Integument I Flashcards Preview

A. White- Histology > Integument I > Flashcards

Flashcards in Integument I Deck (64):
1

What is the general organization of the integument?

epidermis, basement membrane, dermis, subcutaneous tissue

2

What are some synonyms for subcutaneous tissue?

SubQ, superficial fascia, hypodermis

3

What are the types of epidermal ridges?

primary dermal ridge, interpapillary peg, secondary dermal ridges, dermal papillae

4

Describe primary dermal ridges

• Related to finger prints • Found everywhere except forehead, external ear, perineum, and scrotum • Formed during 3rd to 4th months of fetal life • Subdivided into two secondary dermal ridges by interpapillary peg

5

What is the interpapillary peg?

Downward growth of epidermis along crest

6

describe secondary dermal ridges

• Occur in double rows, branched • Thin collagenous, reticular, and elastic fibers

7

What are dermal papillae

Upward projections from each secondary dermal ridge

8

List the integument functions

• Protection from mechanical injury • Prevents dessication • Protects against foreign substances and microorganisms • Protects against UV radiation • Thermoregulation • Regulation of blood pressure (via dermal capillary network) • Excretion of metabolic waste products • Synthesis of provitamin D

9

Describe thick skin

• Occurs only on palms and soles and is hairless • Epidermis varies from 0.4 to 0.6 mm thick. • Displays all five epidermal layers

10

Describe thin skin

• Occurs over rest of body • Epidermis varies from 75 to 150 μmm thick. • Thinnest thin skin is on eyelids • Thickest thin skin is on back • Thicker on extensor surfaces than flexor surfaces • Epidermal layers less distinct and lacking stratum lucidum

11

What are the layers of the stratified squamous epithelium of the epidermis?

• Stratum basale (germinativum) • Stratum spinosum • Stratum granulosum: • Stratum lucidum • Stratum corneum

12

Which is the deepest layer of the epidermis?

stratum basale

13

Which layer of the epidermis is represented by only a few cells in thin skin?

stratum granulosum

14

Which layer of the epidermis is absent in thin skin?

stratum lucidum

15

Which layer of the epidermis is most superficial?

stratum corneum

16

Describe stratum basale.

(germinativum) • Deepest • Columnar to high cuboidal keratinocytes • Keratins 5 and 14 (low-molecular weight keratins) • Single layer of cells • Held together by desmosomes • Hemidesmosomes hold layer to basal lamina • High mitotic activity: • Mitotic activity produces stem cells differentiating keratinocytes. • Affected by chemotherapeutic and radiation treatments

17

Describe stratum spinosum

• Polyhedral-shaped cells (prickle cells) • Keratins 1 and 10 (high molecular weight keratins) • Keratohyalin granules develop • Membrane-coating granules first appear: • Lamellar bodies • Contain lipid, carbohydrate, and hydrolytic enzymes • Tonofibrils • Form intercellular bridges

18

Describe stratum granulosum

• Multilayered • Keratins 2e and 9 • Flattened nucleated keratinocytes • Keratohyalin aggregates: • Fillagrin induces cross-linkage of keratin filaments by disulfide bonds • No limiting membrane • Membrane-coating granules (lamellar bodies) • Acylglucosylceramide → intercellular spaces • Tonofilaments

19

Describe stratum lucidum

• Flat keratinocytes lacking nuclei and organelles • Only found in thick skin • Contains eleiden

20

Describe stratum corneum

• Multilayered (5-50 layers) • Thicker in thick skin • Enucleated, flattened, dead keratinocytes • Cytoplasm replaced by keratin • Cytoplasm contains: • Keratin cross-linked with filaggrin • → cornified cell envelope

21

List and describe the layers of the cornified cell envelope.

• Extracellular: • Multi-lamellar lipid layer covalently linked to involucrine • Intracellular: • Involucrine • Small proline-rich proteins • Loricrin • Fillagrin and keratin complexes

22

What are the characteristics of the dermis?

• Dense fibrous irregular connective tissue layer beneath epidermis • Derived from embryonic mesoderm • Induces development of epidermis and epidermal derivatives • Supports epidermis

23

What are the characteristics of the hypodermis?

• Loose connective tissue that underlies dermis • Corresponds to superficial fascia of gross anatomy • Technically not part of skin • May contain fat cells that can form a thick layer called the panniculus adiposus.

24

List and describe the two layers of the dermis.

• Papillary layer (closest to epidermis): • Loose CT • Separated from epidermis by basal lamina • Network of fine elastic fibers and abundant capillaries • Reticular layer • Dense irregular CT • Includes fibrocytes, macrophages, and adipocytes

25

What are the cells of the integument?

• Keratinocytes • Langerhans cells • Merkel cells • Melanocytes

26

Describe Merkel cells.

• Mechanoreceptors • May also act as diffuse neuroendocrine cells • Usually in stratum germinativum • Contain catecholamine-like granules

27

Describe Langerhans cells.

• = dendritic cells • From monocytes • Antigen-presenting cells • Primarily in stratum spinosum • Migrate from epidermis to lymph nodes • Birbeck granules

28

Describe Melanocytes.

• Derived from melanoblasts • Do not form desmosome attachments in epidermis • Inject melanin granules into keratinocytes • Pathway for melanin formation

29

What is the pathway for melanin formation?

Tyrosine → 3,4-dihydroxyphenylalanine (DOPA) → dopaquinone → melanin

30

What does melanin formation require?

tyrosinase

31

Explain the embryonic origins of the epidermis.

Epidermis starts as a single layer of ectodermal cells. • Divide during sixth week to form: • Periderm • Sloughs off to form vernix caseosa • Inner cuboidal germinal layer: • continues to proliferate to form adult layers of the epidermis and derivatives: • 10 weeks: fingernails • 12 weeks: hair buds and toenails

32

Explain the embryonic origins of the dermis.

Dermis is derived from mesoderm

33

What is A?

primary epidermal ridge

34

What is B?

interpapillary peg

35

What is C?

dermal papilla

36

What is D?

secondary dermal ridges

37

What is E?

primary dermal ridge

38

What is F?

epidermis

39

What is G?

dermis

40

What is H?

hypodermis (subcutaneous layer)

41

What is A?

stratum corneum

42

What is B?

stratum granulosum

43

What is C?

stratum spinosum

44

What is D?

stratum basale

45

What is E?

papillary layer of dermis

46

What is F?

reticular layer of dermis

47

What is A?

stratum corneum

48

What is B?

stratum lucidum

49

What is C?

stratum granulosum

50

What is D?

stratum spinosum

51

What is E?

stratum basale

52

What is F?

stratum of malpighi

53

What is pictured?

tonofilaments in stratum spinosum

54

What is indicated by the star?

melanocytes

55

What is pictured?

thin skin (scalp)

56

What is pictured?

thick skin

57

What is A?

stratum corneum

58

What is B?

stratum lucidum

59

What is C?

stratum granulosum

60

What is D?

stratum spinosum

61

What is E?

stratum basale

62

What is F?

papillary layer

63

What is G?

reticular layer

64

What is pictured?

integument, dermis