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Flashcards in ToB 2 Epithelia Deck (84)
1

Define epithelia:

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

2

Which 3 interior spaces in the body have epithelial linings, and are open to the exterior?

1) Gastrointestinal tract 2) Respiratory tract 3) Genitourinary tract

3

Which 5 interior spaces do not open to the exterior but have epithelial linings?

1) Peritoneum 2) Pleural sac 3) Pericardial sac 4) Blood vessels 5) Lymph vessels

4

What is the peritoneum?

The epithelial membrane lining the cavity of the abdomen and covering the abdominal organs.

5

What are pleural sacs?

The epithelial double membrane which covers a lung.

6

What is a pericardial sac?

The epithelial double membrane which encases the heart

7

What are the 3 embryonic germ layers which form the trilaminar embyonic disk?

1) Ectoderm 2) Mesoderm 3) Endoderm

8

Which embryonic germ layer creates skin?

Ectoderm

9

From which embryonic germ layer does the GI tract epithelium derive?

Endoderm

10

Which main 6 epithelia are derivatives of the embryonic mesoderm layer?

1) Blood vessels lining 2) Lymph vessels lining 3) Pericardial sac lining 4) Pleural sacs lining 5) Peritoneum lining 6) Epithelium of urogenital tract

11

From which embryonic germ layer does the respiratory tract derive?

Endoderm

12

What word describes an epithelium which is one cell thick?

Simple

13

What does 'compound epithelium' mean?

Epithelium consists of more than one layer of cells.

14

Define pseudostratified epithelium:

An epithelium which is one cell thick, but gives the appearance of a stratified epithelium due to the position of the cell nuclei.

15

What is meant if a cell is described as 'squamous'?

Very thin and flat, such that the cells nucleus creates a bump in the membrane

16

What type of cells make up the basement membrane?

The basement membrane is a non-cellular layer

17

Define basement membrane:

A thin, delicate non-cellular membrane which separates an epithelium from underlying tissue.

18

How is the basement membrane sometimes thicker than usual?

Reticular cells may produce type III collagen, which thickens the basement membrane

19

What is the name of the membrane to which epithelial cells adhere?

Basement membrane

20

Which part of an epithelial membrane acts as a cellular and molecular filter?

Basement membrane

21

What is the (often used) Latin name for the basement membrane?

Basal lamina

22

What name is given to the simple squamous epithelium lining of all vascular elements?

Endothelium

23

What is a mesothelium?

The simple squamous epithelia which line the pericardial sac, pleural sacs and the peritoneum.

24

Describe the upper respiratory tract epithelia:

Ciliated pseudostratified epithelia

25

Describe the epithelium lining the loop of Henle:

Simple squamous epithelia

26

Give 2 examples of simple squamous epithelia in the kidney:

1) Lining of the loop of Henle 2) Bowman's capsule

27

What are the 4 main functions of a simple squamous epithelium?

1) Barrier 2) Gas exchange 3) Active transport (pinocytosis) 4) Lubrication

28

How would you describe an epithelium which is one cell thick, where each cell is (roughly) as tall as it is wide?

Simple cuboidal epithelium

29

What type of cells line the thyroid gland follicles?

Simple cuboidal epithelia

30

What type of cells line the collecting ducts of the kidney?

Simple cuboidal epithelia

31

Which hormone do the epithelial cells lining the collecting duct of the kidney respond to?

Anti-diuretic hormone (ADH)

32

What type of epithelia line the surface of an ovary?

Simple cuboidal epithelia

33

Small ducts of many exocrine glands are lined by what type of epithelia?

Simple cuboidal epithelia

34

What 2 functions must the epithelium of a kidney tubule have?

1) Absorption 2) Secretion

35

What type of epithelial cell line the Crypts of Liebekuhn in the intestine?

Simple columnar epithelia

36

In what position do you usually find the nuclei of columnar cells?

In the basal half of the cell (near basement membrane)

37

What type of cells line the gall bladder?

Simple columnar epithelia

38

What is the main function of the gall bladder epithelial cells?

Absorb water and electrolytes from bile (produced by liver)

39

What is meant by a striated epithelial cell?

The basal membrane of the cell is extensively infolded

40

Where can you find a striated simple columnar epithelium?

In part of the parotid salivary gland

41

What type of cells line the fallopian tube of the uterus?

Simple columnar epithelia (sometimes ciliated)

42

On a cell with microvilli, approximately how many microvilli are found on each cell?

~ 1000 microvilli/cell

43

What type of protein can bind adjacent plasma membranes tightly, restricting certain proteins to the apical membrane?

Occludin

44

What type of cell fusion is created by the 'zonula occludens'?

Tight junctions by the protein 'occludin'

45

What type of epithelial cell line the villi of the small intestine?

Simple columnar epithelial cells

46

What types of cells line the stomach, gastric glands, small intestine and colon?

Simple columnar epithelial cells

47

What are the 3 main functions of a simple columnar epithelial cell?

1) Lubrication 2) Absorption 3) Secretion

48

What is meant when an epithelium is described as 'simple'?

Every cell makes contact with the basement membrane

49

Describe the epithelial cells which line the upper respiratory tract:

Pseudostratified ciliated columnar epithelial cells

50

How quick do the motile cilia present in the upper respiratory tract beat?

12 beats/sec

51

Define epididymis:

A highly convoluted duct behind the testis, along which sperm passes to the vas deferens

52

What is the 'vas deferens'?

Duct which transports sperm from the testicle to the urethra

53

Approximately how long is the epididymis?

~4-6m long

54

What type of epithelial cells line the epididymis?

Pseudostratified epithelium, which contain stereocilia

55

What is the function of the principal cells of the epididymus epithelium?

Absorb fluid Secrete substances to promote sperm maturation Phagocytose degenerate sperm

56

How would you describe a stratified epithelium in which the cells have a different shape at the top, to the cells at the bottom?

The description always applies to the outermost layer of the epithelia.

57

What type of epithelial cells line the vagina?

Non-keratinised stratified squamous epithelial cells

58

What is present in the vagina to maintain the suitably low pH?

Lactobacilli, which produce lactic acid

59

Why does the oesophagus have a stratified epithelium?

For lubrication and protection against abrasion

60

Define epiglottis:

A flap of cartilage behind the root of the tongue, which is depressed during swallowing to cover the trachea.

61

Describe the epithelium which lines the oesophagus side of the epiglottis:

Stratified squamous non-keratinised epithelium

62

Describe the epithelium which lines the trachea side of the epiglottis:

Pseudostratified epithelium

63

What is the name of the outer surface of the eye?

Cornea of the eye

64

Which embryonic germ layer creates the cornea of the eye?

Ectoderm

65

What is situated directly behind the cornea of the eye?

Anterior chamber

66

What type of epithelial cells line the outer surface of the cornea (of the eye)?

Non- keratinised stratified squamous epithelial cells

67

Name 7 locations which have non-keratinised stratified squamous epithelial cells:

1) Oral cavity 2) Oesophagus 3) Larynx 4) Vagina 5) Outer surface of cornea 6) Part of anal canal 7) Inner surface of eyelid

68

What are the 2 main functions of a non-keratinised stratified squamous epithelium?

1) Prevent water loss but stay moist 2) Protect against abrasion

69

What is meant by a 'keratinised stratified epithelium'?

An epithelium whose outer layer is made up of dead cells with no nuclei.

70

Where on the body can you find a thicker layer of dead keratinised epidermal cells?

Palms and soles of feet.

71

What are the 4 main functions of a keratinised stratified squamous epithelium?

1) Protect against abrasion and/or physical trauma

2) Prevent water loss

3) Prevents ingress of microbes

4) Shields against UV light damage

72

What is meant by a 'transitional epithelium'?

An epithelium in which the cells vary in shape, from cubodal/columnar/squamous.

73

Why would it benefit a tissue to have a transitional epithelium?

If the tissue must often stretch and relax, a transitional epithelium allows the tissue to be covered and protected at all times.

74

What type of epithelium is present lining the ureter?

Transitional epithelia

75

What type of epithelia is present lining the bladder?

Transitional epithelia

76

What are the 2 main functions of a transitional epithelium?

1) Distensibility

2) Protection against toxic chemicals

77

Why do different epithelia have different rates of renewal?

It depends on the location and function of the epithelia.

78

What is the average turnover time for a skin epithelial cell? (from cell division to death)

~ 28 days

79

What is the average turnover time for an epithelial cell present in the base of the crypts of the small intestine?

~ 4-6 days

80

What is the main difference between microvilli and stereocilia?

Stereocilia are much longer than microvilli

81

Where are stereocilia found in the body, and what is their (presumed) function?

On the epithelium lining the epididymis, thought to increase surface area.

82

What are the 3 junctional complexes that a cell membrane can form, for lateral adhesion to other cells?

1) Desmosomes

2) zonulae occulentes

3) zonulae adherentes

83

What can the cell membrane form to allow lateral cell-to-cell communication?

Gap junctions

84

What does the basal cell membrane form to allow adhesion to the basement membrane?

Hemidesmosomes