MA1 - Intro to Microanatomy Flashcards

1
Q

What are the five types of tissue?

A

blood/lymphoid

muscle

nervous

epithelial

connecive

[mnemonic: Bloody Maries Cause Epithelial Necrosis]

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2
Q

What is the primary function/feature of blood/lymphoid tissue? (2)

A

transport of gases; immune function

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3
Q

What is the function of muscle tissue? (2)

A

generates contractile forces that drive internal motion of organ

drives movement of organism itself

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4
Q

What are the three types of muscle tissue?

A

skeletal muscle

smooth muscle

cardiac muscle

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5
Q

What is the function of nervous tissue?

A

provides rapid, long-range communication to and from cells/tissues

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6
Q

What are the two types of nervous tissue? (2)

A

CNS tissue (brain, spinal cord, eye)

PNS tissue (somatic and autonomic nervous systems)

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7
Q

What is epithelial tissue?

A

sheets of cells (epithelia) that cover internal and external surfaces

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8
Q

Epithelial tissue forms

A

secretory and ductal elements of glands

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9
Q

What is the function of connective tissue?

A

supports, insulates, separates, and protects other tissues

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10
Q

The epithelium that forms the innermost tissue layer of intestines is primarily composed of what kind of cells?

A

absorptive cells (enterocytes) + goblet cells

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11
Q

What is the function of enterocytes in the small intestine?

A

absorb nutrients

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12
Q

What is the function of enterocytes in the colon?

A

absorb water

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13
Q

What do goblet cells do?

A

produce mucus that coats and protects luminal surface

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14
Q

Lamina propria is made of what kind of tissue?

A

connective tissue

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15
Q

Describe the lamina propria. (2)

A

contains blood + lymphatic vessels that transport materials to and from epithelium

site of immune reactions

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16
Q

In which cellular structure do immune reactions occur?

A

lamina propria

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17
Q

List the order of tissue structures, from epithelium at the top to those below.

A

epithelium

lamina propria

muscularis mucosae

submucosa

muscularis propria

serosa

(mnemonic: ELMo can’t send SMSes)

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18
Q

What structures comprise the mucosa?

A

epithelium + lamina propria + muscularis mucosae

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19
Q

Describe the muscularis mucosae.

A

thin layer of smooth muscle

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20
Q

Describe the submucosa.

A

richer in collagen than lamina propria

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21
Q

The submucosa is responsible for providing support to which structures?

A

blood vessels

lymphatic vessels

PNS nerves/ganglia that innervate mucosa

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22
Q

Describe the composition of the muscularis propria.

A

inner circular layer perpendicular to intestinal axis

outer longitudinal layer parallel to intestinal axis

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23
Q

What is the significance of the space between the two layers of the muscularis propria?

A

ganglia of enteric nervous system reside in space between and control the musclaris propria

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24
Q

Describe the composition of the serosa.

A

squamous epithelium (mesothelium) that faces peritoneal cavity

thin layer of connective tissue b/w mesothelium and outer smooth muscle layer of the muscularis propria

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25
Q

What are mesothelial cells?

[Alt.] What is the mesothelium?

A

simple squamous epithelium that lines internal body cavities

lines the serosa

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26
Q

What is the adventitia?

A

outermost layer of many tubular structures, such as the GI tract

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27
Q

What is the composition of the adventitia? (3)

A

mostly composed of dense connective tissue

if smooth muscle is present it commonly runs parallel to the tube and serves a support role

lacks mesothelium

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28
Q

What are the steps in histological sample preparation?

A

sample acquisition

fixation

processing

sectioning

staining

(mnemonic: SFPSS)

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29
Q

What is the purpose of fixation?

A

to preserve tissue and tissue structure

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30
Q

How is fixation performed?

A

using chemical fixatives

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31
Q

What are the two types of chemical fixatives used in fixation?

A

crosslinking fixatives (formaldehyde)

oxidizing fixatives (osmium tetroxide)

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32
Q

What is the difference between immersion and perfusion in fixation?

A

immersion = sample soaked in fixative - preserves blood cells in vessels

perfusion = fixative introduced into sample through vasculature - blood cells lost

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33
Q

What is the purpose of processing in sample preparation?

A

replace water with a stiff matrix to facilitate sectioning

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34
Q

What are the two steps of processing in sample preparation?

A

dehydration

embedding

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35
Q

Describe the dehydration step of processing in sample preparation.

A

ethanol followed by clearing agent (xylene) to facilitate infiltration by embedding agents

36
Q

Describe the embedding step of processing in sample preparation. (2)

A

generates a “block” in which tissue is suspended in solid matrix

waxes such as paraffin or acrylic resins such as methacrylate are used

37
Q

What happens in sectioning of sample preparation?

A

block is cut with a microtome = expensive meat slicer

38
Q

What are the types of stains? (5)

A

ionic stains

redox stains

fluorescent dyes

heavy metals (EM)

immunostains (IHC, IF, IG)

39
Q

Basic dyes bind to what charges?

A

basic dyes (positive charges) bind to negative charges

40
Q

Acidic dyes bind to what charges?

A

acidic dyes (negative charges) bind to positive charges

41
Q

What is the most commonly used stain in histology?

A

hematoxylin & eosin (H&E)

42
Q

Describe the components of the H&E dye.

A

hematoxylin = blue basic dye

eosin = red acidic dye

43
Q

What happens when H&E staining is carried out under acidic conditions?

A

hematoxylin binds to macromolecules rich in phosphates (DNA/RNA → thus stains nuclei/ribosomes) and sulfates (proteoglycans)

eosion binds to proteins (which are positively charged), staining them red (therefore stains collagen, actinomyosin, etc.)

44
Q

Distinguish between the terms basophilic and eosinophilic.

A

basophilic = stained with hematoxylin → negatively charged area → DNA/RNA/nuclei/ribosomes

eosinophilic = stained with eosin → positively charged area → protein/collagen/actinomyosin

45
Q

Compare H&E and toluidine blue staining.

A

Toluidine blue staining has superior contrast

46
Q

Describe the outcome of toluidine blue staining.

A

stains nucleic acids and other negatively-charged species blue

stains glycosaminoglycan (i.e. secretory granules of mast cells) reddish-purple

47
Q

Toluidine blue is commonly used to visualize what specific structure?

A

mast cells

48
Q

What is the function of Masson’s trichrome and how does it stain?

A

used to identify areas of fibrosis

protein-rich areas stained red

collagen stained blue

nuclei stained black

49
Q

When is Gomori trichrome used?

A

used to stain skeletal muscle

50
Q

How does Gomori trichrome stain?

A

myofilaments of muscle fibers = greenish blue

nuclei = reddish-purple

collagen = green

compacted membranes (i.e. cristae of mitochondria) = red

51
Q

What stain is used to identify mitochondrial myopathies?

A

Gomori trichrome

52
Q

Verhoeff and Gallego stains are used to visualize

A

elastic fibers

53
Q

Describe how Verhoeff and Gallego stains visualize fibers.

A

Verhoeff stains = gives elastic fibers black color but doesn’t stain other structures well

Gallego stains = gives elastic fibers reddish color but stains fibrillar collagens yellow or green

54
Q

What are the two primary redox stains?

A

Periodic Acid-Schiff (PAS)

Silver reticulin

55
Q

Describe the properties of the PAS stain.

A

reacts with/stains areas rich with polysaccharides

56
Q

The PAS stain is commonly used to target which cells?

A

mucus of goblet cells

glycocalyx of enterocytes

external laminae of muscle

basement membrane of epithelia

57
Q

The PAS stain is used as a diagnostic probe for which kinds of infections?

A

yeast and fungal infections (since their cell walls have lots of polysaccharides)

58
Q

Describe the properties of the silver reticulin stain.

A

redox reaction in which silver ions are reduced to metallic silver by macromolecules

59
Q

Describe how silver reticulin stains.

A

stained appears appear black

60
Q

Silver reticulin is commonly used to visualize

A

reticular fibers (type III collagen)

61
Q

Describe how fluorescent dyes are used to visualize structures.

A

fluorescent dyes fluoresce when excited by specific wavelengths of light

62
Q

Describe how heavy metals (EM stains) ar used to visualize structures.

A

heavy metals/EM stains bind to structures and scatter electrons in an electron beam

63
Q

Describe the role of primary and secondary antibodies in immunostains.

A

primary antibodies = bind to antigen of interest in the tissue

secondary antibodies = conjugated with enzyme/fluorophore/heavy metal and detect the primary antibody (actually performs the staining)

64
Q

Describe immunohistochemistry.

A

uses enzyme-conjugated secondary antibodies (most commonly, horseradish peroxidase)

65
Q

How does horseradish peroxidase stain?

A

stains brown where the primary antibody is found

66
Q

Immunohistochemistry is best used for the visualization of

A

cells, but not useful for visualizing subcellular structures

67
Q

Describe immunofluorescence.

A

uses fluorophore-conjugated secondary antibodies

68
Q

Immunofluorescence is useful for visualizing

A

subcellular structures

69
Q

Describe immunogold.

A

uses colloidal gold-conjugated secondary antibodies

70
Q

Immunogold staining is typically combined with what other staining method?

A

combined with heavy metal stains

71
Q

Which method is best for visualizing subcellular locations?

A

immunogold

72
Q

What are the two types of light microscopes?

A

transmitted light microscope

fluorescence microscope

73
Q

What are the two types of electron microscopes?

A

transmission electron microscope

scanning electron microscope

74
Q

Describe the properties of transmitted light microscopes.

A

light is co-linear w/ objective

75
Q

Describe the properties of fluorescence microscopes.

A

illuminating light not co-linear w/ objective

stains excited by incident light generate photos (i.e. they fluoresce)

greater specificity than transmitted light microscopy

76
Q

Which microscopy technique is most commonly used in diagnostic pathology?

A

transmitted light microscope

77
Q

Describe the properties of transmission electron microscopes. (3)

A

TEM generates electron beam that focuses on and passes through sample

beam spread from sample generates magnified image

atoms in sample deflect electrons as function of size of electron shells

78
Q

How do heavy metals appear in TEM?

A

heavy metals have large electron shells, so they appear dark on TEM images

79
Q

Describe the properties of scanning electron microscopes.

A

SEM uses metal (gold/palladium) plated whole mount samples

electron beam reflects off sample and is imaged at 90° to the beam

rotation of sample allows for generation of 3D image of sample surface

80
Q

Define scale.

A

fold difference in size

81
Q

Define magnification. (2)

A

ratio of apparent size to true size

is a function of the lens used

82
Q

Define resolution.

A

limiting distance at which two discrete objects can be visually distinguished

83
Q

What factors limit resolution?

A

resolution limited by wavelength of incident radiation

84
Q

Write out the formula to calculate resolution. Identify the terms.

A

d = resolution

lambda = wavelength

NA = numerical aperture

85
Q

What are the resolution limits for visible light and EM?

A

visible light = 0.2 um

EM = 1 nm