Lecture 19 - Integument

Question 1

What are the layers of the integument?

L19 S5

Answer 1

Epidermis

Basement membrane

Dermis

Subcutaneous tissue

Question 2

What are the components of the epidermal ridges?

L19 S6-7

Answer 2

Primary dermal ridge

Interpapillary peg

Secondary dermal ridges

Dermal papillae

Question 3

Thick skin/thin skin

L19 S9

Answer 3

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Question 4

What are the different layers of the epidermis?

L19 S10

Answer 4

Stratum basale

Stratum spinous

Stratum granulosum

Stratum lucidum

Stratum corneum

Question 5

What are the characteristics of the stratum basale?

L19 S13

Answer 5

• columnar to high cuboidal
• single layer of cells
• contain keratins 5 and 14
• high mitotic activity stem cells which differentiate into keratinocytes

Question 6

What are the characteristics of the stratum spinosum?

L19 S14

Answer 6

• polyhedral-shaped cells (prickle cells)
• contains keratins 1 and 10
• keratohylain granules
• membrane coating granules (lamellar bodies)
• tonofibrils

Question 7

What are the characteristics of the stratum granulosum?

L19 S17

Answer 7

• contains keratins 2e and 9
• flattened nucleated keratinocytes
• keratohyalin aggregates
• membrane-coating granules (lamellar bodies)

Question 8

What are the characteristics of the stratum lucidium?

L19 S18

Answer 8

• contains eleiden
• flat keratinocytes lacking nuclei and organelles
• only present in thick skin

Question 9

What are the characteristics of the stratum corneum?

L19 S18

Answer 9

• multiple layer of varying thickness (5-50)
• enucleated, flattened, dead keratinocytes
• cytoplasm replaced by keratin crosslinked with filaggrin
• cornified cell envelope (lipid layer linked to involucrine)

Question 10

What are the characteristics of the dermis?

L19 S25-26

Answer 10

• dense irregular connective CT
• supports epidermis

Papillary layer:

• loose CT
• separated from skin by basal lamina
• abundant capillaries

Reticular layer:

• dense regular CT
• fibrocytes, macrophages, adipocytes

Question 11

What are Langerhans cells?

L19 S28

Answer 11

• dendritic, antigen producing cells derived from monocytes
• migrate from lymph vessels
• found primarily in the stratum spinosum
• contain Birbeck granules

Question 12

What are Merkel cells?

L19 S29

Answer 12

• mechanoreceptors
• typically found in stratum spinosum
• contain catecholamine-like granules

Question 13

What are melanocytes?

L19 S30

Answer 13

• do not form desomsomes and are therefore mobile

- create melanin granules which are injected into keratinocytes

Question 14

What are the characteristics of sebaceous glands?

L19 S34

Answer 14

• holocrine glands
• branched, acinar gland
• located in all skin except palms and soles
• produce sebum which is released into hair folicles (oil)

Question 15

What are the types of sudoriferous glands?

L19 S36

Answer 15

Merocrine gland:

• coiled, simple tubular glands
• apical cells secrete glycoproteins
• basal cells secrete water and electrolytes
• myoepithelium

Apocrine:

• located in labia majora, areola, axilla, and anal regions
• secretions are thicker
• opens into typically hairless hair follicles
• inactive until puberty
• adrenergic activation

Question 16

What are the components of a hair folicle?

L19 S40

Answer 16

Hair bulb:
-expanded part of hair follicle

External root sheath

Internal root sheath

Hair shaft:
-medulla, cortex, and cuticle

Arrector pile muscles and sebaceous glands are associated