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D&D Unit 4 > Dermis and Adnexal Structures (complete) > Flashcards

Dermis and Adnexal Structures (complete) Flashcards

1
Q

What is the dermis?

A
  • Structural and physiologic support network
  • Provides major tensile strength of skin
  • Thickness varies w/ location

Contains:

  • Blood vessels
  • Nerves
  • Hair, glands
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2
Q

Describe the structure of the dermis

A
  • Lies between epidermis and subq

Contains adnexal structures:

  • Hair
  • Sweat glands
  • Sebaceous glands
  • Vessels
  • Nerves
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3
Q

What are the zones of the dermis?

A
  • Papillary dermis

- Reticular dermis

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4
Q

Describe the papillary dermis

A

Upper layer of dermis

  • Thin collagen bundles
  • Interlocks w/ epidermal rete (increases strength and SA)
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5
Q

Describe the reticular dermis

A

Deeper layer of dermis

  • Thick collagen bundles
  • Visible elastic fibers
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6
Q

What are the three building blocks of the dermis?

A

Collagen: tensile strength

Elastic fibers: allow for resilience

Ground substance: facilitates diffusion

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7
Q

What is the most common/important collagen found in humans?

A

Collagen I (85% of adult dermis)

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8
Q

Describe the production of collagen

A
  • Procollagen synthesized w/ fibroblasts
  • Excreted extracellularly
  • Cleaved enzymatically into tropocollagen
  • Tropocollagen aggregates => becomes crosslinked
  • Cross-links in presence of Vit C (co-factor)
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9
Q

What is scurvy?

A
  • Deficiency of Vit C
  • Deficiency => decreased mature collagen
  • Signs/symptoms develop after 1-3 months of deprivation

An ACQUIRED disease

Key findings:

  • keratoitic plugging of hairs
  • perifollicular hemorrhage
  • corkscrew hairs
  • hemorrhagic gingivitis
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10
Q

What does hemorrhage occur w/ scurvy?

A
  • Lack of collagen support for blood vessels
  • Leads to rupture & hemorrhage

Bleeding gums!!! arrrr scurvyyy

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11
Q

What is Ehlers-Danlos Syndrome?

A

A CONGENITAL disease of collagen production

  • family of disorders based on erroneous collagen synthesis

Mutations of collagen production cause:

  • Hyperextensible skin
  • Hyperextensible joints
  • fragile blood vessels
  • Poor wound healing

REMEMBER: It’s collagen disorder, not an elastic disorder!!!!

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12
Q

What are elastic fibers?

A
  • Minor constituent of dermis => provides resiliency
  • Thin fibers (1-3 microm)
  • Intertwins among collagen bundles
  • Special stains are required to visualize!!!
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13
Q

What is solar elastosis?

A
  • Sun-damaged elastic fibers
  • Happens over time — especially in Colorado

An ACQUIRED disease

Histology shows:
- basophilic (blue) material w/in superficial dermis

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14
Q

What is pseudoxanthoma elasticum?

A

A CONGENITAL disease of elastic tissue

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

Associated w/:

  • Plucked chicken skin
  • Systemic hypertension
  • Angioid streaks in retina
  • Arterial rupture
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15
Q

What is the ground substance?

A
  • Pie filling of dermis
  • Glued together w/ fibronectins
  • Functions as a sponge

Contains:

  • hyaluronic acid
  • dermatan sulphate
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16
Q

Discuss the blood vessels of the dermis

A
  • Provides nutritional support/diffusion to the epidermis
  • Skin vessels considered as 2 plexi: superficial and deep!!

Remember: epidermis has NO VASCULATURE!

17
Q

Describe generally disorders of capillary loops

A
  • Dilated, tortuous capillaries are noted in these diseases
  • these diseases have increased epidermal turnover

Ex:

  • Psoriasis
  • Verruca
18
Q

Describe palpable purpura

A
  • Combo of inflammation and hemorrhage

When you press on this, there is no blanching (w/ a sunburn there is — turns white when pressure is applied)

19
Q

What are two important types of nerve fibers found in the skin?

A

Type A: heavily myelinated — conduct rapidly

Type C: unmyelinated — slow conducting

20
Q

What is the clinical term for itch? What triggers itch?

A

Pruritus!!!

Triggers:

  • dry skin
  • infection (e.g. HIV)
  • infestation (scabies, lice)
  • metabolic disorders (renal failure)

Otherwise oftentimes you don’t know what causes itch!!!

21
Q

What are two types of specialized skin receptors?

A
  • Meissner’s Corpuscles

- Pacinian Corpuscles

22
Q

Describe Meissner’s Corpuscles

A
  • Found in fine touch!
  • High density on pulps of digits
  • Looks like a pine cone
23
Q

Describe Pacinian Corpuscles

A
  • Involved in pressure and vibration
  • Highest density on genitals
  • Look like an onion!
24
Q

What are the different types of hair?

A

Types:

  • Terminal (dark, thick, coarse)
  • Vellus (peach fuzz, fine, thin)
25
Q

Describe the anatomy of a hair follicle

A

Divided into thirds

1) Infundibulum
2) Isthmus
3) Matrical region

26
Q

Describe androgenic hair loss

A
  • AKA pattern baldness
  • Characteristic loss
  • Affects 50% of pop’n
  • Converts testosterone to DHT => miniature follicle
27
Q

What are some treatments for hair loss? How does it work?

A

Finasteride

  • Selective inhibitor of 5-alpha-reductase
  • Blocks conversion of testosterone to DHT
28
Q

What are sebaceous glands?

A
  • Lubricate thick terminal hairs

- Cause acne

29
Q

Describe the pathogenesis of acne

A
  • Disease of pilosebaceous unit
  • Abnormal follicular maturation => white/black heads
  • Causes overgrowth of bacteria => dermal inflammation
30
Q

What are eccrine glands?

A
  • Odorless, watery sweat secreted by these glands
  • Vital for thermoreg
  • On cutaneous lip, palms, soles
  • Sympathetic innervation but utilizes Ach

Merocrine secretion

31
Q

What are some acquired disorders of sweating?

A
  • Heat shock

- Antiperspirants

32
Q

What is miliaria?

A
  • Blocked sweat ducts => Ruptured eccrine glands

- Manifestations depends on blockage site

33
Q

What are apocrine glands?

A
  • Outgrowths of upper bulge PEG
  • Located in axillary and anogenital area
  • Small/nonfunctional until puberty
  • Produce stickier/gluier fluid than eccrine — SIALOMUCIN
  • Odorless until contact w/ normal skin flora
34
Q

What are apoeccrine glands?

A
  • Hybrid sweat glands
  • Located in axila
  • Likely play role in axillary hyperhidrosis

Secrete 10x as much sweat as eccrine glands!!

35
Q

How can you treat hyperhidrosis?

A
  • Secretion is dependent upon Ach release
  • SOOOO let’s block its release!!

Botulinum toxin blocks Ach release (aka botox) — expensive and painful!

D&D Unit 4 (18 decks)

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