Skin

Question 1

7 Functions of the Skin

Answer 1

Barrier/Protection
Water/Temp Homeostasis
Peripheral Nervous System Receptors
Vitamin D Production
Excretion
Immunologic Functions
Endocrine

Question 2

Organization of the Skin

Answer 2

Epidermis (stratified squamous keratinized) avascular
Dermis
– Papillary Layer (LCT)
– Reticular Layer (DIRCT)
Hypodermis (adipose tissue/LCT)

Question 3

Blood Supply in Skin

Answer 3

Sub-papillary Plexus = papillary layer of dermis
Cutaneous Plexus = dermis
Subcutaneous Plexus = hypodermis

Question 4

Layers of the Epidermis

Answer 4

Stratum Corneum (apoptosed cells, cornified cell envelope)
Stratum Lucidum (apoptosis, water barrier, NOT in thin)
Stratum Granulosum (keratohyalin granules)
Stratum Spinosum (keratinocytes, keratin fibers 1/10)
Stratum Basale (mitotic active, keratin fibers 5/14)

Question 5

2 Types of Skin

Answer 5

Thick = 5 layers (palms of hands/soles of feet)
– no sebaceous glands, many sweat glands
– more sensory receptors
Thin = 4 layers [no lucidum]
– sebaceous glands, low sweat glands
– less sensory receptors

Question 6

Epidermis to Dermis Connection

Answer 6

Epidermal Ridge = pattern at top of epidermis
Dermal Papilla = dermis invaginates epidermis
Inter-papillary Peg = epidermis invaginates dermis

Hemi-desmosomes = connect keratinocytes to BM
Desmosomes = connect keratinocytes (Prickle Cells)
Tonofilaments = connect desmosomes

Question 7

Melanocytes

Answer 7

• found in stratum basale
• pigment produce cells
• dark nucleus with clear white halo

Question 8

Skin Pigmentation

Answer 8

1) Melanin accumulate in pre-melanosome
2) Melanosomes migrate to tip of melanocyte processes
3) Keratinocytes phagocytose the tips (melanosomes)
4) Melanosomes release melanin into cytoplasm
5) Melanin accumulate at UV side of nucleus

Question 9

Dark vs Light Pigmentation

Answer 9

type of melanin and rate of melanin breakdown

Question 10

Variation of Melanocytes

Answer 10

Lentigo Simplex = ↑ #of melanocytes
Ephelis (freckles) = ↑ melanin production
Melanocytic Nexus (moles) = growth of melanocytes

Question 11

Langerhans Cells

Answer 11

• antigen-presenting cells
• dendritic cells
• in stratum spinosum
• migrate to lymphoid organs
• clear cytoplasm, no prickles, dark nuclues

Question 12

Merkel Cells

Answer 12

• sensitive mechanoreceptors
• in stratum basale
• neurosecretory granules (with NTs)
• not visible in H&E stain