| A | B |
|---|
| thick skin | skin—five layers; found on palms of hands and soles of feet |
| thin skin | four layers; found on the rest of body |
| Stratum germinativum (stratum basale) | deepest epidermal layer |
| Epidermal ridges | extend into dermis to increase are of contact between the layers |
| melanocytes | synthesize melanin |
| Stratum spinosum | layer of epidermis above the stratum germinativum |
| Stratum granulosum | layer of epidermis above stratum germinativum |
| Keratin | a protein that is extremely durable and water resistant, coats skin and forms basic structure of hair, nails, and calluses |
| Stratum lucidum | layer of epidermis found in thick skin |
| Stratum corneum | most superficial layer of epidermis, consists of 15-30 layers of flattened and dead epithelial cells |
| cornified | have accumulated large amounts of keratin |
| Carotene | contributes orange-yellow color to skin |
| Cyanosis | blood in the skin turns dark red and then blue due to sustained reduction in circulatory supply |
| Benefits of UV radiation | Activates synthesis of vitamin D3 |
| Harmful effects of UV radiation | sun burn, wrinkles, premature aging, cancer |
| Malignant melanoma | cancerous melanocytes grow rapidly and metastasize through the lymphatic system |
| Basal cell carcinoma | non-malignant tumor in stratum germinativum |
| Squamous cell carcinoma | tumor in superficial layers of epidermis |
| Papillary layer | layer of dermis that consists of loose connective tissue that supports and nourished the epidermis |
| Reticular layer | layer of dermis that consists of interwoven mesh of dense, irregular connective tissue |
| hypodermis | subcutaneous layer |
| Hair | non-living structures found everywhere on body except bottoms of feet & palms, lips, sides of fingers & toes, and parts of the genitals |
| Hair follicle | structure that produces hair; projects deep into the dermis, walls contain epidermal cells layers |
| hair papilla | site in the hair follicle where new hair starts to form |
| Hair root | anchors hair to the skin |
| Hair shaft | the part of the hair we see above the surface; consists of three layers of dead, keratinized cells |
| Arrector pili | smooth muscle cells; contracts and causes hair to stand up |
| Sebaceous glands | holocrine glands that discharge an oily lipid secretion into hair follicles or onto skin |
| Sebum | secretion, lubricates hair and skin and inhibits the growth of bacteria |
| Sweat Glands | sudoriferous glands |
| Apocrine sweat glands | produce odorous secretion (“funky”), absent before puberty, present in axilla, areola, & groin |
| Merocrine sweat glands | secrete watery sweat (~1% NaCl) directly onto skin, widely present in skin; helps the body cool when sweat evaporates off of the skin |
| Nail body | dense mass of keratinized cells, covers nail bed |
| Nail root | area of nail production |
| Cuticle | eponychium |
