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POM (Principles of Medicine) > Epithelia cells and tissues > Flashcards

Epithelia cells and tissues Flashcards

1
Q

What is a tissue?

A

a group or groups of cells whose type, organisation and architecture are integral to its function

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2
Q

What is a tissue made up of?

A

extracellular matrix and fluid

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3
Q

What are the 5 main cell types?

A 
Connective tissue cells
Contractile tissues
Haematopoietic cells
Neural cells
Epithelial cells
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4
Q

What are connective tissue cells?

A

fibroblasts (many tissues), chondrocytes (cartilage), osteocytes (bone)

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5
Q

What are contractile tissue cells?

A

skeletal muscle, cardiac muscle, smooth muscle

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6
Q

What are Haematopoietic cells?

A

blood cells, tissue-resident immune cells, and the cells of the bone marrow from which they are derived

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7
Q

What are neural cells?

A

cells of the nervous system having two main types; neurones (carry electrical signals) and glial cells (support cells)

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8
Q

What are epithelial cells?

A

cells forming continuous layers, these layers line surfaces and separate tissue compartments and have a variety of other functions

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9
Q

What are carcinomas?

A

epithelial cancers

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10
Q

What are sarcomas?

A

mesenchymal (connective tissue and muscle) cancers

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11
Q

What are lymphomas?

or leukemias?

A

haematopoietic cancers

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12
Q

What are neuroblastomas or gliomas?

A

neural cell cancers

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13
Q

What is the function of epithelial cells?

A

transport, absorption, secretion, protection

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14
Q

What is key to the formation and maintenance of epithelial layers?

A

cell-cell junctions

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15
Q

how are epithelial cells classified?

A

their shape

their layering

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16
Q

how are epithelial cells classified by their shape?

A

squamous (flattened plate-shape)
cuboidal
columnar

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17
Q

how are epithelial cells classified by their layering?

A

single layer = simple epithelium

multi-layered = stratified epithelium

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18
Q

Where is the single squamous epithelium found?

A 
lung alveolar (air sac) epithelium, mesothelium (lining major body cavities), endothelium lining blood vessels and other blood spaces). 
THIN
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19
Q

Where is the simple cuboidal epithelium found?

A

in ducts

e.g. those lining the kidney collecting ducts

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20
Q

Where is the simple columnar epithelium found?

A

typical of surfaces involved in absorption and secretion of molecules
-enterocytes(lining the gut)

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21
Q

What are the 2 main types of stratified squamous epithelium?

A

Keratinizing

Non-keratinizing

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22
Q

What is keratinizing Stratified squamous epithelium?

(loose organelles and nuclei) not visible under light microscopy

A

Epithelial cells which produce keratin and in doing so die becoming thicker, stronger, protective structures

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23
Q

Where is keratinizing stratified squamous epithelium found?

A

epidermis (skin epithelium)

24
Q

What is non-keratinizing Stratified squamous epithelium?

A

Epithelial cells which do not undergo keratinisation. They retain their nuclei and organelles

25
Q

Where is non-keratinizing stratified squamous epithelium found?

A

epithelium lining the mouth, oesophagus, anus, cervix and vagina

26
Q

What is pseudo-stratified epithelium?

A

appears to be multi-layered

– On close examination, the surface cells have contact with the basal lamina

27
Q

Where is pseudo-stratified epithelium found?

A

. airway (trachea and bronchi) epithelium, various ducts in the urinary and reproductive tracts

28
Q

Why is epithelial polarity required?

A

to give the directionality needed for epithelial function

29
Q

What are transporting epithelia?

A

transport ions and fluids across epithelial layers

30
Q

What is polarised in the transporting epithelia?

A

pumps and channels
active Na+/ K+ exchanger

only pumping in one aspect of plasma membrane?

31
Q

What is required for secretion from transporting epithelia?

A

polarity

most epithelia secrete in one direction only

32
Q

What are the 4 main cell-cell junctions in epithelia?

A

tight junction
adherens junction
desmosomes
gap junction

33
Q

Where are the tight junctions?

A

form a belt usually around the apical lateral membrane

34
Q

What is the role of tight junctions?

A

sealing gaps between cells

35
Q

What is the role of adherens junctions?

A

controls the formation of all others

36
Q

What are desmosomes?

A

form mechanically tough junctions between cells

37
Q

What is the role of desmosomes?

A

important in tissues required to resist mechanical stresses

38
Q

What is a gap junction?

A

channel forming junction

39
Q

What is the role of the gap junction?

A

form pores between cells and allows cells to exchange and share materials

40
Q

What are mitochondria typically associated with?

A

extensive basal membrane infoldings, providing energy for active transport across the abundant membranes

The infoldings increase the amount of basal membrane that can pump ions and water

41
Q

How is the small intestine surface area increased?

A

it is long, and also by the interior surface of the wall of the small intestine being folded into numerous finger-like processes that point into the interior: the villi (covered with intestinal epithelial cells)

42
Q

What are microvilli?

A

plasma membrane projections of the villi

43
Q

Where are carriers transporting nutrients typically found on the microvillus?

A

brush-border membranes,

e.g. absorptive intestinal cells (enterocytes) and kidney proximal tubule cells

44
Q

What are the 2 main types of secretion?

A

exocrine (into a duct or lumen) and endocrine (into the bloodstream)

45
Q

Where do endocrine cells secrete their contents?

A

into the basal aspect
– secretory vesicles are positioned so that when their contents are released, they have close access to the blood circulation

46
Q

What are the 2 classes of endothelial cells (by the way they secrete)?

A

constitutive

stimulated

47
Q

What are constitutive endothelial cells?

A

secretory vesicles, as they are formed, move directly to the plasma membrane and release their contents

48
Q

example of constitutive endothelial cells?

A

production of plasma proteins by hepatocytes (constitutive endocrine secretion).

49
Q

What are Stimulated endothelial cells?

A

secretory vesicles are stored in the cytoplasm and only fuse with the plasma membrane to release their contents

50
Q

example of Stimulated endothelial cells?

A

release of adrenaline from cells of the adrenal medulla after a fight-or-flight stimulus (stimulated endocrine secretion); when stomach contents enter the duodenum, pancreatic acinar cells are stimulated to release their digestive enzymes into ducts (stimulated exocrine secretion)

51
Q

When calls migrate up the villus epithelium, new cells are made by what?

A

crypt stem cells

52
Q

What happens when the proliferation of intestinal crypt cells are inhibited?
eg. cancer chemotherapy

A

results in loss of the finger-like intestinal villi and flattening of the intestinal mucosa. This is responsible for many of the gastro-intestinal disturbances that are side-effects

53
Q

how are keratinising squamous epithelial cells formed?

A

new cells being formed in the basal layer which migrate up while undergoing a programme of differentiation that eventually leads to them flattening out and keratinising

54
Q

What does hypoproliferation of epithelial cells result in?

A

increased cell numbers and a thickening of cell layers

- in response to repeated or constant pressure

55
Q

What happens if the cell production is greater than the cells lost from the surface?

A

cells will accumulate creating an increased thick hard layer

56
Q

What does papilloma virus do?

A

induces hyperproliferation
– by hijacking the cellular machinery of stratified squamous epithelia and inducing increased cell proliferation, which results in a surface growth, e.g. a wart

POM (Principles of Medicine) (17 decks)

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