibronectin
60
Q

Gap Junctions

A
  • Found in epithelial cells, osteocytes, neurons, smooth/cardiac muscle cells
  • Allows communication & passage of ions/small molecules between cells
  • Connexins subunits form a connexon
  • Many connexons align to form gap junction
  • Can be in open or closed conformation
61
Q

Epithelial Tissue

A
  • Lines internal and external body surface
  • Makes up glands
  • Cells closely apposed
62
Q

Connective Tissue

A
  • Broad category including ordinary CT, blood, cartilage, bone, lymphoid, adipose
  • Binds tissues/organs
  • Provides support and protection
  • Medium for diffusion
  • Extensive ECM
    • many fibers embedded in ground substance
63
Q

Surface Ectoderm

Derivatives

A
  • Epidermis
  • Enamel
  • Internal ear
  • Corneal epithelium
  • Lens of eye
  • Anterior pituitary
64
Q

Neuroectoderm

Derivatives

A
  • CNS
  • PNS
  • adrenal medulla
  • melanocytes
  • mesenchyme of head
  • inner structures of teeth
65
Q

Mesoderm

Derivatives

A
  • CT
  • striated and smooth muscles
  • heart,
  • blood and lymphatic vessels
  • spleen
  • kidneys
  • gonads
  • mesothelium
  • adrenal cortex
66
Q

Endoderm

Derivatives

A
  • Epithelial lining of respiratory tract
  • urinary bladder
  • digestive tract and glands
  • thyroid
  • parathyroid
  • thymus
  • lining of ear
67
Q

Chorus-line effect

A

Nuclei of dividing epithelial cells move closer to the apical end.

68
Q

Simple Squamous

Locations

A
  • Lumen of blood vessels (endothelium)
  • Lining body cavities (mesothelium)
  • Covering epicardium of heart (mesothelium)
  • Forming outer wall of renal corpuscles (Bowman’s capsule)
69
Q

Simple cuboidal

Locations

A
  • Proximal and distal tubules of kidneys
  • Smaller ducts in some exocrine glands
70
Q

Simple Columnar

Locations

A
  • Lining lumen of stomach, intestines, and gall bladder
  • Lining lumen of larger ducts in some exocrine glands
    • Exocrine pancreas
71
Q

Minimally keratinized stratified squamous

Locations

A
  • Lining of lumen of esophagus and vagina
  • Parts of the oral cavity
    • Inner cheeks
72
Q

Max. keratinized stratified squamous

Location

A

Epidermis of skin

73
Q

Stratified Cuboidal

Locations

A

Ducts of sweat glands

74
Q

Stratified Columnar

Locations

A

Parts of very large ducts in some exocrine glands

Ex. submandibular gland

75
Q

Pseudostratified columnar

Locations

A
  • Parts of the respiratory tract
    • trachea
    • bronchi
  • Parts of the male reproductive tract
    • epididymis
    • vas deferens
76
Q

Transitional epithelium

Locations

A

Parts of the urinary system

Ureters

Urinary bladder

Proximal part of urethra

77
Q

Transport across epithelial sheet

A

Many transporting epithelia are simple cuboidal and simple columnar, few are stratified.

Ex. sweat gland ducts

78
Q

Epithelial Sensory Receptor Function

A

Taste buds composed of epithelial cells

Olfactory epithelium contains oder-detecting olfactory receptor cells.

79
Q

Basement Membrane

A
  • Basal lamina
    • Components made by epithelial cells
    • Divided into lamina lucida and lamina densa
      • Collagen type VI in lamina densa
    • Anchoring fibrils
  • Reticular lamina
    • Components made by CT cells
    • Reticular fibers

Anchoring fibrils (collagen type VII) attach basal lamina to reticular lamina by wrapping around bundles of reticular fibers (collagen type III).

80
Q

Layers of the Epidermis

A

Inferior to superior:

  1. Stratum Basale
    • single layer of cuboidal cells
    • rests on basal lamina
    • stems cells
  2. Stratum Spinosum
    • 5-10 layers of cells
    • transition from polygonal to flat as you move up
    • processess connected by desmosomes
  3. Stratum Granulosum
    • 3-5 layers
    • Elongated cells
    • Basophilic keratohyalin granules
    • Lamellar granules by EM
  4. Stratum Lucidum
    • Pale-staining
    • Only visible in thick skin
  5. Stratum corneum
    • 15-20 layers of non-nucleated squamous cells
    • filled with keratin
81
Q

Thick vs Thin

Skin

A

Based on epidermis thickness.

  • Think skin
    • all 5 layers
    • thick stratum corneum
    • hairless (glabrous)
    • only on palms and soles
  • Thin skin
    • no stratum lucidum
    • thinner stratum corneum
    • has hairs (vellus)
82
Q

Dermis

Layers

A
  • Papillary layer
    • just beneath epithelium in dermal papillae
    • loose CT
    • Interdigitats with epidermal pegs (ridges)
  • Reticular layer
    • deep to papillary
    • composed of dense irregular CT
83
Q

Epidermal-Dermal

Connections

A

Epidermis connected to dermis via basement membrane.

Dermal papillae fit into inter-papillary pegs of epidermis.

84
Q

Keratinocyte

A
  • Produces keratin
  • Stem cells in stratum basale
  • Differentiate as they move up
  • Basophillic due to free ribosomes
  • Apoptosis then desquamate
85
Q

Keratinization

Process

A
  • Keratin protein made in stratum basale and assemble into tonofilaments
  • In stratum spinosum, tonofilaments bundled into tonofibrils
    • Cytoplasm more eosinophilic
  • Near top of stratum spinosum, keratohyalin granules made.
    • Contain filaggrin and trichohyalin
    • Promote aggregation of tonofibrils
  • Granules have dispersed into cytoplasm by stratum lucidum.
  • Tonofibrils + keratohyalin granule proteins ⇒ soft keratin
  • Keratinocyte cornifies
    • nucleus and organelles break down
    • plasma membrane thickens
  • Cells desquamated from stratum corneum as part of “squares”
86
Q

Formation of Water Barrier

A

Via membrane-coating granules (MCGs) aka lamellar bodies

  • MCGs first made in stratum spinosum
    • Contains lipids and several enzymes
  • In upper stratum granulosum, MCGs fuse with plasma membrane
  • Contents secreted via exocytosis into intercellular spaces between stratum granulosum and stratum corneum
  • Several insoluble proteins form a layer called cell envelope on the inner surface of the plasma membrane which also contributes
    • Loricrin
    • Desmoplankin
    • Elfin
    • Envoplakin
    • Filaggrin
87
Q

Melanocytes

A
  • Located between keratinocytes of stratum basale
  • Pale staining in H&E
  • Derived from neural crest cells
  • Have long processes that extend between keratinocytes of stratum basale and spinosum
  • Produces melanin
88
Q

Melanin Synthesis

A
  • Made within melanosomes
  • As melanosomes mature, move to processes and pinch off ⇒ cytocrine secretion
  • Phagocytized by neighboring keratinocytes
    • Melanosomes and melanin content gradually degraded via autophagy
    • Keratinocytes get lighter as they move up
89
Q

Langerhans Cells

A
  • Stellate, pale staining cells with long processes
  • Found mainly in stratum spinosum
  • A type of dendritic cell involved in immune response
  • Possess membrane bound Birbeck granules
    • ping pong paddle shape
    • part of endosome system
90
Q

Merkel Cells

A
  • Epithelial derivatives
  • Function as touch receptors
  • Lies on basement membrane
  • Bound to keratinocytes by desmosomes
  • Have keratin filaments
  • Contain neurosecretory granules basally
  • Base of cell in contact with expanded nerve called Merkel Disc
    • Both form Merkel Corpuscle