Dermis and Subcutaneous Tissue

Question 1

What is the dermis derived from and what are its functions?

Answer 1

Derived from mesoderm

• functions:
  
  • structure and flexibility
  • vascular support
  • immunologic protection
  • nerve sensation
• contains adnexal structures

Question 2

What is the main part of the dermis?

Answer 2

ECM

Question 3

What is the funciton of the ECM and what are its components?

Answer 3

• supports cells of the dermis and regulates cell functions
• components:
  
  • collagen
  • elastic fibers
  • extrafibrillar matrix

Question 4

How much of the dermis is collagen? what produces it? What are some properties of collagen?

Answer 4

• main component of dermis: 20% of skin volume, 75% of dry skin weight
• produced by dermal fibroblasts
• properties: very strong, stretches very little

Question 5

How many types of collagen are in the skin and what are some roles of the main types?

Answer 5

there are 12-28 collagen types in the skin

• collagen I: most abundant (80-90%)
• Collagen III: 2nd most,
  
  • increased levels during embryogenesis/infancy, wound healing
• Collagen IV, VII, XVII are basment membrane

Question 6

What is the structure of elastic fibers and what is their role?

Answer 6

Give skin elasticity

structure= microfibrils (mainly fibrilin) and elastin

Question 7

What is the composition of Extrafibrillar matrix and what is another name for it?

Answer 7

also called ground substance

• water
• electrolytes
• plasma protiens
• proteoglycans

Question 8

what is the structure and functiong of proteoglycans?

Answer 8

• structure
  
  • protein core
  • glycosaminoglycans
    
    • long chain polysaccharides eg dermatan sulfate
• Fucntion: bind large amounts of water (draw water in)

Question 9

Where are fibroblasts derived from and what do they do?

Answer 9

derived from mesoderm

synthesixe ECM components: collagen, elastic fibers, ground substance

Question 10

Describe the process of collagen snthesis

Answer 10

1. translation of the collagen polypeptide on the rough endoplasmic reticulum
2. post-translation modification in the endoplasmic reticulum and golgi complex
   
   • Cleavage of signal peptides
   • Hydroxylation (addition of OH)
   • Glycosylation (addition of glyosyl)
3. Association of a-chains and folding proteins into procollagen triple healix
4. protease cleavage of N and C terminals
5. Assembly and cross-linking with other collagens to form collagen suprastructure

Question 11

What is the role of the pacinian corpuscle? How about the Meissners?

Answer 11

Pacinian: present in weight bearing surfaces, as well as the lips, nipples, penis and clitoris. They are located in the deep dermis and sucutaneous tissue and detect pressure. Deep Pressure

Meissner’s Corpuscles: located just below the epideris in the dermal papillae. are sensitive to light touch and are concentrated on palms and soles

Question 12

What is Marfan syndrome? How do you get it and what is the pathogenesis?

Answer 12

autosomal dominant

mutation in fibrilin

features (variable expression):

tall thin body, long limbs/fingers, scoliosis, flexible joints, striae, myopia, ectopia lentis, aortic dilation/aneruysm, mitral valve prolapse

Question 13

What is Ehlers-Danlos Syndrome?

Answer 13

• group of inherited connective tissue disorders
• abnormalities of collagen structure (type V), production, processing or assembly
• variable inheritance and clinical features based on maturation

Question 14

What causes Morphea and what is it? Who gets it and what does it look like?

Answer 14

autoimmune disease

causes sclerosis (thickening of collagen)

women>men, children=adults

limb and joing complications, neurologic involvement too.

(can cause limbs to be “locked” from intense scarring)

Question 15

What is the pathogeneis of systemic sclerosis and who gets it?

Answer 15

autoimmune disease

middle aged women

widespread sclerosis

Question 16

What are the clilnical features of systemic sclerosis?

Answer 16

• Sclerosis of skin: microstomia, sclerodactyly
• Raynaud’s phenomena
• Telangiectasia (flat red dots on skin from dilated vessels)
• Arthritis
• Internal Organ Invovement: pulomnary fibrosis, renal crises, esophageal dysmotility

Question 17

Describe the general process of wound healing

Answer 17

Injury

hemostasis

inflammation

prolifertion

maturation

Question 18

What is hemostasis?

Answer 18

reflexive vasoconstriction

coagulation through platelet activation

formation of fibrin plug

Question 19

What is inflammation?

Answer 19

hours to 3 days

vasodilation

increased vascular permeability

leukocyte recruitment

Question 20

What is proliferation?

Answer 20

4-12 days

angiogenesis by endothelial cells

collagen, elastin, and matrix synthesis by fibroblasts

re-epithelialization through keratinocytes migration from edges

Question 21

What is maturation?

Answer 21

12 days to 2 years

inflammatory cells cleared

fibroblast apoptosis

blood vessel maturation

collagen maturation

Question 22

WHat is the function of subcutaneous fat and what is it derived from?

Answer 22

derived from mesoderm

functions: energy storage, insulation, shock absortion

Question 23

What is Erythema Nodosum? Who gets it?

Answer 23

• Reactive panniculitis
  
  • streptococcal pharyngitis
  • oral contraceptives
  • inflammatory bowel disease
  • malignancy
• Young women
• tender red nodules on the shins

Question 24

What collagen is the most abundant in adults?

Answer 24

collagen I

Question 25

A 26 yo woman has red nodules on her shin after a strep infection. what does she mostly have and where is the disease?

Answer 25

Erythema Nodulosum: Subcutis