Dermis and Adnexal structures

Question 1

What structures are within the dermis?

Answer 1

• blood vessels
• nerves
• adnexal structures (hair, glands, etc.)

Question 2

What are the two layers of the dermis?

Answer 2

1. papillary dermis

2. reticular dermis

Question 3

What is the purpose of the dermis?

Answer 3

Structural & physiologic support network

Provides major tensile strength of skin

Question 4

Which layer is more superficial?

Answer 4

Papillary dermis

Question 5

Which layer has thin collagen fibers? Which has thick?

Answer 5

Thin: papillary

Thick: reticular

Question 6

Which layer has elastic fibers?

Answer 6

Reticular dermis

Question 7

What are the three building blocks of the dermis? And what do they do?

Answer 7

1. Collagen – forms the tensile strength
2. Elastic fibers– allow for resilience
3. Ground substance– facilitates diffusion

Question 8

Which type of collagen is most prevalent in the dermis?

Answer 8

Collagen I: >85% weight of dermis

Question 9

What are the steps of collagen production

Answer 9

1. PROcollagen synthesized within fibroblasts
2. Excreted extracellularly
3. Cleaved enzymatically into TROPOcollagen
4. Tropocollagen aggregates, becomes cross-linked

Question 10

Why is vitamin C necessary for collagen production

Answer 10

Cross-linking (last step) is dependent upon the co-factor vitamin C

Question 11

What causes scurvy?

Answer 11

Vitamin C deficiency resulting in decreased mature collagen

This can lead to hemorrhage because of decreased support of blood vessels

Question 12

What is a congenital disorder of collagen production?

Answer 12

Ehlers-Danlos Syndrome= a family of disorders based on erroneous collagen synthesis

Question 13

What are symptoms of Ehlers-Danlos syndrome?

Answer 13

• Mutations at various stages of collagen production yield findings such as:
– hyperextensible skin 
– hyperextensible joints 
– fragile blood vessels 
– poor wound healing

Question 14

What is solar elastosis?

Answer 14

An acquired disorder from sun damage to elastic fibers

Question 15

What is a congenital disorder of elastic fibers?

Answer 15

Pseudoxanthoma Elasticum

• Caused by a mutation in MDR gene which causes calcified, brittle elastic fibers

“PLUCKED CHICKEN SKIN”

Question 16

What is the ground substance?

Answer 16

The “pie filling”

• gelatinous substance that holds and absorbs 10,000x its weight in water
• held together by fibronectins

Question 17

What are two GAGs (glycosaminoglycans) within the ground substance?

Answer 17

– hyaluronic acid
– dermatan sulphate

These were highlighted in the slides, so they may be important

Question 18

What are the two important types of nerves?

Answer 18

• Type A- heavily myelinated, conduct rapidly
-carries touch, proprioception, muscle stretch receptors, pain

• Type C fibers- unmyelinated, slow-conducting
-convey sensation of diffuse, dull, non-localizing
– temperature and itching sensations

Question 19

What are two disorders of capillary loops?

Answer 19

Psoriasis, verruca

Question 20

What can cause an itch?

Answer 20

– dry skin (xerosis)
– infection (HIV)
– infestation (scabies or lice)
– metabolic disorders (renal failure)

Question 21

What is vasculitis?

Answer 21

Inflammation of the capillaries and venules

“Palpable purpura” - combination of inflammation and hemorrhage

Question 22

What’s the difference between Meissner’s and Pacinian corpuscles? Which one’s pine cone/ onion like?

Answer 22

They are both specialized skin receptors

Meissners: “pine- cone” like, involved in fine touch, highest density on pulps of digits, located in DEJ (dermis, epidermis junction

Pacinian: “onion” like, involved in pressure and vibration, highest density on genitals, located in the dermis,

Question 23

What is the rule of three’s in hair? (hint: growth cycles)

Answer 23

Hairs randomly engaged in 1 of 3 cycles
– anagen (growth) – 85%
– telogen (rest) – 10-15%
– catagen (involution) – 1-5%

• Cycles follow a “basic rule of threes”
– anagen – 3 years
– telogen – 3 months
– catagen – 3 weeks (or less)

Question 24

What is androgenic hair loss?

Answer 24

“male-pattern” baldness

Caused by conversion of testosterone to DHT

Question 25

T/F: Finasteride is the preferred treatment for men and women?

Answer 25

Both

Great in men, dangerous for women in reproductive age and we’re not sure about older ladies

inhibitor of 5-a-reductase which blocks conversion of testosterone to DHT

Question 26

Which gland produces watery, odorless sweat?

Answer 26

Eccrine Glands

VITAL to thermoregulation
Numerous upon forehead, cutaneous lip, palms/soles
Merocrine secretion

Question 27

What sweat glands deal with acne

Answer 27

Sebaceous glands- they lubricate terminal (thick) hairs

acne: disease of pilosebaceous unit

Question 28

How do holocrine glands work?

Answer 28

Whole cells are shed and disintegrate, releasing contents.

Question 29

What is miliaria?

Answer 29

Blocked sweat ducts (eccrine glands)

“prickly heat” in babies, febrile, etc.

Question 30

You have a mutation in the EDA gene, affecting your eccrine developing which affects your temperature regulation… what is your condition? What other problems could you see?

Answer 30

Anhidrotic Ectodermal Dysplasia

Other ectodermal problems
– sparse hair, abnormal teeth, etc.

Question 31

What sweat glands do you have in your armpit?

Answer 31

Apocrine glands

• These work by a hybrid method of “decapitation” secretion.
• They are in your armpit probably because they can secrete 10x more sweat than eccrine glands

Question 32

How can you treat super sweaty hands?

Answer 32

Botulinum toxin injections

• blocks secretion by preventing acetylcholine release
• expensive & painful