Adnexal Structures

Question 1

3 types of pilosebaceous units?

Answer 1

lanugo (fetal), vellus (fine), terminal (coarse, often darker)

Question 2

pilosebaceous unit consists of?

Answer 2

a hair follicle and its associated sebaceous gland

Question 3

The hair follicle consists of?

Answer 3

3 longitudinal segments: the hair bulb (inferior segment), the isthmus (middle segment) which extends from the point of insertion of the arrector pili muscle to the sebaceous gland), and the infundibulum (upper segment) refers to the portion from the skin surface to the sebaceous gland.

Question 4

Sebaceous glands found where?

Answer 4

in greatest density on the face and scalp, but are found everywhere except palms and soles. The chest and back also have a high density of sebaceous glands. With the exception of a few distinct locations (vermilion lips, orogenital mucosae, areolae, and eyelids), sebaceous glands are always associated with hair follicles.

Question 5

Sebaceous glands produce what?

Answer 5

sebum. composed of triglycerides, free fatty acids, squalene, wax and sterol esters, and free sterols. Secretion is holocrine (sebocytes disintegrate and release their sebum as they migrate toward the duct.) Flow of sebum is continuous, but variable among individuals.

Question 6

factors affecting sebum production?

Answer 6

Androgen production at puberty, especially 5α-dihydrotestosterone (DHT), stimulates the sebaceous gland and increases sebum production. major contributor to the development of acne. Sebum production remains constant after puberty until menopause in women or until the 6th or 7th decade in men

Question 7

microorganisms that can be present in hair?

Answer 7

Malassezia spp., Staphylococcus epidermidis, and Propionibacterium spp., Demodex folliculorum, the hair follicle mite. inhabit the hair follicles in sebaceous-rich sites.

Question 8

hair follicle cycle?

Answer 8

3 stages. majority in the growth phase with the rest in the resting phase. length of the growth phase varies by site, longest duration on the scalp where hair grows the longest. Hairs shed after they have transitioned to the resting phase at which point the cycle begins again. 100-200 hairs shed each day. Each follicle cycles independently, fairly uniform density of hair

Question 9

3 phases of hair cycle?

Answer 9

anagen (growth, 2-6 yrs), catagen (regression, 2-3 weeks), telogen (resting, 3 mo)

Question 10

what is telogen effluvium?

Answer 10

occurs when a greater proportion of hair follicles enter telogen phase simultaneously as the result of a stressor (pregnancy, fever, surgery, illness, malnutrition)

Question 11

clinical manifestation of telogen effluvium?

Answer 11

increase in hairs being shed approximately 3 months (duration of the telogen phase) after the event. Hair loss slowly abates, and hairs return to a more normal distribution of phases.

Question 12

telogen effluvium in neonates?

Answer 12

In neonates, a greater proportion of hair follicles are present in telogen phase resulting in shedding or hair loss a few months after birth. This has been referred to as telogen effluvium of the newborn

Question 13

what is alopecia areata?

Answer 13

autoimmune condition characterized by the sudden development of round, smooth patches of hair loss (alopecia)

Question 14

possible outcomes of alopecial areata?

Answer 14

Progression to large areas of hair loss can occur to the point of complete hair loss on the scalp (alopecia totalis) or the entire body (alopecia universalis). Spontaneous regrowth of hair can also be seen. nail changes including pitting.

Question 15

how can you differentiate alopecia areata from tinea capitis?

Answer 15

lack of erythema, scaling, or pustules

Question 16

treatment for alopecia areata?

Answer 16

Treatment includes topical corticosteroids and intralesional corticosteroids most commonly. Chronic use of systemic immunosuppressants not commonly employed d/t associated risks.

Question 17

what is Anagen effluvium? course?

Answer 17

hair loss that is the result of medications, such as chemotherapy. This typically develops 2-3 weeks after drug administration. Hair regrows after the medication is stopped.

Question 18

what are the major sweat glands in humans?

Answer 18

eccrine and apocrine glands. They vary in type and density, depending on anatomic location.

Question 19

eccrine sweat glands activity/innervation?

Answer 19

active from birth. Innervation is provided by postganglionic sympathetic fibers which are controlled by the hypothalamic sweat center. In contrast to other sympathetic fibers, acetylcholine (not norepinephrine) is the principal neurotransmitter.

Question 20

the eccrine secretory unit is composed of?

Answer 20

coiled secretory portion in the lower dermis and subcutaneous tissue. This drains into a long thin duct with an apical portion (acrosyringium) that opens directly onto the skin surface.

Question 21

2 cell types within single cell layer in secretory coils?

Answer 21

1) large clear cells responsible for the gland’s secretion of electrolytes and water
2) dark cells, of unknown function, thought to produce sialomucin.
Myoepithelial cells surrounding these cells are thought to enhance delivery of sweat to the skin surface

Question 22

Continuous secretion of sweat provides what 3 major functions for the body?

Answer 22

1) thermoregulation via evaporative heat loss
2) maintenance of electrolyte balance
3) maintenance of a moist stratum corneum to facilitate tactile skills and pliability of the palms and soles.

Question 23

where are apocrine sweat glands found?

Answer 23

localized to specific anatomic sites (axillae, anogenital region, periumbilical region, areolae, nipples, vermilion border of the lip)

Question 24

Modified apocrine glands are found where?

Answer 24

external auditory canals (ceruminous glands) and eyelid margins (glands of Moll). These glands secrete oily, viscous, odorless fluid that is rich in precursors of odoriferous substances. bacteria degradation (on skin) results in BO

Question 25

what causes increased secretion?

Answer 25

response to local or systemic catecholamines and cholinergic agonists, but mechanisms involved in physiologic secretion are poorly understood. Enlargement of the glands occurs with puberty likely due to androgenic stimulation.

Question 26

apocrine gland anatomy?

Answer 26

larger than eccrine glands. consist of a secretory portion and a duct that opens into the upper portion of the hair follicle. secretory unit is composed of a single layer of columnar epithelial cells surrounded by myoepithelial cells. duct is composed of a double layer of cuboidal cells, as well as myoepithelial cells

Question 27

acne vulgaris develops why, initially?

Answer 27

result of an increase in sebum production (under hormonal influences) in combination with increased production and impaired shedding of the corneocytes lining the upper portion of the hair follicle leading to plugging of the hair follicles (comedo formation). plugged follicles may rupture, inflammatory response to extruded keratin and sebum

Question 28

what bacteria plays a role in acne pathogenesis?

Answer 28

Propionibacterium acnes, a Gram- positive non-motile rod, found deep within the follicle, also plays an important role. P. acnes releases enzymes that promote follicular rupture and stimulates release of proinflammatory mediators leading to neutrophil recruitment and Th1 responses.

Question 29

what is the non-inflammatory acne?

Answer 29

Comedones are characteristic lesions in non-inflammatory acne, and may be closed (whiteheads) or open (blackheads). Comedones are typically small skin-colored papules (closed), which may have a dilated follicular opening (open).

Question 30

what is inflammatory acne?

Answer 30

Inflammatory acne presents with comedones, but type of inflammatory lesions vary dependent on the type of inflammatory response: pustules develope as the result of a neutrophil predominant response; inflammatory papules, nodules and cysts develope from a mixed inflammatory response (lymphocytes, giant cells, and neutrophils)

Question 31

treatment of acne?

Answer 31

topical retinoids. topical anti-inflammatory agents. systemic agents like abx, contraceptives, isotretinoin

Question 32

what do topical retinoids target? how?

Answer 32

target comedone. mech: normalization of follicular keratinization, expulsion of existing keratinaceous follicular plugs and prevention of formation of new lesions

Question 33

what are topical anti-inflammatory agents? work how?

Answer 33

benzoyl peroxide (BPO) and topical antibiotics (clindamycin, erythromycin). These agents have both anti-bacterial activity against P. acnes as well as anti-inflammatory properties. often used together

Question 34

what are systemic agents used to treat acne?

Answer 34

oral antibiotics, oral contraceptives, and isotretinoin. Oral antibiotics most commonly include doxycycline and minocycline,

Question 35

pathogenesis of rosacea?

Answer 35

multifactorial, but is related to vascular hyperreactivity. Patient present with a history of easy blushing, and over time develop a reddened complexion.

Question 36

additional rosacea features? how different from acne vulgaris?

Answer 36

papules and pustules, telangiectasia, and phymatous change in which overgrowth of sebaceous glands can be seen resulting in the skin appearing swollen or bumpy. The lack of comedones helps to differentiate this from acne vulgaris.

Question 37

rosacea treatment?

Answer 37

overlaps with that for acne, but topical metronidazole and sodium sulfacetamide are more commonly used. more easily irritated, and their tolerance of topical therapy (like retinoids, BP) may be limited. Systemic agents include antibiotics such as doxycycline, minocycline, and erythromycin.