Histology Flashcards
(150 cards)
1
Q
Define fixation
A
physical or chemical (most common) method of killing and preserving tissue while retaining characteristic features of shape and structure
2
Q
most common fixative for light microscopy
A
formalin
3
Q
size of sections needed for light microscopy
A
3-10 microns
4
Q
samples for light microscopy are embedded by
A
infiltration with paraffin wax
5
Q
a hypothetical “ideal fixative” would
A
- penetrate quickly
- render all parts of cell permanent
- allow use of all kinds of subsequent stains/tests
- cause no change by cell shrinkage
6
Q
how does formalin work
A
cross-links membrane proteins by covalent bonding
7
Q
ideal qualities of formalin
A
- penetrates quickly
- causes little distortion
- does not destroy cellular constituents
- can be followed by almost all stains
8
Q
disadvantages of formalin that can be helped by combining with another fixative
A
hardens tissues slowly, does not protect them from shrinkage during embedding/sectioning
9
Q
standard fixative for electron microscopy
A
osmium tetroxide (OsO4) ^often just called osmium
10
Q
ideal quality of osmium
A
preserves cell closer to living form than any other fixative
11
Q
disadvantages of osmium
A
penetrates poorly and cannot be followed by many stains
12
Q
what is stained black with osmium
A
fat and various lipid-containing materials (ie myelin sheaths)
13
Q
size of section needed for electron microscopy
A
.1 micron (30-100 times thinner than what can be used with light microscopy)
14
Q
samples for electron microscopy are embedded with
A
a plastic -> epon or araldite (epoxy resins)
15
Q
what are serial sections
A
multiple consecutive tissue sections prepared as slides
16
Q
Serial sections can help visualize 3D structure;
Different stains can be used on serial sections;
what other reason might serial sections be used?
A
they can increase the likelihood if finding an abnormality because pathologic changes can be patchy or focal
(serial sections increase sensitivity)
17
Q
what tool is used to create serial sections
A
microtome
18
Q
what is a a Giemsa/Wrights stain primarily used for?
A
peripheral blood smears
19
Q
what is a hematoxylin and eosin (H and E) stain used for?
A
it is the primary stain for tissues in pathology
20
Q
Masson’s Trichrome stain is often used for liver biopsies. What does this stain help visualize?
A
collagen/fibrosis
21
Q
What colors are seen in Masson’s trichrome stain?
A
- BLUE (GREEN) for collagen fibers
- RED for muscle fibers
- BLUE for nuclei (due to H and E first stain)
22
Q
PAS stain is important for detecting diabetic changes in the kidney. What does Periodic Acid Schiff (PAS) stain show
A
specific carbohydrates and carbohydrate compounds
23
Q
Immunohistochemistry (IHC) is a technique used with light microscopy that allows selective viewing of antigens (typically proteins) by using the principle of
A
specific antibody-antigen binding
24
Q
Because immunohistochemistry (IHC) allows us understand the distribution of specific cellular constituents, how can it be clinically helpful?
A
- narrowing differential diagnoses
- identifying tissue of origin in metastatic disease
- provide prognostic information in malignancies
25
Antigens in what location(s) can IHC bind
*anywhere
| cell membrane, cytoplasm, or nucleus
26
basic prep of tissues for exam
collect -> fix -> cut -> mount -> stain
27
Epithelial tissue can be derived from all three embryologic germ layers. Where might you find epithelial tissue derived from ectoderm?
epidermis
28
Epithelial tissue can be derived from all three embryologic germ layers. Where might you find epithelial tissue derived from mesoderm?
mesothelial cells
29
Epithelial tissue can be derived from all three embryologic germ layers. Where might you find epithelial tissue derived from endoderm?
lining of GI tract
30
2 main forms of epithelial tissue
* sheets the line the body surfaces (internal and external)
| * glands
31
Epithelial tissue has a lack of dedicated blood supply and needs to obtain nutrients/waste through
diffusion from underlying CT
32
All epithelial tissue is attached to
a basement membrane called basal lamina
33
epithelial cells have apical and basal surfaces, making them
structurally and functionally polar
34
where will you find simple squamous epithelium?
* body cavities (mesothelium)
* inner lining of vascular system (endothelium)
* lung alveoli
35
where will you find simple cuboidal epithelium?
* kidney tubules
* endocrine glands
* covering of ovary
36
where will you find simple columnar epithelium?
* inner lining of GI tract
| * Inner lining of Reproductive tract
37
There are 4 kinds of mesothelium, what are they found?
| hint: the 4th kind is found only in males
* pleural cavity
* pericardium
* peritoneum
* tunica vaginalis of testes
38
where will you find stratified squamous epithelium?
* oral cavity
* skin (epidermis)
* vagina
39
where will you find stratified cuboidal epithelium?
* ducts of glands
| * very rare: sweat glands and male urethra
40
where will you find stratified columnar epithelium?
| hint: it's very rare in the body
* conjunctiva
| * vas deferens
41
Mucosa and skin both have stratified squamous epithelium. What is the main differentiating detail between the 2?
skin has a superficial keratin layer (stratum corneum)
| and mucosa does not
42
where will you find pseudostratified epithelium?
* respiratory: lining nasal cavity, sinus, trachea, bronchi
* lining auditory tube and part of tympanic cavity
* lining of epididymis and ductus deferens
43
transitional epithelium or urothelium is found where?
* lining urinary tract from kidney to urethra
| * esp important in bladder
44
in what tissue type are tight junctions found?
epithelia
45
function of tight junctions
•barriers that regulate movement of water and solutes between epithelial cells
46
movement of solutes through tight junctions is heavily dependent on
size and charge
47
damage to tight junctions by trauma can cause
leakage and bleeding (edema)
48
main transmembrane proteins in tight junctions
occludin and claudin
49
gap (communicating) junctions allow for coordinated responses and activities of epithelium by
mediating intercellular (cell-to-cell or cell-to-tissue) communication by permitting passage of small molecules
50
transmembrane proteins involved and structure of gap junctions
connexins that organize into 6-unit connecons with a central hydrophilic channel
51
In what organ are gap junctions especially important?
the heart; allows coordinated electrical impulses: SA node -> AV node -> bundle of HIS
52
key characteristic of cilia
* motile structures
| * composed of microtubules
53
key characteristics of microvilli
* non-motile, but absorptive (increase SA)
| * composed of actin
54
all multicellular glands develops as
outgrowths of epithelium into underlying CT
55
multicellular exocrine glands can be distinguished by the presence of
a duct (stratified cuboidal)
56
exocrine glands, by definition, secrete where
onto a body surface or into a body cavity
57
what is a single cell exocrine gland
* goblet cell
| * no duct, but secretes onto a body surface or into a body cavity
58
endocrine glands secrete where
* no duct
| * product released to blood
59
all connective tissue is derived from what embryonic germ layer?
mesoderm/mesenchyme
60
what 3 main components can be found in all connective tissue (except blood/lymph)?
* fibers -> dense, acellular (not in blood/lymph)
* cells
* ground substance (ECM; not in blood/lymph)
61
what are the 2 main component of the ground substance of CT?
glycoproteins and proteoglycans
62
prominent cell type in CT proper
fibroblasts
63
prominent cell types in cartilage
chondroblasts and chondrocytes
64
prominent cell types in bone
* osteocytes
| * osteoblast/osteoclasts
65
prominent cell type in adipose tissue
adipocytes
66
prominent cell type in blood
* erythrocytes
* leukocytes
* thrombocytes
67
What are they main types of CT
* CT Proper: DRCT, DICT, LCT
| * Specialized: Cartilage, Bone, Adipose, Blood, reticular tissue
68
adipose tissue and blood are unique CT in that they lack
ground substance
69
```
function of fibroblasts (active cells)
when resting, they're called fibrocytes
```
* produce elastic and collagen fibers
| * important in wound healing
70
function of elastic and collagen fibers in CT proper
* medium for oxygen and nutrients to diffuse from capillaries to cells, and waste to go opposite direction
* resist stretching and tearing forces
71
in dense regular CT, collagen fibers are bundled
in a parallel fashion
72
where would you find dense regular CT
tendons and ligaments
73
specialized function of dense regular CT
great tensile strength that is resistant to pulling forces, especially in one direction (parallel to the fibers)
74
Why do damaged tendons and ligaments take so long to heal?
because dense regular CT has a very poor blood supply; capillaries are very few and far between
75
where would you find dense irregular CT
| hint: it resists pulling forces in multiple directions
mainly in the reticular (deep) layer of the dermis
76
chondrocytes can be found in lacunae within cartilage. What is their function?
produce elastic fibers
77
function of elastic fibers in cartilage
resist stretching and tearing forces in cartilage
78
function of osteoblasts
lay down bone
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function of osteoclasts
"eat" bone
80
balance of what cell types is important in keeping bone strong?
osteoclasts and osteoblasts
81
osteocytes are found within lacunae of bone. What is their function?
maintain nutrition to bone and ECM
82
key identifying histologic feature of osteoclasts
they are generally multinucleated
83
80% of total bone mass in adults is made up of cortical bone, which is the outer "hard" layer. What are identifying histologic features of cortical bone?
networks of haversian canals, which contain blood vessels
84
trabecular bone is the inner "spongy" or soft bone which is composed of intersecting trabeculae. What is found within the space between trabeculae?
bone marrow, where hematopoesis occurs
85
Adipocytes can mobilized energy sources in response to hormonal stimulation. what is a special function of adipocytes?
synthesis and storage of fat
86
what type of fibers will be found between adipocytes in adipose tissue
elastin
87
most of the volume of adipocytes is made up of lipids. What does adipose tissue look like histologically?
balloons with peripherally located nuclei that will only be visible for some
88
most fat is white adipose tissue. Where might you find brown adipose tissue?
newborns
89
blood/lymph is a unique type of CT in that it lacks
* both ground substance and fibers (collagen or elastic)
| * tho some say that plasma is the matrix of blood
90
reticular fibers can be thought of as "connective tissue within connective tissue."
what type of collagen is found in reticular fibers
type III
91
where would you find the fine, lace-like meshwork of CT known as reticular tissue?
lymph nodes and spleen
92
which types of muscle are striated
skeletal and cardiac
93
skeletal muscle is a highly organized system of contractile proteins that are formed by the fusion of individual cells during development, making them
multinucleated
94
unlike skeletal muscle, cardiac muscle cells are
mononuclear and branching
95
smooth muscle is made up of spindle-shaped cells that are connected to one another via
gap junctions
96
contrasted with cardiac and skeletal muscle, smooth muscle cells have ____ contractions and are ____ organized
slower; less
97
come, let's get sun burned
```
the layers of the skin from superficial to deep:
•stratum corneum
•stratum lucidum
•stratum granulosum
•stratum spinosum
•stratum basale
```
98
which layer of the epidermis is responsible for repair and regeneration?
stratum basale
99
which layer of epidermis contains melanocytes
stratum basale
100
what function do melanocytes have
pigment (melanin) producing
101
what function do langerhans cells have in the epidermis
antigen-presenting
102
what function do merkel cell have in epidermis
tactile
103
keratinocytes are the squamous epithelial cells of our epidermis. Where would you find dead keratinocytes
in the stratum corneum. this is the "keratinized" layer
104
other names for hypodermis
subcutaneous layer or subcutis
105
Since the epidermis is epithelium, and therefore avascular. The vascular dermis needs to support it with nutrients. What is another important function of dermis?
thermoregulation, which also has a lot to do with vascularization (vasoconstriction/dilation) as well as arrector pili muscles/hair follicles (goose bumps)
106
what are the cellular components of the dermis
•fibroblasts (mostly)
and immunologic cells:
•macrophages
•mast cells
•other leukocytes
107
non-cellular components of dermis
* collagen (type I and II)
* elastic fibers
* ground substance
108
papillary dermis is made up of what kind of tissue?
loose (areolar) CT
109
reticular dermis is made up of what kind of tissue?
dense irregular CT
110
most common kind(s) of skin cancer and cells involved
* squamous cell carcinoma (keratinocytes in stratum spinosum)
* basal cell carcinoma (basal cells=primitive keratinocytes in stratum basale)
111
melanoma is actually a less common type of skin cancer, but is often more deadly and more prone to metastatic processes. Where is this cancer found and what cells are involved
the melanocytes, which are located in stratum basale
112
another kind of skin cancer is called Merkel cell carcinoma, which involved the tactile merkel cells. where are they located?
stratum basale
113
friction blisters occur most commonly on the soles of feet. What layers of skin are involved and how does this happen?
•fluid build-up between epidermis and dermis due to issue with anchoring junctions (hemidesmosomes)
114
hypopigmentation (albinism) is a non-neoplastic condition of the skin. what is the problem in this condition?
congenital defect in melanin producing pathway (eg defect in tyrosinase)
115
depigmentation (vitiligo) is a non-neoplastic condition of the skin that is postulated to be an auto-immune disease. What occurs in this condition?
acquired condition with loss or decreased activity of melanocytes
116
what kind of tissue is found in the hypodermis/subcutis?
loose (areolar) CT
117
all luminal regions of the GI tract have certain structural features in common, which are
* lumen
* mucosa
* submucosa
* muscularis propria
* serosa/adventitia
118
mucosa of the GI tract can be broken down into
* epithelial lining
* lamina propria (loose CT)
* muscularis mucosa
119
submucosa of GI tract is made up of what kind of tissue
dense CT
120
serosa/adventitia is made up of what kind of tissue
loose CT
121
the muscularis propria is generally broken down into what 2 layers
inner circular
| outer longitudinal
122
what is located between the inner circular and outer longitudinal layers of muscularis propria
myenteric nerve plexus
123
there is are 2 nerve plexuses in the GI tract. the myenteric nerve plexus is located between the 2 layers of muscularis propria. What is the other plexus
submucosal plexus
124
what 2 parts of the GI tract are lined by squamous, not columnar epithelium?
esophagus and anus
125
what is the GE junction
the gastroesophageal junction is where you can see a transition between stratified squamous epithelium (esophagus) to simple columnar (stomach)
126
2 important secretions from gastric glands
HCL and pepsinogen
127
what's the main histologic difference between small and large intestine?
large intestine has crypts, but not villi, while small intestine has both
128
what does the appendix look like histologically?
resembles the colon, but has innumerable lymphoid aggregates with reactive germinal centers in the mucosa and submucosa
129
the pancreatic exocrine function is carried out by acinar cells, which produce 1.5 L of alkaline pancreatic juice per day and secrete them to the duodenum. What types of substances are made
proteases, amylases, lipases
130
the endocrine function of the pancreas is carried out by the islets of langerhan. what substances are made here?
insulin, glucagon, somatostatin
131
the main digestive function of the liver is to produce bile. What other functions do hepatocytes carry out
hint: think production and storage
* synthesis of plasma proteins
* conversion of amino acids to glucose
* production of urea
* storage of glucose
* storage of vitamin A
* storage of iron
132
what type of epithelium will you find lining body cavities (mesothelium)
simple squamous
133
what type of epithelium will you find in the inner lining of vascular system (endothelium)
simple squamous
134
what type of epithelium will you find in lung alveoli
simple squamous
135
What type of epithelium is found in kidney tubules
simple cuboidal
136
What type of epithelium is found in endocrine glands
simple cuboidal
137
What type of epithelium is found covering of ovary
simple cuboidal
138
What type of epithelium is found in the inner lining of GI tract
simple columnar
139
What type of epithelium is found in the Inner lining of Reproductive tract
simple columnar
140
What type of epithelium is found in the oral cavity
stratified squamous
141
What type of epithelium is found in skin (epidermis)
stratified squamous (keratinized)
142
What type of epithelium is found in the vagina
stratified squamous
143
What type of epithelium is found in ducts of glands
stratified cuboidal
144
What type of epithelium is found in sweat glands
stratified cuboidal
145
What type of epithelium is found in the male urethra
stratified cuboidal
146
What type of epithelium is found in conjunctiva
stratified columnar
147
What type of epithelium is found in the vas deferens
stratified columnar
148
What type of epithelium will you find lining nasal cavity, sinus, trachea, bronchi
pseudostratified
149
What type of epithelium will you find lining the auditory tube and part of tympanic cavity
pseudostratified
150
What type of epithelium will you find in the lining of epididymis and ductus deferens
pseudostratified
