Epithelium And Glands Flashcards

1
Q

Epithelium

A
  • sheets of cells covering a surface of lining a cavity

- responsible for the major function of most organs

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2
Q

Connective Tissue

A
  • cells and ECM that support and connect other basic tissue types in organs
  • include bone and cartilage and blood
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3
Q

Muscle

A

-contractile tissues

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4
Q

Nervous Tissue

A

-conductive tissues that distribute signals that control various body functions

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5
Q

Characteristics of Epithelial

A
  • continuous sheets
  • rest on basement membrane
  • junctions
  • polarized
  • Surface modifications
  • Avascular - no blood vessels in the actual epithelium
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6
Q

Epithelium Functions

A
  • barrier
  • absorption and secretion
  • removal of particulate matter
  • gas exchange
  • filtration
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7
Q

Surface Modifications

A
  • apical surface:
    1) Microvilli - actin cytoskeleton, increase absorptive surface area, found in GI tract there they promote uptake of nutrients
    2) Stereocilia - very long Microvilli, actin cytoskeleton, increase absorptive SA, found I epididymis where they promote concentration of sperm, not motile
    3) cilia - microtubule cytoskeleton, motile surface extension that move luminal contents, in respiratory tract move particulate matter out of lungs, in female reproductive tract assist in movement of gametes
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8
Q

Microvilli

A
  • increase apical surface area for absorption and secretion
  • actin core provides support to the plasma membrane
  • anchored by terminal web
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9
Q

Cilia

A
  • motile
  • found in locations where movement serves function
  • respiratory epithelium - cilia keep airway free of particulate matter
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10
Q

Basal Surface Specializations

A
  • basal unfolding of the plasma membrane
  • associated with mitochondria
  • high level of transport activity
  • find in proximal convoluted tubule in the kidney and striated ducts of salivary glands
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11
Q

Classification of Epithelial

A
  • based on shape of cells and number of cellular layers
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12
Q

Squamous

A
  • thin, flattened appearance
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13
Q

Cuboidal

A

-height and width are similar

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14
Q

Columnar

A

-height greater than width

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15
Q

Simple

A

-single layer

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16
Q

Stratified

A

-multiple layers

17
Q

Pseudostratified

A

-appears stratified, but all cells touch basement membrane, some do not reach apical surface

18
Q

Transitional

A

-transitional appearance between stratified columnar and stratified squamous and depends on physiological state

19
Q

Simple Squamous

A
  • mesothelium found lining the external surface of internal organs
  • secrets fluid that reduces friction between organs
  • Endothelium found lining the internal surfaces of the heart and blood vessels
  • facilitates transport of fluids, nutrients, metabolites, and gas exchange between flood and surrounding tissues
20
Q

Simple Cuboidal

A
  • lining of ducts of glands, kidney tubules, thyroid follicles
  • taller cells provide additional support
  • cells can be active in transport, synthesis and secretion of substances
  • Height can depend on activity of the cell and range from low to almost columnar
21
Q

Simple columnar

A
  • found lining the digestive tract and uterine tube
  • can have more than one type with different functions
  • absorptive
  • secretory (mucus)
22
Q

Stratified Epithelium

A
  • multiple layers of cells, number of layers varies
  • basal layer rests o basement membrane, upper layers rest on cells below not on the basement membrane
  • uppermost layer at the free surface
  • take their name from the uppermost layer, can be squamous, cuboidal or columnar
  • basal layer can be one type and the upper layer a different type
  • cells in the basal layer may divide to maintain the integrity of the epithelium as upper layers are lost
23
Q

Stratified squamous

A
  • thick and thin skin, non-keratinizing wet skin (mouth)
24
Q

Stratified cuboidal

A

-glandular ducts and large salivary excretory duct

25
Q

Stratified Squamos Epithelium

A
  • 2 types: non-keratinizing, keratinizing
  • provides barrier and protection against abrasion
  • Non-keratinizing is found in moist areas that are subject to abrasion such as oral cavity, esophagus, vagina and anal canal
  • keratinizing is found in skin where upper layers lose their nuclei and contain large amounts of keratin
26
Q

Pseudostratified Epithelium

A
  • may appear stratified
  • nuclei are at different heights making epithelium appear stratified
  • however all cells touch the basement membrane
  • some cells are not as tall as others and the apical surface of the cell may not reach the top of the epithelium
  • found in respiratory tract and epididymis
27
Q

Transitional Epithelium

A
  • found exclusively in the bladder and adjacent regions of the urinary system
  • changes shape depending on the extension of the bladder
  • Relaxed: multiple layers, surface layer has rounded dome cells that are often binucleate
  • Extended - multiple layers, but doesn’t appear as many as relaxed state
28
Q

Glands

A
  • invaginations of sheets of epithelium that grow downward into the underlying connective tissue
  • Exocrine: glands that maintain their connection to the surface, secretory products released into the duct and travel to the surface (sweat glands)
  • Endocrine: glands that lose their connection to the surface, surrounded by capillaries where secretory products enter the blood (adrenal, thyroid)
29
Q

Exocrine

A
  • unicellular, single cell type (goblet cells in intestines)
  • multicellular (most common), Ductal portion, secretory portion
  • Classification:
    1) Structure of the duct (simple or compound)
    2) shape of secretory units ( tubular or actin acinar/alveolar)
    3) Type of secretion (serous, mucous or mixed)
    4) Mechanism of secretion (apocrine, merocrine, holocrine)
30
Q

Duct Shape

A

1) Single duct - simple gland

2) Branched duct - compound gland

31
Q

Secretory unit shape

A
  • tubular gland

- acinar gland is sphere-like in shape

32
Q

Large exocrine gland anatomy: Connective tissue divides gland into lobes and lobules

A
  • Parenchyma - functional component of organ
  • Stroma - supportive CT component of organ
  • Hillum: Doorway for ducts, nerves, and blood and lymph vessels to go to/from gland. These structures course through the CT of trabeculae (septa) to reach parenchyma
33
Q

Mechanisms of secretion

A
  • Apocrine secretion: loss of cytoplasm and apical cell membrane, occurs in mammary gland
  • Merocrine secretion: exocytosis of secretory vesicles, occurs in typical glands (salivary)
  • Holocrine secretion: entire cell is shed and cell breaks down releasing its substance stored in vesicles, occurs in sebaceous glands