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Histology > Characteristics of Epithelial Tissues 1 > Flashcards

Characteristics of Epithelial Tissues 1 Flashcards

1
Q

Epithelial Tissues are the most what in the body?

A

Cellular , no matrix and tons of cells

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2
Q

How are epithelium tissues broken up?

A

-Epithelia tissues are divided into simple(one cell layer thick) and stratified(more than one cell layer thick) depending on the number of cell layers that make up specific epithelial tissue -Epithelial tissues are also classified according to the predominant shape of the cells that make up the superficial layer of the tissues -Lots of exceptions to these rules

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3
Q

Chareacteristics of general cells vs Epithelial

A

-Cels typically have a relatively uniform geomteric shape when viewed fom the side -Cells are tightly bound together to form tisues by highly specialized molecule complexes that form tight junctions -epithelial tissues have relatively little intercellular matrix -epithelial tisseus typically display free surfaces -epitheliod tissues resemble epithelial tissuses but lack a free surface

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4
Q

Apical domains

A

Are the surfaces of hte cells that are in contact with a lumen(ie. kidney tubule cells, glandular duct cells) or external environment(surface cells of the epidermis)

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5
Q

Basolateral Domains

A
  • these include the surfaces of cells that are locked together by special junctions complexes with neighboring cells as well as the surface opposite the apical domain that is in contact with the basal lamina -further charecterized by these special junctions which hold cells together and communicate with neighboring cells
  • Basolateral domains are charecterized by these special junctions which hold cells together and communication with neighboring cells
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6
Q

Where can epithelial tissues be derived from?

A
  • Epithelial tissues do not contain blood vessels
  • Can be derived from:
    • Ectoderm
      • ex. The skin epidermis and glands
    • Endoderm
      • ex. the lining of the gastrointestinal tract(including glands)
    • Mesoderm
      • ex. the lining of blood vessels, mesothelium, Bowman’s capsule
  • epithelial tisseus are close enough to blood vessels that they receive nutrients from blood vessels through diffusion
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7
Q

Where do epithelial tissues sit on and what components make up this membrane

A
  • Basement membrane consists of two components:
    • The basal lamina is next to the epithelial layer and is 50-80nm thick. It is composed of type IV collagen plus glycoproteins and is PAS+. It is absent in lymph vessels and hepatic sinusoids
    • Reticular lamina is in contact with underlying connective tissue and consists of argyrophilic fibers, reicular fibers and glycoproteins
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8
Q

Function of the basement membrane?

A
  • Selective filtration barrier
  • Scaffold for embryogenesis and regeneration
  • Stabilization of tissue shapes
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9
Q

Characteristics of the Epithelial tissue

A
  • Epithelial tissue line body cavities and cover body surfaces
  • Epithelial tissue form secretory and excretory parts of glands
  • Epithelial tissues may be innervated
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10
Q

Classification according to number of cell layers

A
  • Simple(one layer)
  • Stratified(more than one layer)
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11
Q

Classification according to the shape of the most superficial layer of cells as seen in a side view

A
  • Squamous(flattened)
  • Cuboidal(height approximately equal to width)
  • Columnar(height greater than width)
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12
Q

Classification according to the surface modifications on the apical domains of teh outermost cell?

A
  • Cilia
  • Stereocilia
  • Microvilli(brush border)
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13
Q

Can be classified by presence or absence of keratin

A
  1. Lightly keratinized in esophagus and vagina
  2. Heavily keratinized in epidermis
  3. Keratin is a dead protein, and secreted by cells, and water proofing protecting layer
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14
Q

Pseudostratified

A
  • Type of simple epithelium
  • Epithelium appears to be stratified ,but all cells are in contact with the basal lamina, so it is technically a simple epithelium. The appearance of stratification is due to the variable positions of the nuclei within the cells.
  • Pseudostratified arrangement of some epithelia may reflect the role of stem cells(the shorter cells in the layer) that are necessary to balance cell turnover by replacing more mature cells when they become aged or damaged
  • If you all have cells in contact with the basal lamina it has to be simple epithelium, however the nuculei occupy varying positions and some can be close to basal lamina and other places
  • The taller cells are more mature cells, who need to be replaced by the younger cells
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15
Q

Transitional

A
  • Type of simple epithelium but with the appearance of having more than one layer because of hte positions of the nuclei
  • Again,all cells are in contact with the basal lamina , but the domeshaped surface cells give the appearance of stratified epithelium
  • Category of epithelium is associated with the urinary track and may be referred to as urothelium
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16
Q
A

Simple Squamos epihelium

  • The inner lining of all blood vessels consists of a single layer of squamos endothelial cells
  • The thinness of hte simple squamos epithelial cells reflects their primary function in rapid exchange of substance between blood and tissue
  • cover the peritoneum,pleura and pericardium
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17
Q
A

Simple Cuboidal

  • Inner lining of kidney tubules and thyroid follicles consist of a single layer of cuboidal cells
  • Cuboidal cells are highly polarized and participate in absorption,secretion(thyroid gland) and active ion transport(kidneys)
  • Similiar to the endothelium, a basal lamina attaches the cell to the subjacent connective tissue
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18
Q
A

Simple columnar

  • The small intestine is lined by columnar epithelial cells with the nuclues in the medial portion of the cell
  • Apical domain contains finger like projections called microvilli forming a brush border
  • Microvilli participate in the absorption of proteins , sugar and lipids which aer released at the basolateral domain into the blood circulation for transport
  • Goblet cellsare present among the columnar epithelial cells
    • distinguished by a distal goblet like apical cytoplasm containg a light stained mucus material
    • Mucus is relaesd into the lumen and coats the epithelial cell surface
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19
Q
A

Stratified Squamous epithelium with moderate keratin

  • Consists of undifferentiated basal cells specialized for mitotic division
  • Stratified cells covering the basal layers are differentiating cells
  • cells of hte outer layer are highly differentiated:they increase their keratin content to protect the tissue from the mechanical action of ingested food
  • Outermost cells retain their nuclei
    • Also known as nonkeratinizing
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20
Q
A

Stratified squamos epithelium with abundant keratin

  • highly keratinized epthelium consists of undifferentiated basal cells specialized for mitotic division
  • Stratified cells covering the basal layer are differentiating cells
  • Cells of the outer layer contain abundant keratin to prevent water loss and penetration of chemical and physical insults
  • Outermost cells lack nuclei aka keratinizing
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21
Q

Pseudostratified

A
  • type of simple epithelium
  • Appears to be stratified but all cells are in contact with the basal lamina , so it is technically a simple epithelium
  • appearance of stratification is due to the variable positions of the nuclei within the cells
  • Pseudostratified arrangement of some epithelia may refelct the role of stem cells(shorter cells in the layer) that are necessary to balacne cell turnover by replacing more mature cells when they beomce aged or damaged
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22
Q
A

Pseudostratified columnar

  • muclei are located on different levels
  • its always columnar
  • goblet cells are white bubbles adn mucus producing cells
23
Q

Transitional

A
  • Thought to be a type of simple epithelium but with the appearance of having more than one layer becasue of the positions of nuclei
  • Again all cells are in contact with the basal lamina , but the domeshaped surface cell give the apperaance of stratified epithelium
  • Category of epithelium associated with the Urinary track and may be referred to as urothelium
24
Q
A

Transitional epithelium

  • Dome shape is not typical and only find it in transitional epithelium
  • transitional epithelium lining the urinary passages consists of two cell types
    • Dome shaped columnar cells extending from the basal lamina to the lumen
    • Basal cells attached to the basal lamina
  • Some species the urothelium apperas as a pseudostratified epithelium;in other species it has the appearance of a stratified squamos epithelium
  • Charecteristic of the urothelium is that superficial cells respond to tensional forces–by changi ntheir geometry and surface dome shape configuration
  • Plaques of aggregated proteins are found onthe apical plasma membrane of the columnar cells
25
Q
A

Pseudostratified columnar ciliated epithelium(trachea)

  • Epithelium consists of three major cell types
    • Columnar cells with cilia on their apical domains
    • Basal Cells anchored to the basal lamina
    • Goblet cells-mucus secreting epithelial cells
  • Columnar cilia and golbet cells attach to the basal lamina and reach the lumen
  • Basal cells do not reach the lumen
26
Q
A

Pseudostratified columnar epithelium with stereocilia(epididymis)

  • Epididymal epithelium contains two major cell types
    • columnar cells with stereocilia and highly developed golgi appartus(called prinicpal cells)
    • Basal cells attached to the basal lamina
  • Basal and princiapl cells are associated with the basal lamina
  • Only principal cells reach the lumen
  • Sperm can be visualized in the lumen
27
Q

Apical doamins and modifications

A
  • Charecterized by surface modifications such as cilia or microvilli
  • Apical domains face a lumen or exernal environment
  • Surface modifications
    • Cilia
    • Microvilli(brush border)
    • Stereocilia
28
Q

Basolateral domains

A
  • Sides and bases of the cells are charecterized by intercellular junctions
  • These cell surfaces are in contact with the basement membrane(basal domain) and surrounding cells(lateral domains)
29
Q

Basolateral Surface Modifications

A
  • Epithelial tissues often function to maintain concentration differences
  • some epithelial tissues form a tight barrier while others form a leaky barrier
  • Type of barrier is determined in part by the mlecular coplexes that hold the epithelial tissues together along the alteral domains
  • Epithelial cells are also held tightly to a non-cellular basal lamina(basement membrane) that helps to anchor and stabilize the epithelial tissue layer
30
Q

Location of simple squamous epithleium

A
  • Lines lumina of ducts,vessels , and other tubular strucutres
  • Forms walls of alveoli,Bowman’s capsules and inner surfaces of membranous labyrinth and tympanic membrane
31
Q

Locations of simple cuboidal Epithelium

A
  • In side view cells may be lor or high(approaching almost squamous or almost columnar)
  • May have a brush border(kidney tubules) on apical surface composed of microvilli
  • Found on surface of ovary ,pigmented epithelium of retina, kidney tubules , glands and ducts,terminal bronchioles, choroid plexus and anterior capsule of lens of eye
32
Q

Locations of Simple columnar epithelium

A
  • May have a striated border(intestinal cells) on apical surface composed of microvilli
  • Ciliated columnar epithelium is found in the upper respiratory tract , uterine tubes, uterus , paranasal sinuses and the central canal of the spinal cord
  • Non-ciliated columnar epithelium is found in the digestive tract beginning with the cardia of the stomach, the gall bladder , and in parts of the excretory ducts of glands
33
Q

Location Stratified squamos Epithelium

A
  • Heavily keratinized stratified squamos epithelium is found i nthe epidermis with connective tissue papillae and in the cornea without connective tissue papillae
  • Lightly or non-keratinized stratified squamos epithelium is found in the esophagus , vagina, lining of hte mouth, tongue , and part of hte epiglottis
34
Q

Location Stratified cuboidal epithelium

A
  • Seldom found, but may occur in small areas of the anal mucosa , large excretory ducts of some glands adn aprt of the male urethra
35
Q

Location Stratified Columnar epithelium

A
  • Seldom found;ocurs in the ducts of adult sweat glands , fornix of the cnojunctiva of the eye , parts of hte male reproductive/urinary tract, the pharynx , and the epiglottis
36
Q

Location Pseudostratified epithelium

A
  • Ciliated pseudostratified columnar epithelium is found in the trachea
  • Pseudostratified epithelium with stereocillia is found in the epididymis
    • Stereocilia are similar to microvilli but are longer and are often branched
37
Q

Location of transitional epithelium

A
  • Associated with urniary system
  • referred to as urothelium
38
Q

Functions of epithelial tissues

A
  • Two kinds of epithelium
    • Covering and lining
    • Glandular
  • Involved in secretion or absorption are typically simple or pseudostratified
    • Height of cell often refelcts the level of secretory or absorptive activity
    • Simple columnar epithelium functions primarily in secretion of enzymes and mucous and absorption of nutrients and fluids
      • Lining of gallbladder
      • Proximal convoluted portion of renal tubule
    • High columnar tubes need to have more space if it’s invovle with transporting a lot of nutrients
    • Low columnar if nto invovled with transporting material out of the cell
39
Q
A

Stratified Squamos

Highly nucleated and non keratinized

40
Q
A

Stratified Squamos

Hevaily keratinized

41
Q
A

Simple Cuboidal

Lots of tubules

42
Q
A

Stratified squamos

Non keratinized

outermost laeyr nucleated

43
Q
A

Simple Cuboidal

Longitudinal tubule

44
Q
A

Simple columnar

see goblet cells

45
Q
A

Transitional epithelium

46
Q
A

Simple Columnar

47
Q
A

Pseudostratified columnar

48
Q
A

Simple Cuboidal

49
Q
A

Transitional epithelium

50
Q
A

Simple low cuboidal

51
Q
A

Simple Columnar Epithelium

52
Q
A
53
Q
A
54
Q
A

Histology (12 decks)

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