Chapter 4 Integumentary System

-skin, nails, sweat glands, and sebaceous glands -integument is the largest orgain -1.5 - 2 square meters! -skin account for 7-8% of body weight thickness ranges from 1.5-4 mm

-protection (chemical, physical, and biological barrier) -prevents loss of water -temperature regulation -metabolic regulation -immune defense -sensory receptors -excretion by emans of secretion (sweat)

Epidermis -epithelial tissue -avascular Dermis -connective tissue -vascular Hypodermis -NOT a part of the integument -Connective tissue -VASCULAR

Keratinized Stratified Squamos eptithelium layers -Stratum Corneum -Stratum Lucidum (thick skin only) -Stratum Granulosum -Stratum Spinosum -Stratum BAsale (germinativum)

Keratinocytes -most abundant -produce keratin -found in ALL layers Epidermal Dendritic Cells (LANGAERHANS) -macrophages in immune response -stratum spinosum Tactile Cells (MERKEL) -sensory receptors -stratum basale (root of tissue)

Hemoglobin- -found in blood, causes pink hue in caucasian Melanin -produced by melanocytes -UV exposure darkens existing melanin and stimulates melanocytes Carotene -Found in plantes, yellow to orange pigment

Nevus, Mole, or Brithmark -overgrowth of melanin-forming cells -harmless unless it mutates and becomes malignant Freckles -Yellowish or brown spots frome xcessive mlanocyte acitvity, not increased melanocyte cells Hemangioma -Congenital Anomoly -port-wine stains Friction Ridges -formed by epidermal ridges and dermal papilae -fingerpritns -patterns are well-formed by the 4th month of fetal development

Two layers: -papillary layers (areolar CT) -reticular layer (dense irregular CT) Epidermal Ridges Dermal Papillae

Striae (stretch marks) which is TORN collagen Wrinkles- caused by age and UV exposure -decreased flexibility and thickness of dermis Cleavage Lines-Orientation of collagen bundles

Areolar and adipose connective tissue anchors sin to underlying structures allows skin to slide freely (FAT) larger in women...

Scale like modifcation in epidermis contains hard KERATIN grows from nail matrix

Hair is everywhere!!! except for palms, soles, lips, sides of fingers an toes, and parts of the extermal genitalia Functions: -protects from the sun -senses touch -reduces heat loss

Lanugo:fine downy hair on fetuses Vellus: hair on arms and legs -fine hair Terminal: hair on head, pubic region, and men's facial hair (thick stuff)

Consists of root and shaft Arrector pili muslce (when you get scared!) RAte of hair growth 2 mm/week growth cycles - active (2-5 years) and dormant pahses (3-4 months)

Diffuse of hair Loss male Pattern Baldness -genetic and hormonal influences -baldnes gene is in MALES -testosterone causes terminal hair to be replaced be VELLUS HAIR Alopecia-spot baldness