Dermis and subcutaneous tissue Flashcards
Layers of dermis:
Papillary: loose connective tissue beneath the epidermis.
Reticular: Dense dermal collagen.
Functions of the dermis:
- Structure and flexibility.
- Vascular support.
- Immunologic protection.
- Nerve sensation.
Function of ECM:
Supports cells of the dermis.
Components of ECM:
- Collagen
- Elastic fibers
- Extrafibrillar matrix
Collagen produced by:
Dermal fibroblasts.
Types of collagen:
Collagen I: most abundant.
Collagen III: Increased levels during embryogenesis, infancy, wound healing.
Collagen IV, VII, XVII are in the basement membrane.
Structure of elastic fibers:
- Microfibrils (mainly fibrillin)
2. Elastin
Extrafibrillar matrix composition:
- Water
- Electrolytes
- Plasma proteins
- Proteoglycans
Proteoglycan structure and function:
Structure: Protein core + glycosaminoglycan.
Function: bind large amounts of water.
Fibroblasts:
Derived from mesoderm.
Synthesize ECM components:
Collagen
Elastic fibers
Ground substance
High metabolic activity.
Meissner:
Pacinian:
Fine touch.
Deep pressure, vibration.
Marfan syndrome:
Autosomal dominant.
Production of weak elastic tissue due to a defect in synthesizing fibrillin.
Variable expression:
Most often CV abnormalities dominate.
Dislocation of lens (suspensory ligament is elastic).
Pectus excavatum.
Striae.
Ehlers-Danlos syndrome:
Abnormalities of collagen structure, production, processing, or assembly.
Hypermobile joints and really stretchy skin.
Morphea:
Autoimmune disease, causes sclerosis.
Violaceous plaques, sclerotic plaques. Limb and joint complications. Neurologic involvement. En coup de sabre.
Women > men.
Systemic sclerosis:
Autoimmune disease.
Multisystem disease characterized by vascular dysfunction, excessive production of collagen that primarily targets the skin and visceral organs, and immune dysfunction.
Middle-aged women, increased incidence in the black female population.
Clinical features: Sclerosis of the skin (microstomia, sclerodactyly) Raynaud's phenomenon Telangiectasia Arthritis Internal organ involvement