2/3/16 - Exam 3

Question 1

Fitzpatrick Skin Types

Answer 1

I-VI, check if need to know specifics

Question 2

Eumelanin

Answer 2

black to brown pigment

Question 3

Pheomelanin

Answer 3

yellow to red-brown pigment

Question 4

Langerhans cells

Answer 4

epidermally located, implicated in immune function

• Found in small numbers in all of the epidermal layers
• Dendritic cells in the epidermis derived from a bone marrow stem cell
• Participate in cell-mediated immune reactions by processing and presenting antigens (circulate
back and forth between skin and lymph nodes)

Question 5

Keratinocytes do what -

Answer 5

Vitamin D synthesis, Water homeostasis (w/ Adnexa: Eccrine glands)

Question 6

Adnexa: Eccrine glands do what -

Answer 6

Water homeostasis (w/ keratinocytes) and thermoregulation (w/ blood vessels). These are the sweat glands as opposed to the sebaceous glands

Question 7

Dermis is -

Answer 7

an underlying connective tissue layer, which includes:
• the papillary layer (loose connective tissue) lies immediately under the epidermis
• a deeper reticular layer (dense connective tissue)

Question 8

Vitamin D Synthesis

Answer 8

1. 7-dehydrocholesterol can be converted to cholecalciferol (Vitamin D3) in the skin by
   UVB
2. Cholecalciferol (Vitamin D3) and Ergocalciferol (Vitamin D2) can both be ingested
   and absorbed through the intestines
3. Vitamin D2 and Vitamin D3 are then converted to calcidiol (25-hydroxy Vitamin D)
   by the liver
4. 1,25-dihydroxy-Vitamin D (calcitriol) is the active form and is synthesized by the
   kidneys

Question 9

Hemidesmosomes are part of what and do what

Answer 9

Important in basal cell layer; attach basal cells are firmly to the basal lamina of the dermal epidermal junction
• Antibodies to proteins in the hemidesmosomes may cause autoimmune blistering diseases such as bullous pemphigoid
• Genetic defects in Collagen VII cause Dystrophic Epidermolysis Bullosa
• Genetic defects in Laminin-5 cause Junctional EB

Question 10

Desmosomes funtion in the basal membrane is to

Answer 10

Attach keratinocytes to each other;

Antibodies to proteins in the desmosomes may cause autoimmune blistering diseases such as pemphigus vulgaris
Congenital defects in Keratin filaments 5 and 14 cause Epidermolysis bullosa simplex
Tonofilaments: protein structures (keratin filaments) that insert into the dense plaques of desmosomes on the cytoplasmic side of the plasma membrane

Question 11

stratum spinosum

Answer 11

• Has a “prickly” or spiny appearance due to desmosome attachments between cells
• intercellular adhesion depends upon the tonofilament-desmosome interaction in the
distribution of stress
• synthesis of involucrin and membrane coating granules begins in this layer

Question 12

stratum granulosum

Answer 12

• the cells of this layer contain different types of granules
• Keratohyalin granules contain Profilaggrin (filaggrin precursor). Filaggrin cross-links
keratin tonofilaments and is important in the barrier function of the skin. Filaggrin is
mutated in dry skin conditions including ichthyosis and atopic dermatitis.

Question 13

stratum lucidum

Answer 13

• under the light microscope, a thin, light staining band seen only in thick skin
• cells of this layer no longer have nuclei or organelles

Question 14

stratum corneum

Answer 14

• the outermost layers of epidermis
• keratinocytes have lost their nuclei and organelles and the entire cell is filled with keratin • desmosomes still connect tightly packed adjacent cells

Question 15

Papillary Layer (of dermis)

Answer 15

• site of attachment to epidermis and necessary to its development and differentiation • contains capillary network that is blood supply for epidermis
• pathway for defense cells
• contains Meissner’s corpuscles which sense touch

Question 16

Reticular Layer

Answer 16

• contains extensive collagen and elastic fibers that provide strength and flexibility
• houses (along with hypodermis) epidermal derivatives such as glands and hairs and plays a major
role in their development and functioning
• pathway for major blood vessels arranged specifically to facilitate thermoregulation • site of nerve tracts and major sensory receptors
• Pacinian corpuscles sense vibration, pressure and touch



Question 17

Meissner’s corpuscles

Answer 17

• detect delicate touch
• are most commonly found in the dermal papillae of thick skin
• consist of Schwann cells and sensory nerve terminals wrapped by fibroblasts and collagen

Question 18

Pacinian corpuscles

Answer 18

-are rapidly adapting receptors that detect changes in deep pressure (vibrations)
-are found in the dermis of both thin and thick skin
-large structures resembling an onion
-the concentric layers are composed of flattened connective tissue-like cells interspersed with
intercellular fluid and collagen
-a single sensory nerve fibers terminates within this structure

Question 19

Apocrine sweat glands

Answer 19

-Specialized sweat glands located in the axillary, pubic and perianal regions
-produce a milky, viscid, carbohydrate-rich secretion that is initially odorless; subsequent bacterial
action leads to a characteristic axillary body odor
-begin to function in puberty
-have ducts which empty into hair follicles just above sebaceous glands

Question 20

Eccrine sweat glands

Answer 20

• Traditional sweat glands distributed over most of the body
• Not found in the lips, under the nails or on the glans penis, glans clitoris, or labia minora
• Watery, enzyme-rich secretion, initially isotonic, becomes hypotonic as Na+ is reabsorbed by the ducts
• Important for thermoregulation

Question 21

Sebaceous glands

Answer 21

• Oil glands which secrete sebum, a complex mixture of lipids
• develop along with hair follicles and empty their secretion into the upper one-third of hair follicles
• development accelerated at puberty

Question 22

Where are Meissner’s and Pacinian corp?

Answer 22

MP’s are important for PR - meins in papillary and pacinian in reticular

Question 23

The “factory” of the dermis that produces collagen fibers, elastic fibers and ground substance is -

Answer 23

fibroblast

Question 24

Which collagen subtype is associated with the basement membrane?

Answer 24

Collagen IV

Question 25

A CD34+ cell is a ….

Answer 25

hematopoetic stem cell

Question 26

Sucquet-Hoyer canal

Answer 26

smooth muscle derived valve-like structure, blood may be directed toward the skin during overheating, or away from the skin in hypothermia

Question 27

intracellular adhesion molecules (ICAMs)

Answer 27

Modulation of inflammation/leukocyte trafficking – via the expression of intracellular adhesion molecules (ICAMs) white blood cells begin the process of first adherence and rolling, and second diapedesis, so that they may exit the vasculature to fight infection in the skin and soft tissue

Question 28

Auspitz sign

Answer 28

Seen in psoriasis, occurs when hardened skin forcefully removed because suprapapillary plate is exposed and capillaries bleed as “pinpoints”

Question 29

Verrucas

Answer 29

benign, virally induced neoplasms (growth) that require an increased blood supply simply to support the virally-proliferating cells. Typified by brownish capillary structures in the center of them

Question 30

CD16 is expressed on

Answer 30

immature neutrophils, a sign of neutropenia

Question 31

leukocytoclastic vasculitis

Answer 31

common disease involving the post-capillary venules, due to the precipitation of immune complexes in the walls of vessels - pressure to skin does not make redness go away because redness due to RBC’s in the tissue space

Question 32

Pruritus (itch)

Answer 32

originates in free nerve endings near the dermoepidermal junction and is conducted centripetally by afferent nerves entering the spinal cord via the dorsal roots. These afferent nerves for pruritus are small, unmyelinated C fibers with a slow conduction rate.

Question 33

What does a Pacinian corp look like under a microscope?

Answer 33

Onion

Question 34

Define the “thirds” of a hair follicle

Answer 34

infundibulum representing the upper third, the isthmus being the middle third (from the sebaceous duct to the insertion of the arrector pili), and the matrical area representing the lower third.

Question 35

finasteride

Answer 35

a 5-α-reductase inhibitor, which block conversion of testosterone to 5-dihydrotestosterone, are used in the treatment of male pattern baldness

Question 36

What triggers sweating?

Answer 36

Sympathetic autonomic system but more specifically - acetylcholine secretion; important when considering drug effects

Question 37

Apocrine glands

Answer 37

located only in the axillary and anogenital area. Although present at birth, they remain small and nonfunctional until after puberty

Question 38

chromohidrosis

Answer 38

Colored sweat, apocrine gland dysfunction

Question 39

Apoeccrine glands

Answer 39

In axilla, respond to choline stimulus, 10x amount of sweat as eccrine glands

Question 40

hyperhidrosis

Answer 40

excessive sweating, involves either eccrine glands or apoaccrine glands - botox can be used to treat