Epithelium I Flashcards

1
Q

What is epithelial tissue?

A

A group of tissues found covering the body

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2
Q

What is epithelial tissue made up of?

A

Closely packed cells in 1 layer or multilayers

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3
Q

What is epithelium derived from?

A

Embryo germ layers

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4
Q

How many embryo germ layers do humans have?

A
  • 3
    1. Endoderm
    2. Mesoderm
    3. Ectoderm
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5
Q

What is endoderm?

A

the inner layer that provides lining for digestive and respiratory tubes

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6
Q

What is mesoderm?

A

Middle layer where the bodys organs are found

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7
Q

What is the ectoderm?

A

Outer layer which gives rise to the skin

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8
Q

What are the functions of epithelium?

A
  • protect underlying tissues from injury
  • prevent bacterial invasion
  • prevent loss of fluid from underlying tissues
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9
Q

Describe the structure of epithelium?

A
  • cells closely packed together
  • intercellular stubsance (matrix) is minimal
  • cells lie on basement membrane
  • receive nourishment from underlying connective tissue
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10
Q

What are the different types of epithelium?

A
  • simple (single layer of cells)
  • stratified (several layers of cells)
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11
Q

What are the different types of simple epithelium ?

A
  • squamous
  • cuboidal
  • columnar
  • cilliated
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12
Q

Where can simple epithelium be found?

A

Usually on absorptive or secretory surfaces, not usually areas subject to stress

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13
Q

Describe simple squamous epithelium?

A
  • single layer of flattened cells
  • fit closely together forming a smooth inactive lining
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14
Q

Where can simple squamous epithelium be found?

A
  • blood vessels
  • alveoli of the lungs
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15
Q

What is the structure of simple cuboidal epithelium?

A
  • cube shaped cells
  • fit closely together lying on a basement membrane
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16
Q

What is the function of simple cuboidal epithelium?

A

involved in secretion, absorption & excretion

17
Q

What does simple cuboidal epithelium form?

A

Kidney tubules and some glands

18
Q

Describe simple columnar epithelium

A
  • single layer elongated cube shaped cells
  • height is greater than width
  • lies on basement membrane
19
Q

What is the function of simple columnar epithelium?

A
  • lines organs of alimentary tract and ducts of some glands
  • some absorb products of digestion, others secrete mucous
20
Q

What kind of specialised columnar epithelium secretes mucus?

A

Goblet cells

21
Q

What kids of epithelium are salivary glands?

A

Salivary glands are columnar epithelium

22
Q

What is the function of cilia on ciliated columnar epithelium?

A

On free surfaces of cells, cilia are fine hair like process have a beating action in one way to propel contents of a tube

23
Q

What is the function of ciliated epithelium?

A

moves particles or fluid over the epithelial surface

24
Q

What is a hemi- desmosome

A

specialised junctioning complexes which allows cells to join to eachother

25
Q

Where are hemi desmosomes found?

A
  • Within the cell membrane of epithelial cells
  • also found between epithelial cells and connective tissue cells
26
Q

Once cells have adhered to eachother what are they called

A

Desmosomes

27
Q

What do hemi desmosomes contain?

A

Tonofilbrils which cause thickening of the cell wall

28
Q

What is the primary function of stratified epithelium?

A

To protect underlying structures

29
Q

Describe the structure of stratified squamous epithelium?

A

Consists of different layers with the deepest layer continually multiplying and the cells of the surface shedding

30
Q

What is an example of stratified squamous epithelium

A

Skin & mucous membranes

31
Q

What are the. 2 types of stratified squamous epithelium?

A

Keratinised and non-keratinised

32
Q

What are the names of the layers in keratinised stratified squamous epithelium?

A
  • basal
  • prickle
  • granular
  • keratin
33
Q

Describe the basal layer of epithelium

A
  • single layer of cells at base which repeatedly divide
  • push cells up towards surface
  • finger like projections of connective tissue extend into epithelium
34
Q

What happens to the basal layer in areas of greater friction?

A

The basal layer folds to increase the surface area, forming rete ridges

35
Q

Describe the prickle cell layer

A
  • cells change from cuboidal to polyhedral
  • several layers of polyhedral cells present
  • prickles are formed by desmosomes
36
Q

Describe the granular layer of epithelium

A
  • 1-5 layers of flattened polyhedral cells
  • contains granules in cytoplasm
37
Q

Describe the keratin layer of epithelium?

A
  • outer layer of flattened cells remnants replaced by cells from below which have lost nucleus (sqaumes)
38
Q

Describe non-keratinised squamous epithelium

A
  • granular and keratin layer are absent
  • prickle layer cells become flattened
  • outer layer of cells cont. shed