Normal Skin Structure & Function I and II (cont.)

Question 1

What is koilonychia and what is it associated with?

Answer 1

• spooning of the nails

- it is associated with iron deficiency

Question 2

Splitting of the nail from the nail bed is characteristic of what kinds of disease?

Answer 2

some kinds of thyroid disease

Question 3

What characteristic nails develop in Marfan’s syndrome (in which there is a genetic defect in the glycoprotein fibrillin, required fro assembly of elastin filaments)?

Answer 3

long narrow nails

Question 4

What diseases are associated with clubbing of the nails?

Answer 4

• liver disease
• bronchogenic carcinomas
• ulcerative colitis
• particularly associated with cardio-pulmonary diseases

Question 5

What are Beau’s Lines?

Answer 5

transverse grooves at the same level across all nails reflecting past illness at the time the lines were created

Question 6

What characteristic nails occur commonly in patients with psoriasis?

Answer 6

nail pitting

Question 7

What is periungual telangiectasia? What kind of disease is suggested by it?

Answer 7

• dilated capillaries at proximal nail fold

- suggests CT disease such as dermatomyositis (an inflammatory myopathy with skin manifestations) and SLE

Question 8

What is oncomycosis?

Answer 8

dermatophyte fungi infecting the nails

Question 9

Where does onchomycosis occur? What does it suggest?

Answer 9

• very common especially in the elderly
• occurs more often in toenails than fingernails
• the infection can be disfiguring but is otherwise asymptomatic

Question 10

Hair follicles arise from what (histologically)?

Answer 10

invaginations of epidermis into the dermis

Question 11

The shaft of the hair follicle is made up of what five layers?

Answer 11

• connective tissue sheath (outermost layer)
• glassy membrane
• external root sheath
• internal root sheath
• hair shaft

Question 12

Connective tissue sheath

Answer 12

• provides growing root with capillaries and nerves

- continuous with the reticular layer of the dermis

Question 13

Glassy membrane

Answer 13

• basal lamina of hair follice
• very thick
• separates external root sheath from the dermis along the length of the hair shaft

Question 14

External root sheath

Answer 14

• continuous with the epidermis and has same structure

- at base of follicle, external root sheath merges with internal root sheath in a cellular mass called the matrix

Question 15

Internal root sheath

Answer 15

• composed of several layers of cells
• layer nearest hair shaft forms keratinized scales that jut out and interdigitate slightly with the hair cuticle, this helps hold the hair int he shaft
• inner root sheath ends at the level of entry of the sebaceous gland, leaving a space into which sebum is secreted

Question 16

Hair is produced by what cells, where are they located?

Hair shaft?

Answer 16

hair is produced by epithelial cells above the dermal papilla, from which they are separated by a basal lamina

• melanocytes among these give pigment to hair

Question 17

What three layers make up hair?

Answer 17

• central medulla (soft keratin; medulla often absent)
• cortex (hard keratin), which makes up the bulk of the hair
• an outer cuticle formed be a layer of partially overlapping, shingle-like cells

Question 18

Stem cells are present for regenerating the hair follicle as it is periodically shed and re-grown during the normal hair life cycle. There are also stem cells for regeneration of the epidermis after wounding.
Where are these stem cells located?

Answer 18

hair bulge region: a population of cells in the outer root sheath at the insertion point of the arrector pili muscle

Question 19

What is anagen?

Answer 19

cyclic period of growth

Question 20

What is catagen?

Answer 20

cyclic period of regression

Question 21

What is telogen?

Answer 21

cyclic period of rest

Question 22

In normal hair at any given time, approximately what percentage of follicles are in the anagen phase?

Answer 22

80%

Question 23

The length limit for hair on different parts of the body is regulated by the length of the growth phase before hair involutes and is shed.
What is the typical growth phase of scalp follicles?

Answer 23

3-4 years (this is long)

Question 24

What is Telogen Effluviium?

Answer 24

• occurs when too many follicles shift into telogen

- this is the cause of postpartum hair loss and can also be triggered by illness

Question 25

What is Anagen Effluvium?

Answer 25

hair loss due to chemotherapy damage to proilferating follicular epithelium

Question 26

What is Androgenetic Alopecia?

Answer 26

male and female pattern hair loss - is triggered by androgens in the genetically susceptible

Question 27

What is Alopecia areata?

Answer 27

• known to be an autoimmune disease that appears to target several antigens and causes loss of hair follicles in patches (usually) or more extensively
• it can show a remitting relapsing pattern and hair can regrow in denuded areas, although hair loss may be permanent
• it can occur at any age and has a familial component

Question 28

What are four sense organs?

Answer 28

• free nerve endings
• Pacinian corpuscles
• Meissner’s corpuscles
• Merkel cells

Question 29

Free nerve endings

Answer 29

• enter epidermis from dermis
• most respond to temperature and pain
• free nerve endings associated with Merkel cells are thought to function as mechanoreceptors

Question 30

Pacinian corpuscles

Answer 30

• look somewhat like an onion in section
• located deep in dermis
• respond mainly to pressure stimuli

Question 31

Meissner’s corpuscles

Answer 31

• usually located in the dermal papillae
• most numerous in fingertips, soles of feet, lips, and genitalic area
• oval in shape, composed of coiled nerve endings surrounded by modified Schwann cells