UNIT 3 THE INTEGUMENTARY SYSTEM. SKIN (1) copie 7.pdf

OUTLINE 3.4 Functions of skin Physical and chemical protection. Functions in HOMEOSTASIS: – Thermoregulation (blood reservoir). – Provides sensory information. – Secretion-excretion. – Synthesis of vitamin D. © Copyright Universidad Europea. Todos los derechos reservados PROTECTION Physical prot...

OUTLINE 3.4 Functions of skin Physical and chemical protection. Functions in HOMEOSTASIS: – Thermoregulation (blood reservoir). – Provides sensory information. – Secretion-excretion. – Synthesis of vitamin D. © Copyright Universidad Europea. Todos los derechos reservados PROTECTION Physical protection (wind, dehydration, UV, trauma): due to the pigments such as melanin, also lipids, keratin, GAGs… Chemical protection (detergents, cosmetics): due to the structure. Biological barrier to microorganisms: due to the intercellular junctions, Langerhans’ cells. © Copyright Universidad Europea. Todos los derechos reservados THERMOREGULATION Heat ↑ Perspiration and evaporation. Vasodilation (VD) of the superficial vascular dermal network. Exercise Moderate: Vasodilation (↑ blood flow in the surface, ↓ temperature). Extreme: blood is conducted to the muscles and body temperature increases. Cold: Vasodilation of the deep vascular dermal network, and ↓ perspiration and evaporation. © Copyright Universidad Europea. Todos los derechos reservados THERMOREGULATION Vasoconstrictors: ATP, anti-histaminic agents, angiostensin II, chatecholamines, norinephrine. © Copyright Universidad Europea. Todos los derechos reservados Vasolidators: Heparin, adenosine, NO, histamine, bradykinin. FUNCTIONS • Blood reservoir Extensive network of blood vessels. • Cutaneous sensations Touch, pressure, vibration, heat, cold, pain, tickle… • Excretion 400 mL of water/day, small amounts of salt, CO2, ammonia, and urea. © Copyright Universidad Europea. Todos los derechos reservados VITAMIN D SYNTHESIS • Synthesis of Vitamin D. UV light: activation of vitamin D precursor molecules in skin. Hepatic and renal enzymes modify the activated molecule to produce calcitriol (most active form of vitamin D). Function: It favors calcium absorption. CALCITRIOL © Copyright Universidad Europea. Todos los derechos reservados The acronym SHAPES to to remember the functions of the skin: Sensation. Heating & Cooling (Temperature Regulation) Absorption. Protection. Excretion. Secretion. © Copyright Universidad Europea. Todos los derechos reservados 67