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Block 1 > Epithelium Classification > Flashcards

Epithelium Classification Flashcards

1
Q

Simple squamous epithelium are found where?

A
  1. Lining of Vascular System
  2. Lining of Body Cavities
  3. Kidney (Bowman’s Capsule)
  4. Lung (Respiratory Spaces)
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2
Q

Simple squamous epithelium function as?

A
  1. A barrier
  2. Diffusion O2 CO2 due to their thinness
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3
Q

Specialized simple squamous epithelium that line the inside of blood vessels and the heart?

A

Endothelium (prevent coagulation of blood)

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4
Q

Specialized simple squamous epithelium that line body cavities such as pericardial, peritoneal, and plural cavities?

A

Mesothelium

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5
Q

Malignant tumors that derive from the mesothelium?

A

Plural Mesothelioma

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6
Q

What are the features of simple cuboidal epithelial cells?

A

Cell height=Cell Width

Single Layer

Round Nuclei

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7
Q

What are the features of simple squamous epithelial cells?

A

Flattened cells, scale like, flattened nuclei

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8
Q

Where are simple cuboidal epithelium found?

A
  1. Kidney Tubules
  2. Ducts/Glands
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9
Q

Simple cuboidal epithelium function?

A

Barrier

Absorption

Secretion

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10
Q

What are the features of simple columnar epithelium?

A

Tall Columnar

Oval-Shaped Nuclei

Surface Modifications: Microvilli, Cilia

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11
Q

Where are simple columnar epithelium found?

A
  • GI Tract and Gallbladder
    • Non-Ciliated Type
  • Oviduct
    • Ciliated Type
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12
Q

What are the functions of simple columnar epithelium?

A

Absorption

Secretion

Lubrication

Transport

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13
Q

What are the features of pseudostratified columnar epithelium?

A

Columnar Cells and Basal Cells

Oval-Shaped Nuclei

Ciliated: Trachea, Bronchi

Non-Ciliated: Epidymis, Prostate

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14
Q

Where are ciliated pseudostratified columnar epithelium found?

A

Trachea and Bronchi

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15
Q

What function do ciliated pseudostratified columnar epithilial cells carry out?

A

Protection

Movement of Mucus

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16
Q

Where are non-ciliated pseudostratified columnare epithelium found?

A

Epididymis

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17
Q

What is the function of non-ciliated pseudostratified columnare epithelium?

A

Absorption

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18
Q

What are the features of stratified squamous epithelium?

A

Top layer is flat

Multiple cell layers

19
Q

Keratinized stratified squamous epithelium are found wear?

A

Skin (Epidermis)

20
Q

Non-keratinized stratified squamous epithelium are found where?

A

Oral Cavity

Esophagus

Vagina

21
Q

What are the functions of both keratinized and non-keratinized stratified squamous epithelium?

A

Barrier

Protection

22
Q

What are the features of stratified cuboidal epithelia?

A

Cube Shaped Basal Layer

Round Nuclei

Apical Layer: Cuboidal

23
Q

What are the features of stratified columnar epithelia?

A

Cube-Shaped Basal Layer

Round Nuclei

Apical Layer: Columnar

24
Q

Where are stratified cuboidal epithelium found?

A

Sweat Gland Ducts

Exocrine Glands

25
Q

What is the function of stratified cuboidal epithelium?

A

Barrier

Conduit

26
Q

Where are stratified columnar epithelium found?

A

Large ducts of glands (ie. Parotid Salivary Glands)

27
Q

What is the function of stratified columnar epithelium?

A

Barrier

Conduit

28
Q

What are the features of transitional epithelium?

A

Multiple Layers

Variable Cell Shape

Surface Layer of dome cells that are often binucleated

Ability to Stretch

29
Q

Where are transitional epithelium found?

A

Urinary System: Ureter, Bladder, Kidney

30
Q

What is the function of translational epithelium?

A

Protection

Barrier

31
Q

Apical Domain

A
  • Forms external/luminal surface of the cell
  • Exhibit various modifications
    • Microvilli (Can’t see in lab)
      • Increase surface area (absorption)
        • Small Intestine, Kidney
      • Size - 1 x 0.01 micrometer
      • Core is formed by actin filaments bound together by fimbrin and fascin anchored into the membrane by lateral anchoring proteins such as myosin I
      • Amorphous apex formed by villin by which the actin filaments anchor into
    • Stereocilia
      • Uncommon modified microvilli
      • Long and sometimes branching
      • Core formed by actin filaments similar to microvilli
      • Found in the epididymis (absorption) and inner ear cochlea (sensory receptors)
    • Cilia
      • Move substances along the surface of the epithelium
        • Respiratory tract and oviduct
      • Formed by 10 pairs of microtubule (axoneme)
        • 9 doublets and 1 central pair
      • Thicker than microvilli 2-10 x 0.25 micrometers
        • Base is attached to centriole/basal body
          • 9 triplets
      • Primary ciliary dyskinesia
        • Dextrocardia
        • Impaired development of skull air sinuses
        • No mucus removal from lunds ->infection
        • Infertility
    • Secretory Vesicles
      • Present in epithelium involved in production and secretion of macromolecules
32
Q

Lateral Domain

A
  • Cell junctions - allows functioning as a whole
    • Occluding Junctions (Tight)
      • Apically oriented
      • Zonula occludens
        • Virtually impermeable, functions to prevent diffusion by blocking paracellular pathways (4 nm)
      • Formed by sealing strands of transmembrane proteins
      • Found in cells with secretory or absoptive roles
    • Anchoring Junctions
      • Provide stability and mechanical strength by connecting adjacent cytoskeletons
      • Two major types
        • Zonula Adherins
          • Connect actin to actin and not as tight at occluding junctions (20 nm)
          • Composed of:
            • Actin binding proteins
              • Vinculin, alpha-actinin
            • Peripheral protein
              • Cadherin family (Ca2+ dependent)
                • Plays important role in control of cell behavior
        • Macula adherins (desmosome)
          • Connects intermediate filaments
          • Epidermis of skin and muscle
          • Composed of:
            • Intracellular plaque
              • Made of desmoplakin
              • Intermediate filaments go throught the plaque
            • Transmembrane Proteins
              • Cadherin family
          • Pemphigus disease
            • body produces abnormal antibodies to the proteins forming desmosomes
            • Presents as blistering of skin and mucous membranes
    • Communicating Junctions (Gap Junctions)
      • Allow diffusion of small molecules and ions b/t adjacent cells
      • Intercellular channels (2.8 nm in diameter)
        • Formed by a pair of connexons
          • Each consists of 6 connexins
      • Usually occur in patches
      • Most common in epithelia, cardiac, smooth musclem, and embryonic tissues
        • Communication and cell proliferation
33
Q

Basal domain

A
  • Basement membrane
    • Separates epithelium from underlying connective tissue
    • 2 Layers
      • Basal Lamina
        • Most external layer that belongs to the epithelium
        • Mostly composed of sheets of collagen type IV and laminin
      • Reticular lamina
        • Deeper layer that belongs to the connective tissue
        • Mostly composed of thin collagen fibers (Type III)
  • Epithelial cells attach via anchoring junctions
    • Focal Adhesions
      • Attach actin cytoskeleton of cell to extracellular matrix
      • Composed of
        • Actin-binding proteins
          • Vinculin, alpha-actinin attach to microfiliaments
        • Peripheral protein
          • Talin
            • Connects actin binding proteins to transmembrane proteins
        • Transmembrane proteins
          • Integrin (Ca2+ dependent)
    • Hemidesmosomes
      • Attach intermediate filaments from cell cytoskeleton to extracellular matrix
      • Composed of:
        • Intracellular plaque (made of desmoplakin)
          • Intermediate filaments end on plaque
        • Transmembrane proteins
          • Integrin family - attach to extracellular proteins
34
Q

Differentiate between exocrine and endocrine glands.

A
  • Endocrine glands
    • Secrete their product into the intercellular space or underlying tissue which then diffuse into the blood
    • Cells usually arranged in cords along capillaries that supply the gland
  • Exocrine glands
    • Secrete their product into ducts or spaces lined with epithelium
    • Cells usually arranged in acini or tubules
35
Q

What are the major mechanism of secretion for exocrine glands?

A
  1. Merocrine
  2. Apocrine
  3. Holocrine
36
Q

Describe merocrine glands.

A
  • Secretory product is delivered in membrane bound vesicles to the apical surface
    • Fuse with membrane and release via exocytosis
  • Three subtypes
    • Serous glands
      • Secrete thin, watery, protein rich secretion
      • Vesicles small and densely stained
      • Better developed RER than mucous cells
        • Cell cytoplasm stains more basophilic
      • RER occupies basal part of cell forcing nuclei to middle of the cell
      • Cells are usually pyramidal in shape
        • Serous acini rounded in shape
      • Example: pancreas and parotid salivary gland
    • Mucous glands
      • Produce mucins that consist of long chains of negatively charged carbohydrates attached to a small protein core
        • Mucins are viscous and important to lubrication and protection
      • Secretory granules are large and stain very lightly w/ H&E
      • RER not well developed
      • Nuclei are heterochromatic and occupy the basal position
      • Cells columnar in shape
        • Mucous acini have a tubular shape
      • Example: Goblet cells, glands of soft palate, Brunner’s glands
    • Mixed glands (Seromucous glands)
      • Have both serous and mucous glands
        • Mucous cells form tubules capped by serous cells that form serous demilunes
      • Example: Submandibular salivary gland
37
Q

Describe apocrine glands.

A
  • Secretion of product involves pinching of the apical cytoplasm w/ the formation of secretory vesicles
    • Found in mammary gland where it is responsible for releasing large lipid droplets into milk
38
Q

Describe holocrine glands.

A
  • Secretion involves whole cell rather than its parts
    • Cells accumulate secretory product and goes through apoptosis resulting in both the cellular content and cell debris to be released into the lumen of the gland
    • Typical of sebaceous glands of the skin
39
Q

Describe unicellular glands.

A
  • Individual secretroy cells scattered within non-secretory epithelium
    • Goblet cells are the most common
      • Specialized for the secretion of mucus
      • Scattered within the columnar epithelia of the GI and respiratory tracts
40
Q

Describe multicellular exocrine glands.

A
  • Composed of more than one cell
  • Most form tubular invaginations from the surface
    • Allows increase in surface area
    • Terminal part = secretory portion
      • Serves as a duct
        • Connects secretory cells to the surface
      • If shaped like a flask = alveolar or acinar
        • Most often serous
      • If shaped like a tube = tubular
        • Most often mucous
      • If secretory tube ends with a flask-shaped dilation = tubuloalveolar
        • Always mixed/seromuscous
41
Q

Describe myoepithelial cells.

A
  • Are contractile cells present in some glands between the basal lamina and in the secretory portion of glands and ducts
    • Contain contractile proteins (myosin)
    • Contraction causes expulsion of secretory product
    • Present in sweat glands, salivary glands, and in the mammary gland
42
Q

Cancer derived from barrier epithelium

A

Carcinoma

43
Q

Cancer derived from glandular epithelium

A

Adenocarcinoma

Block 1 (12 decks)

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