Dermis and Adnexal structures Flashcards
What structures are within the dermis?
- blood vessels
- nerves
- adnexal structures (hair, glands, etc.)
What are the two layers of the dermis?
- papillary dermis
2. reticular dermis
What is the purpose of the dermis?
Structural & physiologic support network
Provides major tensile strength of skin
Which layer is more superficial?
Papillary dermis
Which layer has thin collagen fibers? Which has thick?
Thin: papillary
Thick: reticular
Which layer has elastic fibers?
Reticular dermis
What are the three building blocks of the dermis? And what do they do?
- Collagen – forms the tensile strength
- Elastic fibers– allow for resilience
- Ground substance– facilitates diffusion
Which type of collagen is most prevalent in the dermis?
Collagen I: >85% weight of dermis
What are the steps of collagen production
- PROcollagen synthesized within fibroblasts
- Excreted extracellularly
- Cleaved enzymatically into TROPOcollagen
- Tropocollagen aggregates, becomes cross-linked
Why is vitamin C necessary for collagen production
Cross-linking (last step) is dependent upon the co-factor vitamin C
What causes scurvy?
Vitamin C deficiency resulting in decreased mature collagen
This can lead to hemorrhage because of decreased support of blood vessels
What is a congenital disorder of collagen production?
Ehlers-Danlos Syndrome= a family of disorders based on erroneous collagen synthesis
What are symptoms of Ehlers-Danlos syndrome?
• Mutations at various stages of collagen production yield findings such as: – hyperextensible skin – hyperextensible joints – fragile blood vessels – poor wound healing
What is solar elastosis?
An acquired disorder from sun damage to elastic fibers
What is a congenital disorder of elastic fibers?
Pseudoxanthoma Elasticum
• Caused by a mutation in MDR gene which causes calcified, brittle elastic fibers
“PLUCKED CHICKEN SKIN”
What is the ground substance?
The “pie filling”
- gelatinous substance that holds and absorbs 10,000x its weight in water
- held together by fibronectins
What are two GAGs (glycosaminoglycans) within the ground substance?
– hyaluronic acid
– dermatan sulphate
These were highlighted in the slides, so they may be important
What are the two important types of nerves?
• 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
What are two disorders of capillary loops?
Psoriasis, verruca
What can cause an itch?
– dry skin (xerosis)
– infection (HIV)
– infestation (scabies or lice)
– metabolic disorders (renal failure)
What is vasculitis?
Inflammation of the capillaries and venules
“Palpable purpura” - combination of inflammation and hemorrhage
What’s the difference between Meissner’s and Pacinian corpuscles? Which one’s pine cone/ onion like?
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,
What is the rule of three’s in hair? (hint: growth cycles)
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)
What is androgenic hair loss?
“male-pattern” baldness
Caused by conversion of testosterone to DHT
T/F: Finasteride is the preferred treatment for men and women?
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
Which gland produces watery, odorless sweat?
Eccrine Glands
VITAL to thermoregulation
Numerous upon forehead, cutaneous lip, palms/soles
Merocrine secretion
What sweat glands deal with acne
Sebaceous glands- they lubricate terminal (thick) hairs
acne: disease of pilosebaceous unit
How do holocrine glands work?
Whole cells are shed and disintegrate, releasing contents.
What is miliaria?
Blocked sweat ducts (eccrine glands)
“prickly heat” in babies, febrile, etc.
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?
Anhidrotic Ectodermal Dysplasia
Other ectodermal problems
– sparse hair, abnormal teeth, etc.
What sweat glands do you have in your armpit?
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
How can you treat super sweaty hands?
Botulinum toxin injections
- blocks secretion by preventing acetylcholine release
- expensive & painful
