8, 12 - Skin I And Ii - Kretzer

Front 1

Six Functions of Skin:

Back 1

1) Barrier
2) Sensory Organ
3) Thermoregulation
4) UV Protection
5) Immune (SALT: Skin Associated Lymphoid Tissue)
6) Sexuality (Apocrine and sebaceous glands in dermis secrete pheromones)

Front 2

Three Layers of Skin:

Back 2

1) Epidermis: epithelial layer resting on basement membrane
A) Thick skin—non hairy with very thick epidermis
B) Thin skin—hairy with thin epidermis
2) Dermis: papilla project into epidermis to keep layers from sliding past each other,
capillary beds, Meissner’s corpuscles
A) Lower dermis—dense irregular connective tissue
B) Upper dermis—loose connective tissue housing ecrine, apocrine and
sebaceous glands
3) Hypodermis: dense irregular connective tissue with fat, Pacinian corpuscles

Front 3

Three ways skin acts as barrier

Back 3

1) Barrier to infection (via keratinocyte layer)

2) Barrier to water loss (via extracellular lipid layer in stratum granulosum)

3) barrier to friction (via keratin layer and the dermal papillae and epidermal pegs)

Front 4

Stratum Basale

Back 4

Contacts basement membrane, consists of keratinocytes=STEM CELLS, mitotically active, desmosomes hold keratinocytes together, hemidesmosomes and focal contacts hold keratinocytes to basement membrane

Front 5

What senses touch and pressure in skin?

Back 5

nerve net around hair follicles

Merkel cells

Meissner's corpuscles

Pacinian corpuscles

Front 6

Stratum Spinosum

Back 6

A. Tons of DESMOSOMES for strong cohesion and barrier against friction, gives characteristic spiny appearance B. Filaggrin bundles intermediate filaments (cytokeratin—called tonofilaments in skin) into tonofibrils C. Mitotic in that some cells may divide to produce more spinosum cells

Front 7

Five Layers of the Epidermis:

Back 7

1) Stratum Basale

2) Stratum Spinosum

3) Stratum Granulosum

4) Stratum Lucidum

5) Stratum Corneum

Front 8

Stratum granulosum

Back 8

WATER BARRIER through Odland bodies containing phospholipids of skin’s water barrier, keratinohyalin formed into characteristic GRANULES of this layer

Front 9

SALT

Back 9

Skin Associated Lymphoid Tissue - includes:

keratinocytes, which secrete factors important for the maturation of T-lymphocytes

Langerhans cells - defend body from bacterial invaders

Front 10

Stratum lucidum

Back 10

Cannot see histologically, LYSOZYMES BURST, nucleus and organelles dissolve, keratohyalin cements tonofibril bundles together, desmosomes still intact

Front 11

Stratum Corneum

Back 11

layer of DEAD keratinocytes A. stratum compactum—still desmosomes B. stratum disjunctum—upper most layer, no more desmosomes, desqamation (stem cell to desquamation = 30 days)

Front 12

Types of Secretion:

Back 12

1) Merocrine: exocytosis into extracellular space
2) Apocrine: apical portion of cell ruptures but cell anneals and lives
3) Holocrine: cell death in secretion

Front 13

What does the immune function of skin include?

Back 13

SALT and Langerhans cells

Front 14

Three Glands in Skin:

Back 14

1) Sebaceous glands: acinar, NO lumen, secrete lipid pheromones by holocrine
secretion, no myoepithelial cells, associate with every hair follicle and also
without hair follicles in lips, glans penis, glans clitoris, areola of breasts, glands
develop at puberty
2) Apocrine glands: coiled tubular (simple cuboidal or columnar), LARGE lumen,
secrete proteinaceous pheromones by merocrine secretion, stratified cuboidal
duct, myoepithelial cells, always associated with hair follicles but are only in
circumanal region, genitalia, areola of breasts, axillae, develop at puberty
3) Ecrine glands: coiled tubular, SMALL lumen, light cells=ion pumpers, dark
cells=secrete mucous by merocrine secretion, stratified cuboidal duct (basophilic),
myoepithelial cells, important for thermoregulation

Front 15

For sexuality, what do apocrine and sebaceous glands secrete?

Back 15

Apocrine - proteins

Sebacious - lipids

Front 16

Three Non-keratinocytes in Epidermis:

Back 16

1) Merkel cell: sensory function
2) Melanocyte: NEURAL CREST ORIGIN!!, vimentin positive
3) Langerhans cell: MONOCYTE ORIGIN!!, vimentin positive

Front 17

Pathology of Epidermis

Back 17

Pemphigus

Bullous pemphigus

Psoriasis

Squamous cell carcinoma

Basal cell carcinoma

Melanoma

Front 18

Pathology of Epidermis: Pemphigus

Back 18

loss of adhesion between cells

Front 19

Pathology of Epidermis: Bullous pemphigus

Back 19

loss of adhesion with basement membrane

Front 20

Pathology of Epidermis: Psoriasis

Back 20

thickening of skin and subsequent cracking down to dermis

Front 21

Pathology of Epidermis: Basal cell carcinoma

Back 21

neither are very invasive due to cell-cell junctions

Front 22

Pathology of Epidermis: Melanoma

Back 22

extremely invasive because no cell-cell contacts