Epithelium Flashcards
(110 cards)
1
Q
what are parenchyma?
A
includes cells responsible for the tissue’s function
2
Q
what are stroma?
A
supporting tissue (usually connective tissue)
3
Q
function of epithelium?
A
line body surfaces and cavities, glandular secretions
4
Q
what are the “stromal cells” of the nervous tissue?
A
glial
5
Q
what do nervous cells look like?
A
intertwining, elongated processes
6
Q
what do epithelium cells look like
A
aggregated polyhedral cells
7
Q
muscle cells look like
A
elongated contractile cells
8
Q
amount of stroma cells from least to most in the 4 tissue types?
A
nervous, epithelium, muscle, connective
9
Q
what structures arise from the ectoderm?
A
- epidermis of skin and its derivatives (sweat glands, hair follicles)
- epithelial lining of mouth and anus
- cornea and lens of eye
- nervous system
- sensory receptors in epidermis
- adrenal medulla
- tooth enamel
- epithelium of pineal and pituitary glands
10
Q
what germ layer does the epidermis and its derivatives derive from?
A
ectoderm
11
Q
what germ layer does the epithelial lining of mouth and anus derive from?
A
ectoderm
12
Q
what germ layer does the cornea and lens of eye derive from?
A
ectoderm
13
Q
what germ layer does the nervous system derive from?
A
ectoderm
14
Q
what germ layer does the sensory receptors in the epidermis derive from?
A
ectoderm
15
Q
what germ layer does the adrenal medulla derive from?
A
ectoderm
16
Q
what germ layer does the tooth enamel derive from?
A
ectoderm
17
Q
what germ layer goes the epithelium of pineal and pituitary glands derive from?
A
ectoderm
18
Q
what structures arise from the mesoderm?
A
notochord skeletal system muscular system muscle layer of stomach and intestine excretory system circulatory and lymphatic systems reproductive system dermis of skin lining of body cavity adrenal cortex
19
Q
where does the notochord arise from?
A
mesoderm
20
Q
where does the skeletal and muscular system arise from?
A
mesoderm
21
Q
where does the excretory system arise from?
A
mesoderm
22
Q
where do the circulatory and lymphatic systems derive from?
A
mesoderm
23
Q
where does the reproductive system derive from
A
mesoderm
24
Q
where does the dermis of the skin arise from?
A
mesoderm
25
where does the lining of body cavity rise from?
mesoderm
26
where does the adrenal cortex arise from
mesoderm
27
what structures arise from the endoderm
```
epithelial lining of digestive tract
epithelial lining of respiratory system
lining of urethra, urinary bladder and reproductive system
liver
pancreas
thymus
thyroid and parathyroid glandcs
```
28
where does the lining of the urethra, urinary bladder and reproductive system arise from?
endoderm
29
where does the liver arise from
endoderm
30
where does the pancreas arise from
endoderm
31
where does the thymus arise form
endoderm
32
where do the thyroid and parathyroid glands arise from
endoderm
33
where does the epithelial lining of the respiratory system and digestive system arise from?
endoderm
34
what are the 4 major tissue types?
nervous
connective
epithelial
muscle
35
how are epithelial cells classified?
cell shape and number of layers
36
what membrane do epithelial cells form?
basement membrane
37
what cells form the basement membrane?
epithelial cells
38
where are apical and basal?
side facing lumen/space and side attaching to other tissue type
39
functions of the epithelial cells?
covering lining protecting
secretion
absorption
contractility
have to be tightly packed
40
what are squamous cells?
flattened, hexagonal-ish, many sides
41
what are cuboidal cells?
look like square, from top may look hexagonal
42
what are columnar cells?
tall, rectangular
43
what are stratified cells?
many layered cells
44
what are simple cells?
few or one layer
45
where is the basal surface, characterize
side facing underlying connective tissue, adhesion molecules and cell junctions
46
where is the apical surface
side facing a cavity or lumen, microvilli, cilia
47
where is the lateral surface
sides in contact with adjacent side, cell junctions
48
what is the basement membrane?
thin layer of specialized extracellular material between basal surface of epithelial cells and the underlying connective tissue, includes the bottom of epithelial cells and hemidesmosomes, the basal lamina, and the reticular lamina
49
what is the basal lamina?
membrane within the basement membrane that is made up of the lamina lucida and lamina densa, secreted from the epithelial cells
50
compounds in the basal lamina?
type IV collagen, laminin, entactin (nidogen), proteoglycans/GAGs (perlecan, GAGs)
51
what component of the basement membrane forms a patterned meshwork?
collagen
52
functions of the basement membrane?
1. structural attachment site for epithelial cells
2. semipermeable barrier for filtration of fluid and substances in underlying tissues/capillaries
3. have an influence on cell proliferation, differentiation, 4. msignal transduction, cell metabolism
5. pathway for cell migration
6. helps est. cell polarity
53
what stain is best for visualization of the basement membrane?
PAS-stain due to the presence of GAGs
54
functions of cell junctions?
1. forms seals
2. sites of adhesion (cadherin, desmosome, hemides)
3. channels for communication (gap jct)
55
what is the zonula occludens?
a tight junction involving the transmembrane protein claudin that forms a band completely encircling each cell and closes off the space between cells, forms a seal to prevent flow between cells, and prevents integral membrane proteins on the apical surface to be transferred to the basolateral surface and vice versa
56
types of anchoring junctions?
adherens (cadherins and actin, orderly "belt through belt loops intracellularly) toward the apical side, desmosomes (keratin and cadherin, jumble of intracellular filaments) toward middle, hemidesmosomes (integrins and basal lamina at basal end)
57
what are adherens junctions composed of? (zona adherens)
cadherins, actin, orderly belt through belt loops intracellularly, apical side
require Ca
directly below tight junctions, are continuous
58
what are desmosomes composed of?
keratin and cadherin, jumble of intracellular filaments toward middle (dense plaque)
disk shaped
59
what are hemidesmosomes composed of?
integrins and basal lamina, at basal side
| bind laminin and type IV collagen in basal lamina, anchored by keratin
60
what are gap junctions?
connexin forms connexon with hydrophilic core in the center, allows rapid exchange of molecules between adjacent cells
61
what is macula adherens?
spot desmosome, anchorage junction has spotlike distribution and is associated with intermediate filaments
62
what is zona adherens?
belt desmosome, anchorage junction, has beltlike distribution and is associated with actin
63
what do tight junctions do?
define cell polarity, control passage of substances between adjacent cells, have beltlike distribution like a ribbon internally bracing the cell, associated with actin
64
what are hemidesmosomes?
link basal domain of the cell to the basal lamina intermediate filaments via a plaque
65
what are microvili?
extensions of the plasma membrane that are made up of actin, fimbrin and myosin to increase surface area for absorption, covered by glycocalyx to make things stick, terminal web of actin at the base
66
what is the brush border?
combination of microvilli and glycocalyx in intestinal epithelium
67
what do microvilli look like in light microscopy?
tightly packed, almost solid looking, flat top/crew up, straight across, can sometimes see dense terminal web along apical boundary
68
where are stereocilia found, how are they different?
epididymis and vas deferens, also ears, longer and branched, core of actin filaments, not a consistent layer of actin
69
what is at the base of cilia?
basal body, 9+2 arrangement of microtubules
70
compare cilia and microvili
cilia are longer and more sparse than microvilli (individual cilia more easily discernable)
DARK LINE of basal bodies along apical surface of ciliated cells appears similar to terminal web of microvilli
71
where do stereocilia attach?
terminal web
72
how are stratified epithelia named?
according to the shapes on the surface layer cells
73
example of simple squamous epithelium/
air sacs of lung
74
example of pseudostratified ciliated columnar
respiratory tract
75
example of simple cuboidal
kidney tubule
76
example of simple columnar
intestine
77
example of stratified squamous
esophagus
78
describe shape, location and function of simple squamous epithelium?
- thin, flat cells with thin flat nuclei
- are in lining blood vessels as endothelium, air sacs (alveoli), and body cavities (mesothelium)
- allow for rapid exchange or diffusion
79
describe shape, location, and function of simple cuboidal epithelium
- as tall as they are wide with ROUND, centered nuclei
- in renal tubules (collecting tubule), thyroid glands, in a lot of things with a duct
- for absorption and secretion
80
describe shape, location, and function of simple columnar epithelium?
- taller than they are wide with round OR oval nuclei that are located basally or centrally
- in renal collecting ducts, oviduct/fallopian tube, lining of the gall bladder, intestinal mucosa
- specializes in absorption, often have microvili or cilia on apical surface and interspersed with secretory cells (goblet)
81
how to ID goblet cells
dilated apical cytoplasm containing light stained mucous material (which is secreted and coats epithelial surface)
82
describe stratified epithelium
cells layered for extra protection.
| found in skin, esophagus, cornea, excretory ducts, and more
83
explain keratinized cells
stratified squamous epithelium that are "dry" to prevent loss of moisture, are usually in the superficial epithelium of the skin and lack nuclei, look ropy and spacy
84
explain nonkeratinized cells
stratified squamous epithelium that are "wet" mucous membranes, like in the esophagus
85
explain the process of basal cell differentiation
basal cells undergo regular rounds of mitosis, pushing new cells up as they differentiate and flatten (keratinized cells lose their nuclei)
86
describe stratified cuboidal epithelium
NOT COMMON, exist mostly in glandular ducts, and even then are only a double layer of cuboidal cells
-are found in sweat ducts and esophageal mucous glands
87
describe stratified columnar epithelium
NOT COMMON, found in male urethra and palpebral conjunctiva (inner eyelid)
88
describe transitional epithelium shape, location, and function
- dome shaped superficial cells with aggregated protein plaques at apical surface for protection (from hypertonic urine), also have basal cells that are columnar or cuboidal that attach to basal lamina and don't reach lumen
- in bladder, ureters, urethra, prostate (called uroepithelium)
- can change shape to allow for stretching and distension, only 2-3 layers seen (shallow) when distended and many layers seen when contracted (empty)
89
describe pseudostratified epithelium shape, location, function
- APPEARS to be layered due to crowded arrangement of cells, but each cell's basal end contacts the basement membrane, so it is simple
- also have basal cells that don't reach the lumen
- respiratory tract, trachea
- commonly associated with goblet cells and cilia
90
what is an acinus?
rounded or spherical secretory portion of a gland
91
what are secretory cells?
epithelial cells in a gland
92
what is a duct?
conducting portion of gland where excretions exit
93
difference between simple and compound exocrine glands?
in simple glands, the main duct is unbranched but the secretory portions may be branched
in compound glands, the main ducts branch to serve multiple secretory units
94
what is a merocrine exocrine gland and an example
secretion of protein products via exocytosis of secretory granules, ex. salivary gland
95
what is a holocrine exocrine gland and an example
secretion is released by total disintegration of the cell, ex. sebaceous gland
96
what is a apocrine exocrine gland and an example
secretion involves loss of apical portion of the cell, usually containing one or more lipid droplets, ex. mammary gland
97
mechanism of merocrine secretion
secretory vesicle approaches apical domain, vesicular membrane fuses with plasma membrane and releases its components into the extracellular space, fused plasma membrane can be taken back into the cell by endocytosis and recycled
98
mechanism of apocrine secretion
some of apical cytoplasm is pinched off with the contained secretions, will see the pinched off portions on a slide
99
what is special about the mammary gland?
secretes milk lipids via apocrine secretion and milk protein casein by merocrine secretion
100
mechanism of holocrine secretion
the cell produces and accumulates a secretory product in the cytoplasm such as sebum (sebaceous glands), and then disintegrates to release the secretory material
101
what is special about merocrine glands?
they can be serous glands and mucous glands
102
describe serous merocrine glands
apical ends are eosinophilic due to abundant secretory vesicles (filled with serous/liquid/watery secretion)
basal ends are basophilic due to displacement of nucleus and abundant RER
103
describe mucous merocrine glands
apical region filled with pale staining mucin (mucous/thick/viscous/secretion of glycoproteins) secretory granules
basal region contains flattened nucleus, RER, and well developed golgi
are LARGER than serous cells
104
describe mucous cells
flattened basal nuclei, clear spongy appearing cytoplasm
105
describe serous cells
round basal nuclei, apical eosinophilic cytoplasm with reddish secretory granules, may have demilune (small half moon shape formed by serous cells that empty their product into interstices between mucous cells
106
where is regeneration and replacement most pronounced in epithelium?
exposed body surfaces, holocrine glands, intestinal tract and female reproductive tract
107
what occurs with chemotherapeutic agents and epithelial cells?
epithelium is an innocent target, so that is why side effects like nausea, vomiting, hair loss, and anemia occur (due to death of the epithelia)
108
what is adenoma
benign epithelial growth (glandular)
109
what is carcinoma
malignant tumor arising from surface epithelium
110
what is adenocarcinoma
malignant tumor derived from glandular epithelium, and it is the most common type of tumor in adults over 45
