7.1: Intro To Dermatology pt1 Flashcards
4 layers of the skin
Epidermis
Basement membrane (dermal-epidermal junction)
Dermis
Subcutaneous fat
What is the epidermis composed of
Keratinocytes
Where in the epidermis do cells divide in
Basal layer
Cell types of the epidermis
Stratum spinosum
Stratum granulosum
Stratum lucidum (palms and soles only)
Stratum corneum
Progressive differentiation / flattening towards surface
Why is the skin thicker on palms and soles
Composed of stratum lucidum, no nuclei or organelles, tougher skin
Characteristics of stratum corneum
No nuclei or organelles
Cellular progression of epidermis
From basal layer to the surface
Takes 30days
Accelerated in skin diseases e.g psoriasis
Structure of the epidermis
Gap junctions
Adherens junctions
Desmosomes
Tight junctions
Characteristics of gap junctions
Essential for cell synchronization, cell differentiation, cell growth and metabolic coordination
Role of tight junctions
Barrier integrity and cell polarity
Characteristics of desmosomes
Major adhesion complex in epidermis
Anchor keratin intermediate filaments to cell membrane and bridge adjacent keratinocytes
Allow cells to withstand trauma
3 other cells in epidermis
Melanocytes
Langerhans cells
Merkel cells
Characteristics of melanocytes
Dendritic
Distribute melanin pigment to keratinocytes
Number of melanocytes is equal along all skin types
Characteristics of langerhans cells
Dendritic
Antigen-presenting cells
Characteristics of merkel cells
Mechanosensory receptors
3 layers of the dermis
Supporting (Extracellular) matrix - resilience
Papillary dermis
Reticular dermis
Components in the skin dermis
Proteins - collagen (1 and 3), elastic fibres (fibrillin and elastin)
Glycoproteins - fibronectin, fibulin, integrins
Ground substance - glycosaminogylcan, proteoglycan
Function of glycoproteins found in skin dermis
Facilitate cell adhesion and cell motility
What % of the skin dermis is made up of collagen
80-85%
Primary cells in the dermis
Fibroblasts
5 cells within the dermis
Histiocytes
Mast cells
Neutrophils
Lymphocytes
Dermal dendritic cells
Vascular supply of the skin
Deep and superficial vascular plexus, doesn’t cross epidermis
Reason behind Innervation of the skin
Sensory
Autonomic
Cholinergic
Adrenergic
4 nerve cells supplying the skin
Meissner’s corpuscle
Ruffini corpuscle
Pacinian corpuscle
Merkel cell (unencapsulated)
Characteristics of meissner’s corpuscle
Most concentrated in thick hairless skin
Light touch
Characteristics of the Ruffini Corpuscle
Highest density around fingernails
Sensitive to skin stretch
Monitors slippage of objects