Bio Exam 2 Part 3

Chapter 5 Integumentary System Part 3

Endocrine Functions and the skin and healing

Hormones coordinate integumentary system function with other systems Part 1

Steroid hormones (glucocorticoids) Loosen intercellular connections and reduce epidermis effectiveness as a barrier to infection. Thyroid Hormones Maintain normal blood flow to papillary plexus

Hormones coordinate integumentary system function with other systems Part 2

Epidermal Growth Factor (EGF) Peptide that has widespread effects on epithelia Produced by salivary glands and glands in duodenum

Growth Hormone and Sex Hormone

Growth hormone Stimulates fibroblast activity and collagen production Stimulates germinal cell division Thickens epidermis Wound repair

Sex Hormone Increase epidermal thickness Accelerate wound healing Increase number of dendritic cells

Production of Vitamin D

Sunlight UV radiation causes epidermal cells to convert into cholecalciferol Liver creates products to then convert to calcitriol by kidneys Diet Fish Fortified food products

Vitamin D Deficiency in children

Rickets Poorly mineralized bones

Skin Repair Part 1

Initial injury Bleeding Mast cells cause inflammation After 7 hours Blood clot (scab) forms Macrophages patrol Stratum Basale cells divide and migrate to wound Granulation tissue forms after one week Parts of blood clot dissolve Fibroblasts create collagen fibers

Skin Repair Part 2

After several weeks Scab sheds Epidermal repair completes Scar tissue created by fibroblasts raise up epithelium

Keloid

Raised thickened mass of scar tissue Grows into surrounding dermis Most often in dark-skinned adults

Burns

Partial thickness First degree Second degree Full thickness Third degree Fourth degree affect deeper structures (skin grafts) Split skin Artificial skin Cadavers or pigs