Epithelial tissue Flashcards Preview

Z OLD Tissues of the Body > Epithelial tissue > Flashcards

Flashcards in Epithelial tissue Deck (138):
1

What is epithelia?

Sheets of contiguous cells, of varied embryonic origin, that cover the external surface of the body, and line the internal surfaces

2

What is the exterior epithelial lining?

Skin

3

What kind of epithelium is skin?

Keratinised, stratified, squamous

4

Is skin living or dead?

Outermost layer is dead, living underneath

5

Give 3 interior epithelial surfaces that open to the exterior

- Gastrointestinal 
- Respiratory tract
- Genitourinary tract

6

Where does the GI tract start and end?

Mouth to anus

7

Where does the respiratory tract start and end?

Nasal cavity to alveoli

8

Give 5 epithelial surfaces that don’t open to the exterior

- Pericardial sac
- Pleural sacs 
- Peritoneum 
- Blood vessels
- Lymphatic vessels

9

What is the pericardial sac?

Sac that contains heart

10

What is the pleural sac?

Very thin sac that contains the lungs

11

What does the peritoneum contain?

Most of the gut contents

12

What do the blood vessels constitute?

The entire cardiovascular system

13

What is the epithelium a derivative of?

The 3 germ layers of the embryo

14

Describe the structure of the trilaminar embryonic disc

3 layers with motor cord in middle

15

What are the 3 layers in the trilaminar disc?

#NAME?

16

What epithelium is derived from the ectoderm?

- Epidermis of skin 
- Corneal epithelium of skin

17

What epithelium is derived from the mesoderm?

#NAME?

18

What epithelium is derived from the ectoderm?

#NAME?

19

What are the two main classifications of epithelia?

#NAME?

20

What is meant by simple epithelium?

One cell layer thick

21

What is meant by stratified/compound?

More than 1 cell layer thick

22

What does all epithelium have?

A basal surface on the basement membrane

23

What is the basement membrane?

A thin, flexible, acellular layer that lies between epithelial cells and subtending connective tissue

24

What is meant by acellular?

Not made up of cells

25

What is the part of the basement membrane closest to the epithelium

Basal lamina

26

What lies down the basement membrane?

Epithelial cells

27

How is the thickness of the basement membrane augmented?

By variably thick layer of reticular fibrils, elaborated by type III connective tissue

28

what are reticular fibrils?

Type III collagen

29

What is the purpose of the basement membrane?

- Serves as a strong, flexible layer to which the epithelial cells adhere. 
- Cellular and molecular filter

30

What is basement membrane made up of?

Not cells, just fibre type connective tissue

31

How is the basement membrane clinically relevant in cancer?

The degree to which the malignant cells permeate the basement membrane is highly relevant to prognosis- better prognosis if the neoplasm is not through the basement membrane

32

Describe the structure of simple squamous epithelium

#NAME?

33

What is endothelium?

Simple squamous lining of all vascular elements (arterial, venous, capillary and lymphatics)

34

What is the function of endothelium?

- Exchange gases and nutrients 
- Allow certain blood cells to enter tissues
- Regulate platelet coagulation

35

Where is simple squamous epithelium located?

- Lining of blood and lymph vessels
- Lining of body cavities- pericardium, pleura, peritoneum 
- Pulmonary alveoli
- Bowman’s capsule and Loop of Henle in kidney
- Inner and middle ear

36

What is simple squamous epithelium called when it’s lining body cavities?

Mesothelium

37

What are the functions of simple squamous epithelium?

#NAME?

38

Where does simple squamous epithelium have a lubricating function?

#NAME?

39

Where does simple squamous epithelium have a gas exchange function?

Pulmonary alveoli

40

Where does the simple squamous epithelium have a barrier role?

In the Bowman’s capsule

41

Where does the simple squamous have a role in active transport by pinocytosis?

Mesothelium and endothelium

42

What shape are the cells of simple cuboidal epithelium?

Polygonal, but the cells are about as high as they are wide

43

Where is simple cuboidal epithelium found?

#NAME?

44

Are all ducts lined with simple cuboidal epithelium?

No, depends on location and size

45

What is the surface of the ovary called?

Germinal epithelium

46

What are the functions of simple cuboidal epithelium?

- Absorption and conduit 
- Absorption and secretion 
- Barrier/covering
- Hormone synthesis, storage and metabolism

47

Where does simple cuboidal epithelium have a absorption and conduit function?

Exocrine glands

48

Where does simple cuboidal epithelium have an absorption and secretion function?

Kidney tubules

49

Where does simple cuboidal epithelium have a barrier function?

Ovary

50

Where does simple cuboidal epithelium have a hormonal function?

Thyroid

51

What shape are simple columnar epithelium?

Taller than they are wide

52

How can simple columnar epithelium sometimes appear under microscopes due to the cut?

Stratified

53

What features can simple columnar epithelium found?

#NAME?

54

What is the purpose of simple columnar with microvilli?

Increase the surface area

55

Where are junctional complexes?

In apical portion of adjoining cells

56

What is a junctional complex?

A particularly tight junction

57

What is the purpose of junctional complexes?

Prevents gut contents penetrating between cells and gaining access to the body

58

What is the advantage of junctional complexes?

They give very tight control of what goes into the body

59

What does occludin do?

Binds adjacent plasma membranes tightly together is apical portions of some epithelia

60

Can membrane proteins bypass the junctional complex?

No

61

What are junctional complexes also known as?

Zonula occludens

62

What does the zonula occludens allow the cell to do?

Restrict certain proteins to apical (free) surface, and restrict others to the lateral and basal surface.

63

What does the junctional complex separate?

The luminal space from the intercellular space

64

Describe the passage of fluid from the intestinal lumen

Intestinal lumen →  cell →  intercellular space →  basement membrane →  connective tissue

65

What are villi?

Projections into the small intestine

66

What are villi lined by?

Simple columnar epithelium with microvilli

67

What is the purpose of the villi?

Increase SA

68

What do villus do?

Absorb nutrients from the small intestine

69

What cells do simple columnar often have?

Goblet cells

70

Where do goblet cells run from?

Basement membrane →  surface

71

What do goblet cells do?

Produce mucus

72

Where is simple columnar epithelium found?

- Stomach and gastric glands 
- Small intestine and colon 
- Gall bladder
- Large ducts of some exocrine cells 
- Oviducts
- Uterus 
- Ductuli efferents of testis

73

What are the functions of simple columnar epithelium?

- Absorption 
- Secretion 
- Lubrication
- Transport

74

Where does simple columnar epithelium have an absorption function?

- Small intestine and colon 
- Gall bladder

75

Where does simple columnar epithelium have a secretion function?

- Stomach lining
- Gastric glands
- Small intestine 
- Colon

76

Where does simple columnar epithelium have a lubrication function?

#NAME?

77

Where does simple columnar epithelium have a transport function?

Oviduct

78

Why is pseudostratified epithelium so named?

Because it looks like its stratified, but simple because every cell makes contact with the basement membrane

79

What happens to nuclei in pseudostratified epithelium?

They end up in different places

80

How does the basement membrane differ in pseudostratified epithelium?

It is thicker

81

What features can pseudostratified epithelium have?

- Can have cilia and stereocilia 
- Can contain goblet cells

82

Where does pseudostratified epithelium have cilia?

Trachea

83

Where does pseudostratified epithelium have stereocilia?

Testes

84

Where is pseudostratified epithelium found?

- Lining of nasal cavity, trachea and bronchi
- Epididymis and ductus deferens 
- Auditory tubes and part of lymphatic cavity 
- Lacrimal sac
- Large excretory ducts

85

What are functions of pseudostratified epithelium?

- Secretion and conduit 
- Absorption 
- Mucus secretion 
- Particle trapping and removal

86

Where does pseudostratified epithelium have a secretion and conduit function?

#NAME?

87

Where does pseudostratified epithelium have an absorption function?

Epididymis

88

Where does pseudostratified epithelium have a particle trapping and removal function?

Respiratory tract

89

In stratified epithelium, what is the name based on?

The outermost cell- next to the lumen

90

In stratified epithelium, which cell is attached to the basement membrane?

Only basal cell layer

91

What kind of epithelium is found in the vagina?

Stratified squamous non-keratinized epithelium

92

What are vagina cells rich in?

Glycogen

93

Why is it important that vagina cells are rich in glycogen?

Substrate for numerous lactobacilli, which produce lactic acid, maintaining a low vaginal pH

94

What do the vaginal cells cause in absence of hormonal stimulation?

Atrophy

95

What kind of epithelium is found in the oesophagus?

Stratified squamous non-keratinised epithelium

96

What is the role of the epithelium in the oesophagus?

Protects from abrasion

97

How is the oesophagus need protection from abrasion?

When eating, the outer cells slough off, but are replaced by mitosis, which is occurring in the basal layer, with cells differentiate as they move upwards.

98

What epithelium lines epiglottis?

#NAME?

99

What does the epiglottis do?

Stops food going into lungs on swallowing, and then springs back to allow for breathing

100

What is the epiglottis adapted for?

Protection against abrasion

101

What epithelium is on the outermost layer of the eye?

Stratified squamous

102

What is the epithelium on the outermost layer of the eye adapted for?

To withstand the constant abrasion of opening and closing the eye

103

In what locations is stratified squamous epithelium found?

- Oral cavity 
- Oesophagus 
- Larynx 
- Vagina 
- Part of anal canal 
- Surface of cornea
- Inner surface of eyelid

104

What are the functions of stratified squamous epithelium?

#NAME?

105

What is special about keratinised stratified squamous epithelium?

Outermost cells are dead and have lost their nuclei

106

What does keratinised stratified squamous epithelium line?

Skin

107

Where is the epidermis thicker?

Sole of foot and palms of hands

108

What is often true of the margin between connective tissue and epidermis?

It’s quite convoluted

109

What is meant by the border being convoluted?

Dermal papilla go up

110

What is the purpose of the convoluted border?

The skin doesn’t slide off as easily, so less likely to blister

111

Where is keratinised stratified squamous epithelium located?

#NAME?

112

When does the oral cavity begin to keratinise?

If someone mouth breaths a lot

113

What is the function of keratinised stratified squamous epithelium?

- Protection against abrasion and physical trauma 
- Prevents water loss
- Prevents ingress of microbes
- Shields against UV light damage

114

How is the skin protected from UV damage?

Melanosomes in the skin line up on the outer surface of the nuclei, to try and protect the DNA from UV damage

115

Describe transitional epithelium

Surface cells can vary in shape, from columnar/cuboidal to flattened. It looks different depending on wether or not its stretched

116

What is transitional epithelium adapted to do?

Stretch

117

Why is transitional epithelium adapted to stretch?

Because it lines the urinary system, and so needs to allow for extension of the bladder

118

How can transitional epithelium often be recognised on micrographs?

By slightly bowed appearance of outermost cells in stretched state

119

Where is transitional epithelium found?

#NAME?

120

What is the function of transitional epithelium?

#NAME?

121

Is a epithelial cells rate of renewal variable or constant?

Pretty constant

122

What does the turnover rate for each epithelial cell type depend on?

- Location 
- Function

123

When is the renewal time frame for epithelium not constant?

When injury leads to acceleration

124

What is the time frame for renewal of epidermis?

From cell division in basal layer to being sloughed off, ~28 days

125

What happens to a epidermis cell in its lifetime?

Differentiation, migration to exterior, keratinisation and death

126

How often are cells lining the small intestine replaced?

Every 4-6 cells

127

What replaces cells in the lining of the small intestine?

Regenerative cells in the base of crypts

128

What happens to some epithelial cells once adulthood is reached?

They cease to be renewed

129

What can happen to cells that cease to be renewed once they reach adulthood?

The triggering of cell proliferation

130

What does cell proliferation do?

Replace lost cells

131

Why might cells be lost?

#NAME?

132

Give 2 epithelial cells that have different types of surface specialisation?

#NAME?

133

What are microvilli?

Cytoplasmic apical extensions

134

What is the purpose of microvilli?

They increase the SA for selective absorption of intestinal contents

135

What do microvilli have inside them?

Little actin threads going into them

136

What is the purpose of the actin threads?

Give them shape

137

What are stereocilia?

Very long microvilli

138

Where are sterocilia found?

Extending from surface of epididymal