LAYER 2: THE DERMIS:
- Structure of the Dermis:
o Mostly Extracellular Matrix:
▪ Extracellular Collagen
▪ Elastin
o Contains Some Cells:
▪ Fibroblasts: Synthesis and degradation of connective tissue
▪ Histiocytes/Macrophages: Phagocytic cells
▪ Mast cells: Secretory cells 🡪Vasoactive Mediators (histamine) 🡪 Skin Allergies. ▪ Lymphocytes: Small number collect around blood vessels
in normal skin
o Also contains Neurovascular & Other Auxillary Skin Structures:
▪ Blood Vessels
▪ Nerves
▪ Sweat Glands
▪ Hair Follicles (And Arrector Pili – The Smooth Muscle of the Hair Follicle)
o 2 Layers:
▪ (R) - Reticular Layer (thick Collagen, lower layer) - much stronger
▪ (P) - Papillary layer (fine Collagen, upper layer) - weaker
o Connective Tissue of the Dermis:
▪ #1 Collagen = Very tough, fibrous protein – High Tensile Strength
• The Predominant Protein of the Dermis (As opposed to Keratin of the Epidermis) ▪
Elastin = Provides Elasticity to Skin. – Deformity with Memory.
▪ Glycosaminoglycans (GAGs) = Absorb water – Provide Viscosity.
• Hyaluronan backbone with glycoprotein branches.
LAYER 3: THE HYPODERMIS:
- Structure of The Hypodermis:
o Composition:
▪ Mostly Fat (Adipose Cells)-(Thickest in Abdomen)
▪ Blood Vessels
▪ Nerves
o Functions:
▪ Insulates the body
▪ Stores Energy
AUXILLARY COMPONENTS OF SKIN:
- Vasculature:
o Abundant network of dermal vessels
o Functions:
▪ Nutrition of Skin Tissue:
▪ Regulation of Body Temperature:
• Conducts heat from Interior to Exterior 🡪 Heat loss to Environment
• Vasodilation/constriction Important in Thermoregulation
▪ Blood Reservoir:
• Under conditions of circulatory stress (Eg. Exercise/Haemorrhage/Shock),
- Structure of the Dermis:
o Mostly Extracellular Matrix:
▪ Extracellular Collagen
▪ Elastin
o Contains Some Cells:
▪ Fibroblasts: Synthesis and degradation of connective tissue
▪ Histiocytes/Macrophages: Phagocytic cells
▪ Mast cells: Secretory cells 🡪Vasoactive Mediators (histamine) 🡪 Skin Allergies. ▪ Lymphocytes: Small number collect around blood vessels
in normal skin
o Also contains Neurovascular & Other Auxillary Skin Structures:
▪ Blood Vessels
▪ Nerves
▪ Sweat Glands
▪ Hair Follicles (And Arrector Pili – The Smooth Muscle of the Hair Follicle)
o 2 Layers:
▪ (R) - Reticular Layer (thick Collagen, lower layer) - much stronger
▪ (P) - Papillary layer (fine Collagen, upper layer) - weaker
o Connective Tissue of the Dermis:
▪ #1 Collagen = Very tough, fibrous protein – High Tensile Strength
• The Predominant Protein of the Dermis (As opposed to Keratin of the Epidermis) ▪
Elastin = Provides Elasticity to Skin. – Deformity with Memory.
▪ Glycosaminoglycans (GAGs) = Absorb water – Provide Viscosity.
• Hyaluronan backbone with glycoprotein branches.
LAYER 3: THE HYPODERMIS:
- Structure of The Hypodermis:
o Composition:
▪ Mostly Fat (Adipose Cells)-(Thickest in Abdomen)
▪ Blood Vessels
▪ Nerves
o Functions:
▪ Insulates the body
▪ Stores Energy
AUXILLARY COMPONENTS OF SKIN:
- Vasculature:
o Abundant network of dermal vessels
o Functions:
▪ Nutrition of Skin Tissue:
▪ Regulation of Body Temperature:
• Conducts heat from Interior to Exterior 🡪 Heat loss to Environment
• Vasodilation/constriction Important in Thermoregulation
▪ Blood Reservoir:
• Under conditions of circulatory stress (Eg. Exercise/Haemorrhage/Shock),
