Lecture 1

Question 1

Types of sweat glands

Answer 1

Apocrine, Eccrine

Question 2

Sweating

Answer 2

cholinergic response (regulated by certain neurotransmitters)

Question 3

Evaporation of sweat

Answer 3

causes goose bumps due to stimulation of contraction of the arrector pill muscle seen on the diagram

Question 4

Apocrine gland

Answer 4

associated with the hair follicles found in armpits, perineal region, and external ear canal.

Question 5

Apocine secretions

Answer 5

milky white and odorless. Upon exposure to cutaneous bacteria, it produces a pungent odor

Question 6

Sebaceous Gland

Answer 6

appendaged to the hair follicle: produces an oily substance called sebum whose function is unknown perhaps water repellancy?

Question 7

Sebum

Answer 7

contains liquid and solid phase, if out of balance it may contribute to acne

Question 8

Nail Plate

Answer 8

approximately 0.5mm-1.3mm thick. Includes dorsal nail plate, intermediate nail plate, adn ventral nail plate

Question 9

Nail Bed

Answer 9

Non cornified soft tissue underneath the nail plate, heavily vascularized. Extends from the lunlula to the hyponychium

Question 10

Nail Matrix

Answer 10

A thick layer of highly proliferative epithelial tissue responsible for nail plate. Lower cell layers contains melanocytes which likely confer the pigmentation to the nail plate. This layer is heavily vascularized.

Question 11

Nails

Answer 11

modified epidermis, contain 25 cell layers of flattened, dead keratinized cells fused into a hard slightly elastic plate. High in disulfide linkages

Question 12

Onychomycisis

Answer 12

nail fungal infections

Question 13

Onycholysis

Answer 13

nail loss

Question 14

Nail Psoriasis

Answer 14

pitting and white spots

Question 15

Infected eponychium

Answer 15

hang nail

Question 16

Dermal-epidermal junction

Answer 16

separates dermis from epidermis

Question 17

Dermis

Answer 17

separated into papillary dermis and reticular dermis

Question 18

Types of collagen in dermis

Answer 18

Type I - in reticular layer

Type III - in papillary layer

Question 19

Living cells

Answer 19

keratinocytes

Question 20

Dead cells

Answer 20

corneocytes

Question 21

epidermis

Answer 21

divided into 5 layers to be discuss next. main function is to replenish the stratum corneum

Question 22

Layers of epidermis

Answer 22

Basal, prickle, granular, clear, horny

Question 23

Melanocytes

Answer 23

large round cell with finger like projections called dendrites that reach out to keratinocytes. Found in basal layer. Produce dark pigment granules containing melanin which can be released into the keratinocyte where it clusters around the nucleus .

Question 24

Factors that influence color of skin

Answer 24

melanocytes, hemoglobin, and carotenes

Question 25

Langerhans cells

Answer 25

important for immunological reactions, can be found in other organs, and found mostly in prickle layer

Question 26

Merkel cells

Answer 26

in basal layer of epidermis, and connect to epithelial cells. involved in signaling to neuritt. Play active role in mechanotransduction.

Question 27

Length of time for keratinoytes to go from dermis to epidermis

Answer 27

28 days, takes 14 to go through stratum corneum

Question 28

How cells in basal layer are connected

Answer 28

Desmosomes. Match on each cell, connect via fibrils

Question 29

Basal Layer

Answer 29

contains keratinocytes that are actively dividing. Has capacity for DNA synthesis. Contain K5 and K14 keratins

Question 30

Spinous Layer/Prickle Layer

Answer 30

Keratinocytes begin process of differentiation - a process of regulated cell death and is controlled transcriptionally. K1 and K4 keratin is here. Produce loricrin

Question 31

Loricrin

Answer 31

Protein that becomes part of the cornified envelope.

Question 32

Prickle cell

Answer 32

named because of shape and filaments

Question 33

Granular Layer

Answer 33

Where final tailoring of protein synthesis occurs, and where the last stage of metabolic activity occurs. Has typical cells but apoptosis occurs.

Question 34

Fillagrin

Answer 34

the stacking protein that helps stack the keratin filament

Question 35

Stratum Lucidum/Clear Layer

Answer 35

Visible only in thickest skin, thin layer of translucent flattened cells, the cells have no nuclei (almost dead), their cytoplasm is filled with filaments

Question 36

Horney Layer/Stratum Corneum

Answer 36

Contains corneocytes. Uppermost layer, thickest on palms/soles (glabrous skin). Only contain proteins and lipids, and K1/K10 filaments

Question 37

Corneocytes

Answer 37

flat squames surrounded by multilamellar lipid layers; there are 15-20 layers of these in the S.C.

Question 38

Epidermal Proteins - Keratins

Answer 38

comprise 30% of the dry weight of visible epidermal cells and about 80% of the dry weight of S.C. Form coiled coil structure

Question 39

Filaggrin

Answer 39

Histidine rich protein, plays role in aggregating the keratin filaments in the stratum corneum. Made in the cell as a very large precursor molecule that consist of many chains joined by linker regions.

Question 40

Involucrin

Answer 40

A highly reactive, soluble, transglutaminase substrate protein present in keratinocytes. Helps in the formation of an insoluble envelope beneath the plasma membrane. It provides structural support to the cell, and resists invasion by micro-organism

Question 41

Cornified Cell Envelope

Answer 41

Forms around corneocyte. Provides structure and protection of the corneocyte. Comprimised of epidermal proteins - tranasglutaminase, lorigin, and involucin. Surrounded by covalently bonded lipid layer - ceramide and fatty acid.

Question 42

Key regulatory mechanisms of keratinocyte proliferation and differentiation

Answer 42

Nuclear hormone receptors, calcium second messenger signaling, immunomodulatory regulation, cytokines and growth factors.

Question 43

Calcium second messenger signaling

Answer 43

Keratinocytes grown in low calcium proliferate, grown in high calcium differentiate. There is a calcium gradient in epidermis, low in the basal proliferating layer and higher in the superficial layers.

Question 44

Inflammatory cytokines

Answer 44

Disruption of barrier with irritants like surfactants elicit production of two specific cytokines in the first phase. Act by binding to specific receptors in the cell membrane.

Question 45

Immunomodulary Cytokine action in skin

Answer 45

Antigen presenting cell binds to the T cell in skin. T cell interacting with antigen is either Th-1 or Th-2 depending on the disease/irritant mechanism. Th cells release cytokines associated with the disease state that act on mast cells or recruit appropriate white blood cells.