Skin Appendages

Question 1

What are the two types of sweat glands?

Answer 1

• Aprocrine

- Ecrine

Question 2

Where is the ecrine sweat gland most often found?

Answer 2

palms and soles

Question 3

Explain process of sweating.

Answer 3

• cholingergic response regulated by certain neurotransmitters (Acetyl-CoA)
• Sweat evaporated and causes goose bumps due to stimulation and contraction of arrector pili muscle

Question 4

What is the composition of ecrine sweat? (6 things)

Answer 4

Salts
water
urea
ammonium ion
amino acids
small proteins

Question 5

Describe the apocrine gland? Where found? What is the type of sweat?

Answer 5

• Assoc. with hair follicles found in armpits, perineal region, and external ear canal
• milky, white odorless secretion
• produces odor when exposed to cutaneous bacteria
• the scent gland found in animals

Question 6

What is the sebaceous gland?

Answer 6

• appendaged to the hair follicle

- produces an oily substance (sebum)

Question 7

What does sebum contain? What is its function?

Answer 7

• triglycerides
• wax esters
• free fatty acids
• cholesterol

Function unknown but maybe linked to water repellency

Question 8

When does sebum start containing fatty acids?

Answer 8

Not when first secreted, but P.acnes bacteria produces a lipase that hydrolyzes triglyceride to a fatty acid

Question 9

What happens when the liquid and solid phase of sebum are out of balance?

Answer 9

May contribute to pathogenesis of acne which is an infection of the hair follicle

Question 10

What regulates acne?

Answer 10

Oil secretion is exacerbated in acne and regulated by Androgens (like testosterone)

Question 11

What is an effective acne treatment?

Answer 11

Inhibitors of 5-alpha reductase Type I like sprionolactone and finasteride

Question 12

What does 5-alpha reductase Type I do?

Answer 12

• produces a more potent Dihydroxytestosterone (DHT).

- The enzyme catalyzes the reaction from testosterone to DHT

Question 13

What are the characteristics of the nail plate?

Answer 13

Consists of 3 cornified keratin layers:

• Dorsal nail plate (dense, hard, few cell layers)
• Intermediate nail plate (softer keratin, 3/4 of nail plate)
• Ventral nail plate (thin with 1-2 cell layers, soft keratin and connects to substratum)

Question 14

What are the characteristics of the nail bed?

Answer 14

• noncornified soft tissue underneath the nail plate, heavily vascularized
• extends from lunula to hyponychium

Question 15

What are the characteristics of the nail matrix?

Answer 15

• A thick layer of highly proliferative epithelial tissue, responsible for formation of nail plate
• lower cell layers contain melanocytes which likely confer to the pigmentation of the nail plate
• This layer is heavily vascularized

Question 16

What are the characteristics of the nail (as compared to the SC)?

Answer 16

• contain 25 layers of flattened, dead keratinized cells fused into a hard, slightly elastic plate (0.5-1mm thick)
• high in disulfide linkages compared to SC (10.6% vs. 1.2%)
• Holds less water than SC (25% vs 300%)

Question 17

How fast do nails grow?

Answer 17

finger nails 3 mm per month (30-50% slower for toe nails)

Question 18

What are the 5 typical nail diseases?

Answer 18

• Onychomycosis (nail fungus)
• Onycholysis (nail loss)
• Nail psoriasis (pitting and white spots)
• Infected eponychium (hang nail)
• Brittle, dry nails

Question 19

Explain drug delivery to nail.

Answer 19

• Nail has very little lipid layer unlike the SC and acts like a hydrophilic gel structure. So hydrophobic route is unlikely and water solubility is important.
• Drugs must frequently penetrate the nail plate to get to infection.
• Agents that reduce the disulfhydryl bonds open up the nail plate

Question 20

Explain “nail perm” method to effectively deliver drugs through nail plate.

Answer 20

• Agents that reduce the disulfhydryl bonds open up the nail plate
• Combine a nail perm with ammonium thioglycolate or acetyl cysteine with hydrogen bond disruptors like urea