Dermis Just deep to epidermis Two layers Collagen and elastin Papillary layer Reticular layer Collagen and elastin Dermal blood supply Nerve endings Some muscle tissue Glands Hair and nails

Papillary Layer Papillary Reticular Contains dermal papillae (hence papillary) Many capillary loops (feed the epidermis) Reticular Base of hair and nails Nerve endings Glands

Hair Anatomy Shaft – shows above skin Root – below / in the skin Follicle - where hair attaches and grows from (clear part when pulled out) Hair matrix – group of cells that cause growth of hair (they create more cells, causing the others to move upward = growth)

More hair…. The hair that you groom daily (shaft) is actually dead keratinized cells. Each hair follicle has an associated bundle of smooth muscle, the arrector pili muscle. This muscle inserts with one end to the papillary layer of the dermis and with the other end to the hair follicle. This makes your hair stand up on its end.

Hair Color and Texture – fun facts Hair color is determined by the amount and type of melanin present. Melanocytes become less active with age. Gray hair is a mixture of pigmented and non-pigmented hairs. Red hair results from a a modified type of melanin that contains iron. The shape of the hair shaft determines texture. Round shaft – straight hair Oval shaft – wavy hair Flat shafts – curly or kinky hair **Perms use chemicals to flatten shafts and makes hair curly. Alopecia is the term for hair loss.

Nails Plates of cells with hard keratin Protect distal ends of phalanges Cells are keratinized in the nail root Nail growth occurs in the lunula Nail matrix – group of cells responsible for growth The cuticle is a fold of stratum corneum on the proximal end of nail

Click here to copy and paste a Picture of the skin and nail here.

Glands Exocrine glands = “EXIT” the body “Ex”ocrine Sweat, Oil, Ear wax All that relate to skin Endocrine glands = release contents within the body hormones

Sebaceous glands They secrete the sebum (seb = oil) an oily product. Sebum is usually secreted into a hair follicle. Sebum is a natural skin cream: prevents excessive evaporation of water from the skin, keeps the skin soft contains a bactericidal agent that inhibits the growth of certain bacteria. Sebaceous glands are scattered all over the surface of the skin except in the palms, soles and the side of the feet.

Homeostatic Imbalance: Pimples = bacteria in oil glands Blackhead – sebaceous gland is blocked and the blockage dries up (oxidized) Whitehead – Sebaceous gland blocked / pus

Sweat Glands Eccrine – Found all over the body secretes directly to the surface of skin via pores Main function: evaporative cooling Apocrine – Activated during puberty Located in the axillary region, pubic region, and mammary region. Secrete onto hair follicle (unlike eccrine) A LOT stronger / potent than eccrine sweat glands

Other exocrine glands Mammary glands Ceruminous Glands Related to apocrine glands Secretes milk Triggered by hormones Ceruminous Glands Modified sweat glands Produce cerumen (ear wax) Helps trap foreign particle from entering

Sensory!! (nerve endings) Meissner’s corpuscles – (tactile) sensitive to light touch found in papillary layer Pacinian corpuscles – (lamellated) deep pressure and vibration found in reticular layer

More Fun Facts!! House dust is mainly skin flakes! If you laid out all your skin on a flat surface, it would have an area of about 2 square meters. Skin weighs about 2.5 kilograms - the largest organ in the body. What hurts if you pull it, but doesn't hurt if you cut it? Your hair, of course! Skin is elastic - it springs back into shape when stretched. Some medicines (estrogen, nicotine) can pass through the skin, but others cannot (insulin). Why is that? Because only fat-soluble substances can enter the skin, not water-soluble ones. Your hair stands on end and you develop 'goose bumps' because there are tiny muscles attached to the hair follicles and they contract when you are frightened or cold.