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Massage Therapy! > Epithelial Tissue > Flashcards

Epithelial Tissue Flashcards

1
Q

Epithelial Tissues

A
  • large sheets of cells covering all surfaces of the body exposed to the outside world and lining the outside of organs
  • also forms much of the glandular tissue of the body
  • skin, airways, urinary/reproductive system, hollow organs, and body cavities that don’t connect to the exterior of the body (blood vessels, serous membranes)
  • nearly completely avascular (no blood vessels
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2
Q

where do they derive from?

A
  • all 3 major embryonic layers
  • epithelia lining skin, parts of mouth and nose and anus develop from ectoderm
  • cells lining airways and most of digestive system originate in endoderm
  • epithelium that lines vessels in the lymphatic and cardiovascular systems derives from mesoderm –> called endothelium
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3
Q

what structural and functional features do they share?

A
  • tissues are highly cellular
  • little or no extracellular material between cells
  • adjoining cells form cell junction
  • exhibit polarity with differences in structure/function between the exposed surface of the cellj
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4
Q

cell junction

A

adjoining cells form specialized intercellular connection between cell membranes

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5
Q

apical

A

surface of the cell and basal surface close to underlying body structures

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6
Q

basal lamina

A

mixture of glycoproteins and collagen
- provides attachment site for epithelium, seperates it from underlying connective tissue
- attatches to reticular lamina to form basement membrane

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7
Q

basement membrane

A

basal lamina attatched to reticular lamina
- holds everything together

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8
Q

how do epithelial tissues get nutrients?

A
  • nutrients come by diffusion or absorption from underlying tissues or the surface
  • capable of rapidly replacing damaged and dead cells
    –> characteristic of surface epithelium that allows our airways and digestive tracts to rapidly replace damaged cells w new cells
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9
Q

what is the body’s first line of protection from physical, chemical and biological wear and tear?

A

epithelial tissues
- act as gatekeepers of body to control permeability and allow selective transfer of materials across physical barrier

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10
Q

functions of epithelium

A
  • first line of protection
  • gatekeepers
  • selective transport
  • capable of secretion and release of mucous
  • releases digestive enzymes (in the small intestine)
  • cells lining the respiratory system secrete mucous that traps incoming microorganisms and particles
  • glandular epithelium contains many secretory cells
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11
Q

Epithelial Cells

A
  • characterized by polarized distribution of organelles and membrane-bound proteins between their basal and apical
  • certain structures found in epithelial cells are an adaptation to specific functions: certain organelles are segregated to basal sides, other organelles and extensions (like cilia) are on apical surface
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12
Q

cilia

A
  • microscopic extensions of the apical cell membrane that are supported by microtubules
  • they beat in unison and move fluids and trapped particles
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13
Q

ciliated epithelium

A
  • lines the ventricles of brain where it helps circulate the cerebrospinal fluid
  • The ciliated epithelium of your airway forms a mucociliary escalator that sweeps particles of dust and pathogens trapped in secreted mucous toward the throat
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14
Q

mucociliary escalator

A
  • sweeps dust particles and pathogens trapped in mucous towards the throat
  • called escalator bc it continuously pushes mucous with trapped particles upward
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15
Q

nasal cilia

A

sweeps the mucous blanket down towards your throat

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16
Q

common between nasal cilia and mucociliary escalator

A
  • transported materials are usually swallowed
  • end up in acidic environment of your stomach
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17
Q

what are the 3 types of cell junctions

A
  1. tight junctions
  2. anchoring junctions
  3. gap junctions
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18
Q

what are tight junctions

A
  • separates the cells into apical and basal compartments
  • two adjacent epithelial cells form a tight junction
  • no extracellular space between them
  • movement of substances through the extracellular space between cells is blocked
  • enables epithelia to act as selective barriers
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19
Q

what are anchoring junctions

A
  • several types of celljunctions that help stabilize epithelial tissues
  • common on lateral and basal surfaces of cells where they provide strong and flexible connections
  • 3 types: desmosomes, hemidesmosomes, adherens
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20
Q

what are desmosomes?

A
  • type of anchoring junctions
  • occurs in patches on membranes of cells
  • patches are structural proteins on inner surface of cells membrane
  • the adhesion molecule (cadherin) is embedded in patches and projects through cell membrane to link with cadherin molecules of adjacent cells
  • these connections are especially important in holding cells together
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21
Q

hemidesmosomes

A
  • type of anchoring junction
  • look like half a desmosome
  • link cells to extracellular matrix (like basal lamina)
  • similar in appearance but they include adhesion proteins called integrins instead of cadherins
  • use either cadherins or integrins depending on contractile protein actin located on cytoplasmic surface of cell membrane
  • actin can connect isolated patches or form belt-like structure inside the cell
  • these junctions influence the shape and folding of epithelial tissue
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22
Q

gap junction

A
  • not the same as tight and anchoring junctions
  • forms intercellular passageway between membranes of adjacent cells to facilitate the movement of small molecules and ions between cytoplasm of adjacent cells
  • junctions allow electrical and metabolic coupling of adjacent cells, which coordinates function in large group cells
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23
Q

how are epithelial tissues classified?

A

according to shape of cells and number of cell layers formed

24
Q

what are the different cell shapes?

A
  • squamous (flattened and thin)
  • cuboidal (boxy, as wide as it is tall)
  • columnar (rectangular, taller than it is wide)
25
Q

what is it called when it has more than one layer

A

stratified

26
Q

pesudostratified

A
  • pseudo: false
  • tissue with single layer of irregularly shaped cells that give appearance of more than one layer
27
Q

transitional

A
  • form of specialized stratified epithelium in which the shape of cells can vary
28
Q

true or false: shape of cells in single cell layer of single epithelium reflects the function

A

true

29
Q

what does squamous cell nuclei look like

A

flat, horizontal, elliptical (mirrors form of cell)

30
Q

endothelium

A
  • epithelial tissue that lines vessels of lymphatic and cardiovascular system
  • made up of a single layer of squamous cells
31
Q

simple squamous epithelium

A
  • thin scale like cell
  • present where rapid passage of chemical compounds is observed
    ex: alveoli of lungs, segments of kidney tubules, lining of capillaries
32
Q

mesothelium

A
  • simple squamous epithelium that forms surface layer of serous membrane that lines body cavities and internal organs
  • function: provide smooth and protective surface
33
Q

mesothelial cells

A
  • squamous epithelial cells that secrete fluid that lubricates mesothelium
34
Q

what does simple cuboidal epithelium

A
  • nucleus of box-like cells appears round
  • located near center of cell
  • epithelia are active in secretion and absorptions of molecules
    EX: observed in lining of kidney tubules and ducts of glands
35
Q

simple columnar epithelium

A
  • nucleus of tall column-like cells tends to be elongated and located in basal end of cells
  • epithelium is active in absorption and secretion of molecules
  • forms the lining of some secretions of the digestive system and parts of the female reproductive tract
36
Q

ciliated columnar epithelium

A
  • simple columnar epithelial cells with cilia on apical surfaces
  • found in lining of fallopian tubes and parts of respiratory system
  • function: beating of cilia helps remove particulate matter
37
Q

pseudostratified columnar epithelium

A
  • appears stratified but instead consists of single layer of irregularly shaped and differently sized columnar cells
  • nuclei of neighboring cells appear at different levels rather than clustered in basal end
  • all cells are in contact w basal lamina (even tho it doesnt look like it), some dont reach apical surface
    EX: respiratory tract (some have cilia)
38
Q

true or false: simple and pseudostratified cuboidal epithelia are heterogeneous bc they include additional types of cells interspersed among epithelial cells

A

false – simple and pseudostratified columnar epithelia

39
Q

goblet cell

A
  • mucous-secreting unicellular ‘gland’ interspersed between columnar epithelial cells of mucous membranes
40
Q

stratified epithelium

A
  • several stacked layers of cells
  • protects against physical and chemical wear and tear
  • named by shape of most apical layer of cells (closest to free space)
41
Q

stratified squamous epithelium

A
  • most common tpype of stratified epithelium in human body
  • apical cells are squamous
  • basal layer mgiht be columnar or cuboidal
  • top layer: covered with dead cells filled with keratin
    EX: mammalian skin
42
Q

stratified cuboidal epithelium and stratified columnar epithelium

A
  • found in certain glands and ducts
  • uncommon in human body
43
Q

transitional epithelium

A
  • another kind of stratified epithelium
  • gradual changes in shapes of apical cells as bladder fills with urine
  • only found in urinary system: ureters and urinary bladder
  • when bladder is empty: epithelium is convoluted and has cuboidal apical cells w convex umbrella-shaped apical surfaces
  • bladder filled: epithelium loses its convolutions and apical transition from cuboidal and squamous, more stretched out and less stratified
44
Q

Gland

A

structure made up of one or more cells modified to synthesize and secrete chemical substances
- consist of groups of epithelial cells
- can be classified as endocrine or exocrine glands

45
Q

endocrine gland

A
  • ductless gland that releases secretions directly into surrounding tissues and fluids
  • secretions of endocrine glands are hormones
    –> released into interstitial fluid, diffused into bloodstream and dleivered to targets (cells that have receptors to bind the hormones)
  • part of major regulartory system coordinating the regulation and integration of body responses
    ex: anterior pituitary, thymus, adrenal cortex, gonads
46
Q

exocrine glands

A
  • secretions that leave through duct that opens directly/indirectly to external environment
  • release contents through duct that leads to epithelial surface
    EX of secretions: mucous, sweat, saliva, and breast milk
  • all discharged through tubular ducts
  • secretions into lumen of the gastrointestinal tract (technically outside the body)
47
Q

glandular structure

A
  • exocrine are either unicellular or multicellular
48
Q

unicellular glands

A
  • scattered single cells
  • such as goblet cells (found in mucous membranes of small and large intestine
49
Q

multicellular exocrine glands

A
  • aka serous glands
  • develop from simple epithelium to form a secretory surface that secretes directly into an inner cavity
  • glands line the internal cavities of the abdomen and chest and release their secretions directly into the cavities
  • other multicellular exocrine glands release their contents through a tubular duct (duct is single in a simple gland but in compound glands, is divided into one or more glands)
  • tubular glands –> ducts can be straight or coiled
  • alveolar (acinar) –> tubes that form pockets (an exocrine portion of the pancreas)
  • combination of tubes and pockets are known as tubuloalveolar (tubuloacinar) compound glands
  • branched gland: duct connected to more than one secretory group of cells
50
Q

what do the exocrine glands mode of secretion and nature of released substances look like?

A
  • merocrine secretion
  • apocrine secretion
  • holocrine secretion
51
Q

merocrine secretion

A

merocrine secretion: most common type of exocrine secretion
- secretions are enclosed in vesicles that move to the apical surface of cell where ocontents are released by exocytosis
EX: watery mucous containing the glycoprotein mucin is a lubricant that offers some pathogen protection is a merocrine secretion
- eccrine glands that produce and secrete sweat are another example

52
Q

apocrine secretion

A
  • accumulates near the apical portion of the cell
  • that portion of the cell and its secretory contents pinch off from the cell and are released
  • apocrine sweat glands in the axillary and genital areas release fatty secretions that local bacteria break down (causes body odor)
53
Q

what happens in both merocrine and apocrine glands

A

both continue to produce and secrete their contents with little damage caused to the cell because the nucleus and gogi regions remain intact after secretion

54
Q

holocrine secretion

A
  • involves the rupture and destruction of the entire gland cell
  • cell accumulates its secretory products and releases them only when it bursts
  • new gland cells differentiate from cells in the surrounding tissue to replace those lost by secretion
  • the sebaceous glands that produce the oils on the skin and hair are holocrine glands/cells
55
Q

Serous Gland

A
  • produces watery, blood-plasma-like secretions rich in enzymes such as alpha amylase
  • common in salivary glands of mouth
  • mixed exocrine glands have both serous and mucous glands and release both types of secretions
56
Q

Mucous Gland

A
  • releases watery to viscous products rich in the glycoprotein mucin
  • common in salivary glands of the mouth
  • mixed exocrine glands have both serous and mucous glands and release both types of secretions

Massage Therapy! (20 decks)

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