DERMATOLOGIC DISORDERS
I. REVIEW OF THE INTEGUMENTARY SYSTEM
SKIN – also known as the integument which means covering - largest organ system - barrier between external and internal environment
FUNCTIONS OF THE SKIN
1) Protection - protects from trauma (Mechanical, Radiation, Thermal) - thickened skin on palms and soles provides additional covering against trauma r/t constant use - Intact skin - primary defense (prevents invasion of microorganisms) - secretions(from sebaceous gland) are oily and slightly acidic (prevents/limits the mult. of mcgs)
2) Maintenance of Homeostasis - prevents excessive loss of water and electrolytes
3) Thermoregulation - affected by: > production of perspiration (dehydration fever) > activity > constriction (↓ dissipation of heat) and dilation of blood vessels > external BT ↔body’s core temperature
4) Reception of stimuli - area in the brain – SOMATOSENSORY CORTEX - abundance of free nerve endings and receptors * NOCICEPTOR - pain * END-ORGAN OF RUFFINI/PACINIAN CORPUSCLE - pressure * MECHANORECEPTOR - machanical * MEISSNER’S CORPUCLES (MERKEL DISCS/CELLS) - touch
5) Synthesis of vitamin D - helps the uptake of Ca2+ and PO4 in intracellular level - with the aid of sunlight activates Vitamin D to D3 (Cholecalciferol)
6) Immunity/processing of antigenic substances - immunologically mediated defenses against microorganisms Ex. Langerhans cells Keratinocytes
7) Provide an outward appearance or cosmetic adornment - acceptance of the appearance of the skin, hair, or nail is critical to psychosocial being
8) Excretion - skin has a vital role in elimination of Na+ and H2O for homeostasis (maintaining balance in the internal environment)
STRUCTURES OF THE SKIN
LAYERS OF THE SKIN
1) EPIDERMIS – avascular in nature - Thickness: 0.04 mm (eyelids- thinnest) to 1.6 mm (palms and soles- thickest)
4 Cell types of the Epidermis
a)