Histology > Epithelium, Glands, and Specialization > Flashcards

Epithelium, Glands, and Specialization Flashcards

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1
Q

Type of EPITHELIA

A

SIMPLE

STRATIFIED

PSEUDOSTRATIFIED

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2
Q

Types of SIMPLE EPITHELIA

A

Squamous

Cuboidal

Columnar

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3
Q

Types of STRATIFIED EPITHELIA

A

Squamous

Cuboidal

Columnar

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4
Q

Types of GLANDS

A

Unicellular

Multicellular (Simple, unbranched, and Compound, branched)

Exocrine

Endocrine

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5
Q

Types of secretion

A

Serous

Mucous

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6
Q

Mechanisms of secretion

A

Merocrine

Apocrine

Holocrine

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7
Q

Name the cell type

A

Endothelium cells

Simple Squamous

Endothelial nuclei are indicated by arrows

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8
Q

Important characteristics & functions of EPITHELIUM

A

1) covering/lining of all body surfaces – it is derived from all three germ layers
2) have specific apical, laterial, and basal domains
3) Basement membrane: Extracellular membrane attachment of cells to underlying connective tissue
4) Avascular
5) Majority of glands derived from epithelia
5) High regenerative capacity
6) Diversity of function (e.g. protections, secretion, absorbtion)

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9
Q

Name the cell type

A

Epithelium (gall bladder)

Simple columnar

Always look for the simplest form of an epithelium as it will usually be representative (plane of section artifacts can lead to mis-diagnosis)

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10
Q

Name the cell type

A

Epithelium (small intestine)

Simple Columnar

Always look for the simplest form of an epithelium as it will usually be representative (plane of section artifacts can lead to mis-diagnosis)

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11
Q

Transitional cells

A

Large surface cells [umbrella, dome cells], often binucleate. Unique to urinary system – thus also called UROTHELIUM

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12
Q

Cytokeratins

A

Intermediate filaments

All epithelia contain keratin intermediate filaments

Therefore, cytokeratins are diagnostic of epithelia

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13
Q
A

Terminal Bar: Junction Complex

Can be either Zonula Adherens or Zonula Occludens

(can’t distinguish between the two in that picture)

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14
Q

Zonula Occludens: Principal Functions

A

Selective permeability barrier

  • seal intracellular space
  • regulate paracellular transport
  • facilitate/promote transcellular transport

Cell polarity influence

  • separate apical from basolateral domains
  • restrict movement within cell membrane
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15
Q
A

Tight junctions AKA zonula occludens

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16
Q

Zonula Occludens: Principal Components

A

Major integral membrane proteins

  • Claudins
  • Occludin
  • Tricellulin

Peripheral membrane proteina (intracellular)

  • Zonula occludens (ZO) ZO-1, ZO-2, ZO-3
  • Others (eg. cingulin, spectrin)

Cytoskeleton proteins

  • Actin
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17
Q

Tricellulin

A

regulation of paracellular flow

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18
Q

Zonula Adherens: Principal Functions

A

Important belt-like cell-cell adhesion units

(circumferential = zonary)

Functions:

  • Thought to mediate folding and other 3D shapes of epithelia via actin and myosin
  • Tranduce signals from adjacent cells
  • resist mechanical stress
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19
Q

Zonula Adherens: Principal Components

A

Integral membrane proteins (E-cadherins: Ca++ binding, homotypic interactions)

•Peripheral membrane proteins (intracellular)

  • Catenins (α-, β-, γ-)
  • α-Actinin
  • Vinculin

•Cytoskeleton proteins

  • Actin (filamentous) – they are continuous with actin cytoskeleton
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20
Q

Gap junctions

A

A type of lateral surface specialization - Communicating junction

Important spot-like (punctate) cell-cell communication and resource-sharing unites

Channels formed as adjacent connexons align between cell membranes - 6 connexins make up one connexon

found in many tissues and function in electrical synapses

Appoximation to syncytium (multiple nuclei sharing cytoplasm)

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21
Q
A

(Basal Lamina cell)

a. Collagen III
b. Collagen IV, Lamina Densa
c. Lamina Lucida
d. Reticular Lamina
e. Basal Lamina

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22
Q

Basement Membrane

A

Made up of the basal lamina, retucular fibers, and anchoring fibrils (Collagen VII)

Provides physical support; trasmits forces to adjacent CT

Has selective permeability; filter for macromolecules and cell migration barrier

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23
Q

Basal Lamina

A

One component of basement membrane (along with reticular lamina)

Made up of Type IV collagen, laminin (both of which form chicken wire networks), and nidogen

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24
Q

Reticular Lamina

A

One component of the basement membrane (along with basal lamina)

Made up of reticular fibers; mostly collagen III

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25
Describe and Identify
Repiratory tract epithelium Pseudostratified Ciliated Columnar with Goblet cells (photo also contains wandering lymphocytes)
26
Pseudostratified
All cells rest on the basal lamina, but some don't reach the free surface In the respiratory tract, they are specialized for propelling mucus + debris towards the oral cavity
27
Goblet cells
Unicellular epithelial gland pseudostratified eg. trachea simply columnar eg. ntestine
28
Respiratory Tract Epithelial characteristics
Pseudostratified, ciliated columnar with goblet cells
29
Identify and describe
Myoepithelial cells AKA Basket cells Pseudostratified Cells sitting on basal lamina are highly eosinophilic, because there are lots of mitochondria and lots of actin/myosin protein
30
ID type of cells and where it is from
Stratified squamous keratinizing epithelium (SSKE) from the skin
31
Gland formation
All begin as an epithelial ingrowth and all retain keratin expression
32
Exocrine Glands
Maintain contact with surface epithelium, secrete into a lumen
33
Endocrine gland
Lose contact with surface epithelium, secrete into interstitial space
34
Merocrine secretion
Secretions by exocytosis; only the product is released Typical secretions include: - zymogens - sweat - mucous - lysozyme Subcategory: eccrine, referring to sweat secretion from eccrine sweat glands
35
Sebum
Released by holocrin secretion: the entire cell and its contents become the secretory product Note: the phenotypic progression of cells from base to duct - cell borders disappear - nucleus degenerates - cytoplasmic droplets coalesce
36
Holocrin secretion
the entire cell and its contents (sebum) become the secretory product Mechanism of secretion: apoptosis Note phenotypic progression of cells from base to duct: - cell borders disappear - nucleus degenerates - cytoplasmic droplets coalesce
37
What type of gland is this?
Mixed seromucous, a combination of serous and mucous common in a lot of glands
38
Serous
- watery secretion - abundant RER - round nucleus - cells well stained
39
Mucous
- thick secretion - clear cytoplasm - flat nucleus (an artifact of preparation) - cells poory stained
40
Apocrine secretion
aka decapitation secretion; a portion of the apical cytoplasm is released along with the product.
41
Identify type of secretion
This mammary gland exibits both apocrine secretion (large round form) and merocrine secretion (small black circles floating away to the sides of the apocrine secretion)
42
Describe cell type
Simple cuboidal
43
Pseudostratified
44
Stratified Cuboidal
45
Simple columnar
46
Transitional
47
SSNKE
48
Stratified Columnar
49
Simple squamous
50
SSKE
51
Epithelia are derived from...
Ecotoderm - external eg. epidermis Mesoderm - internal eg. pericardial cavity Endoderm - "internal" eg. GI, respiratory tract
52
Epithelia display what kind of intermediate filaments
Keratin Epithelia express keratin intermediate filaments (diagnostic for all epithelia)
53
Two general classes of epithelia
Lining or glandular
54
All epithelia are vascular or avascular?
Avascular
55
Epithelia Functions
_Protection_ (epidermis provides waterproofing, and insulation stomach lining protects from acid, etc.) _Surface transport_ (cilia in respiratory epithelium propel particles upward; oviduct cilia move the ovum) _Absorption_ (microvilli in intestinal epithelium & kidney tubules absorb nutrients) _Secretion_ (both unicellular & multicellular glands) _Trans-epithelial transport_ - apical to basal: kidney tubules transport nutrients from the lumen to basal connective tissue - basal to apical: lymph resorption into lymphatics _Reproductive_ (seminiferous tubule generates sperm) _Special sensory_ (taste buds, hair cells in cochlea) _Contraction_ (myoepithelium)
56
Simple squamous cells of a small vein
57
Simple cuboidal cells of renal tubule
58
Simple columnar cells of intestine
59
Stratified columnar cells of large ducts, conjuntiva
60
stratified squamous keratinizing epithelium (SSKE) eg. skin epidermis
61
stratified squamous non-keratinizing epithelium (SSNKE) e.g. esophagus, anal canal, vagina
62
Pseudostratified, columnar, ciliated with goblet cells in the trachea (aka respiratory epithelium) Pseudostratified: All cells contact basal lamina, not all reach free surface. Typically has cilia except in parts of male reproductive system. (True stratified epithelia NEVER have cilia).
63
Transitional AKA urothelium cells of the urinary system (technically pseudostratified) Large surface cells [umbrella cells], often binucleate. Unique to urinary system – thus also called urothelium
64
65
Myoepithelial cells
AKA basket cells help to expel the secretory products
Histology
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