Epithelium and Glands Flashcards
(118 cards)
1
Q
How many different types of cells are there?
A
223
2
Q
Characteristics of epithelia
A
Highly cellular, lack intercellular material, covers and lines all body surfaces, forms the gland tissues, can be very regenerative, have surface modifications that facilitate functional roles, all have basement membrane, no direct blood supply
3
Q
Only few epithelial cells have a blood supply. T/F
A
False, epithelia do not have a direct blood supply
4
Q
All epithelia are associated with a basement membrane. T/F
A
True
5
Q
Tissue
A
A collection of cells and cell products having one or more common functions
6
Q
The difference between the basal and reticular lamina can be seen with a light microscope. T/F
A
False, the difference can be seen with an EM.
7
Q
Common characteristics of epithelia
A
Highly cellular Tightly adherent Avascular Highly regenerative Highly polarized Basement membrane Nuclei conform to cell shape Derived from all germ layers
8
Q
What germ layer is the epithelia derived from?
A
All germ layers
9
Q
Four ways epithelial cells vary
A
Shape
Number of layers
Intracellular structure
Mode of attachment
10
Q
Functions of epithelia (8)
A
Protection Transportation Secretion Excretion Absorption Lubrication Sensory reception Reproduction
11
Q
The classification of tissue as epithelial is based on what?
A
Microscopic structure
Location
Function (modifications)
Pathological behavior
12
Q
Epithelium is classified using what three characteristics?
A
Shape
Number of cellular layers
Surface modifications
13
Q
Simple epithelia
A
Single layer of cells, height varies
14
Q
Simple squamous epithelia structure
A
flat, thin cytoplasm, flattened nucleus
15
Q
Simple squamous epithelia function
A
Passive function role, permeable
16
Q
Simple squamous epithelia location
A
Anywhere exchanges/permeability is needed
17
Q
Endothelium
A
Simple squamous epithelium lining blood, lymphatic vessels, and heart
18
Q
Mesothelium
A
Simple squamous epithelium lining the body cavities (pericardial, pleural, peritoneal)
19
Q
Simple cuboidal epithelia structure
A
Square, nuclei round and central
20
Q
Simple cuboidal epithelia function
A
Active transport, synthesis of secretory products (increased cell volume supports more metabolic activities
21
Q
Simple columnar epithelia structure
A
Tall, oval nuclei located near basement membrane
22
Q
Simple columnar epithelia function
A
Protection, absorption, secretion
Contain goblet cells
23
Q
Simple columnar epithelia tend to be located on surfaces of curvature rather than flat. T/F
A
False.
Ex: found in inner surface of stomach rather than in secretory glands
24
Q
Goblet cells
A
Unicellular glands that occur in columnar epithelia
25
What staining method is effective for the basal lamina?
PAS staining, since the basal lamina is made of collagen, which is a glycoprotein, and proteoglycans
26
Pseudostratified columnar epithelia structure
All cells rest on basement membrane, but not all cells reach free surface, nuclei at different levels, usually has surface modifications
27
Respiratory epithelium
Ciliated pseudostratified columnar epithelium with goblet cells in upper respiratory tract
28
Pseudostratified columnar epithelia location
Upper respiratory tract
| Male reproductive system
29
What is the characteristic location of pseudostratified columnar epithelia?
Respiratory epithelium in upper respiratory tract
30
Stratified epithelia
At least two layers of cells, has basal stem cell population for regeneration
31
Stratified squamous epithelia location
Externally exposed surfaces subject to abrasion: skin, mouth, esophagus, vagina
32
Stratified squamous epithelia function
Protection against mechanical abrasion, desiccation, invasion
33
Stratified squamous epithelia structure
Top layer simple squamous
| Cornified skin cells have dead cell layers
34
Stratified squamous epithelia are referred to as keratinized and non-keratinized based on presence of dead cell layer. T/F
False, all epithelia have small amounts of keratin, so are referred to as cornified and non-cornified
35
Stratified cuboidal epithelia location
Luminal surfaces of large ducts of various glands (sweat, pancreas, parotid)
Uncommon
36
Stratified columnar epithelia function
Protection of large ducts
37
Stratified columnar epithelia location
Lines large ducts at transition zones (duct goes small to large), pancreas, parotid gland
Rare
38
Transitional epithelia function
Can be distended/stretched, relatively impermeable
39
Transition epithelia location
Uroepithelium
| Found exclusively in bladder, ureter, renal pelvis
40
Transitional epithelia structure
Scalloped/domed on top
| Binucleated cells
41
Epithelia are highly polarized. T/F
True
| Polarity reflects epithelial function
42
The modifications of the apical surface of epithelial cells have what three functions?
```
Protection
-Cornified layer
-Glycocalyx
Absorption
-Microvilli
-Stereocilia
Locomotion
-Cilia
-Flagella
```
43
Microvilli
- Have actin mf cores
- Anchored to intermediate filaments of the terminal web (anchored to ZA)
- Motile activity via actin-myosin interactions
- Increase surface area (glycocalyx)
44
The microvilli borders of the kidney tubules and intestines are called?
Brush border - kidney tubules
| Striated border - intestine (highly developed)
45
Stereocilia structure
Long, branched, flexible, clumped like a paintbrush
| Ezrin anchors actin filaments to tip, not villin
46
___ anchors actin microfilament cores to the tip in microvilli, while ___ does that in stereocilia.
Villin, ezrin
47
Ezrin anchors the actin cores to the tip in ___, which is done by villin in ___.
Stereocilia, microvilli
48
Stereocilia location
Found in the inner ear and epididymis
49
Cilia
Made of microtubules anchored to basal body (MTOC)
| Motile like spinning lasso
50
Cilia function and location
Found in tracheal cells, transport fluid across epithelia
| Without internal pair in axoneme, they act as mechanoreceptors
51
Cilia structure
Axoneme
9+2 arrangement, 9 microtubule pairs around 2 single microtubules
Dynein (using ATP hydrolysis) motor slides MT pairs past one another, bends cilia
Without internal pair, they act as mechanoreceptors
52
Where do cilia arise from?
The basal body (9+0) as a template, which acts as the MTOC
53
Where do the basal body come from?
Centrioles give rise to precentrioles, which migrate to cell surface an form basal bodies
54
What is the structure of the basal bodies?
9+0 triplets of microtubules
55
What is the function of the 9+0 monocilia?
Mechanoreceptors to determine axis
56
How does ciliary motility occur?
The dynein (using ATP hydrolysis) motor slides MT pairs past one another, bends cilia
57
What are the 3 types of lateral membrane modifications?
Barrier seals, mechanical anchors, and communicating junctions
58
Cilia can synchronize with the use of ___ in the lateral membrane.
Gap junctions
59
The ___ can act as an intercellular glue to reinforce adhesion of adjacent cells.
Glycocalyx
60
The membranes of adjacent cells can ___ to increase adhesion with help from the glycocalyx.
Interdigitate
61
Apical Junctional Complex (AJC)
Composed of zonula occludens, zonula adherens, and macula adherens
Regulates cell-cell adhesion, paracellular permeability and cell polarity
AKA terminal bar, looks like dark line on top of epithelial cells
62
Zonula occludens
Tight junction where membranes fuse partially, create ridges (more ridges means more closure, represent integral proteins)
Forms main paracellular diffusion barrier, act as gates or fence
63
The ridges of the zonula occludens in EM represent ___.
Integral proteins
64
What are the 2 functions of the zonula occludens?
Gate - paracellular pathway
| Fence - membrane compartmentalization
65
The zonula occludents prevents ___.
Intecellular passage
66
Zonula occludens proteins
Occludins - form tight seal, maintain barrier
Claudins - Allow for specific paracellular passage of certain substances
JAM (Junction adhesion molecules) - Link actin cytoskeleton of one cell to another cell
67
The permeability of the zonula occudens cannot be regulated. T/F
False, BBB can be permeated with drugs
68
Zonula adherens
Links the actin cytoskeleton between cells, provides lateral adhesion
69
The zonula adherens provides ___ adhesion by linking ___.
Lateral, actin cytoskeleton of adjacent cells
70
Zonula adherens proteins
Cadherins linked to microfilaments (actin) of cells bind to calcium between cells
71
Since ___ are composed of actin, they can join the actin web and link to ___.
Microvilli, zonula adherens
72
Macula adherens (desmosomes)
Link to IFs via transmembrane glycoproteins to plasma membrane
73
Which is the strongest of the lateral membrane modifications? Why?
Macula adherens, link to intermediate filaments
74
Which lateral membrane modification acts as barrier seals?
Zonula occludens
75
Desmosome structure
Cadherins - extracellular ligands link cells
| Intermediate filaments linked via proteins to plasma membrane
76
Desmosome function
Regulate morphogenetic development, cell differentiation, and wound regeneration
77
Hemidesmosome
Adhesion to basal lamina, link IFs to ECM
78
Hemidesmosome structure
Integrins - extracellular ligands
79
Hemidesmosomes use ___ as extracellular ligands, while desmosomes use ___.
Integrins, cadherins
80
Gap junction structure
6 connexon subunits pairs inserted into plasma membrane
81
Gap junctions cannot be regulated. T/F
False, they are active channels that can be opened and closed as needed (calcium, pH)
82
Basal infoldings
Where basal membrane encapsulated part of mitochondria, allowing for more surface area for pumps
Found in ducts and salivary glands
83
Where are basal infoldings found?
Ducts and salivary glands where fluid is actively being transported
84
What are the 2 layers of the basement membrane?
Basal lamina (lamina densa) and reticular lamina
85
Basal lamina structure
Lots of collagen, granules, and proteoglycans, hydrated
86
Reticular lamina
Made of type III collagen reticular fibers
87
The ___ is derived from epithelia and the ___ is derived from CT.
Basal lamina, reticular lamina
88
The ___ of the basement membrane is visible via light microscopy,
Reticular lamina
89
What are the two types of anchoring junctions?
Hemidesmosomes and focal adhesions
90
Focal adhesions
Bind microfilaments (actin) to the ECM of the basal lamina
91
___ use actin to anchor cells to the basal lamina, while ___ uses IFs.
Focal adhesions
| Hemidesmosomes
92
Functions of the basement membrane
Actively transports to underlying blood vessels and epithelium , selects what can pass through membrane, highway for cell migration
93
What 2 cell types are glands composed of?
Parenchyma - functional secretory cells of epithelial origin (active)
Stroma - supporting cells, of CT origin
94
___ cells of glands are derived from CT while ___ cells are derived from epithelia.
Stromal, parenchymal
95
How are exocrine glands developed?
Invagination of epithelium (downgrowth) that stays in contact with epithelium
96
How are endocrine glands developed?
Invaginations of epithelium that separate away from epithelium and become vascular
97
Endocrine glands
Release their products into blood via CT
98
Exocrine glands
Release products via ducts onto a surface
99
Goblet cells are considered glands of their own. T/F
True
100
Goblet cell
Unicellular glands that are polarized with secretory product towards lumen side of cell
101
How are exocrine ducts classified?
Ducts
Simple (unbranched) vs. compound (branched)
Secretory unit
Tubular, acinous (alveolar), or compound (both)
Secretions
Serous, mucous, mixed
102
Serous exocrine glands
Lots of proteins (enzymes) secreted, zymogen granules, round nuclei, watery
103
Mucous exocrine glands
Squished nuclei, glycoproteins, mucinogen granules are lost when fixed, so look vacuolated, lubricating for lumen of glands
104
___ glands have round nuclei while ___ exocrine glands have flat nuclei.
Serous, mucous
105
Serous exocrine glands have ___ as a definitive feature, while mucous glands have ___.
Zymogen granules
| Vacuoles
106
Where are mixed seromucous glands found?
Pancreas, salivary glands, trachea
107
Merocrine secretion
Exocytosis
108
Most glands use what type of secretion?
Merocrine
109
Holocrine secretion
Membrane breaks, cell dies
110
What type of glands are holocrine?
Sebaceous
111
Apocrine secretion
Membrane pinches off
112
What type of glands are apocrine?
Mammary glands (release lipids that need to be encapsulated)
113
What are the 3 structures of endocrine glands?
Clumps, cords, follicles
114
What types of tissues have static populations?
Neurons, muscle
115
What type of tissues have expanding populations?
Liver, kidney
116
What type of tissues have renewing cell populations?
Blood, skin, gut
117
Where is the mitotic activity of cells seen?
Basement membrane
118
Order these tissues based on epithelial cell lifespan: small intestine, trachea, bladder, skin
Small intestine < skin < trachea < bladder
