Skin and Glands

epidermis

outermost layer of skin

dermis

middle layer of skin; innervated and vasculated

hypodermis

the layer of skin beneath the dermis, which serves as a storage repository for fat

keratin

hard protein material found in the epidermis, hair, and nails

melainin

brown, yellow-brown, or black pigment produced by melanocytes

tactile cells (merkel cells)

sensory touch receptors

stratum basale (germinativum)

deepest, mitotic layer of the epidermis

stratum spinosum (prickly Layer)

second deepest layer of the epidermis; 7-10 layers of cells, mostly keratinocytes with a few langerhans cells and some melanin granules

stratum granulosum (granular layer)

third layer from the bottom of the epidermis; composed of cells that look like granules and are filled with keratin; replaces cells shed from stratum corneum

stratum lucidum (clear layer)

only in thick skin; thin, translucent band superficial to the stratum granulosum

A few rows of flat, dead keratinocytes

stratum corneum (horny layer)

uppermost layer of the epidermis; 20 to 40 cell layers of dead, flat keratinized cells, accounts for up to 3/4s of epidermal thickness.

dermal papillae

a fingerlike projection of the dermis that may contain blood capillaries or Meissner corpuscles (of touch)

cleavage lines (tension lines)

many collagen fibers running parallel to skin surface; important to surgeons because incisions parallel to cleavage lines heal more readily

straie

stretch marks made in the collagen fibers of the dermis layer

blister

a bubble-like collection of fluid beneath or within the epidermis of the skin

cyanosis

a bluish discoloration of the skin resulting from poor circulation or inadequate oxygenation of the blood.

pallor (blanching)

pale color due to anemia, low blood pressure, fear, anger

erythemia

redness of the skin; may indicate fever, hypertension, inflammation, or allergy

juandice

yellowing of the skin, can indicate bile in the blood as a result of liver or gallbladder disease

suderiferous glands

sweat glands

eccrine or merocrine sweat glands

secreting glands, are far more numerous and are abundant on palms, soles of feet and forehead.

apocrine sweat glands

produce true sweat plus fatty substances and proteins; found in the axillary and anogenital areas of the body

ceruminous glands

modified sweat glands, located in external ear canal, secretes cerumen (earwax)

mammary glands

specialized organs in mammals that produce milk to nourish the young

sebum

oily substance secreted by sebaceous glands

sebaceous glands

secrete sebum (oil) into the hair follicles where the hair shafts pass through the dermis