Unit 3 Day 2 Anatomy Before everything else, getting ready is the secret to success. Henry Ford

Today’s Agenda Notes on Objective 1 Epidermis Practice labeling skin Notes on objective 2

Epidermis is Keratinized Stratified Of 4 cell types

Epidermis continued Keratinocytes- make keratin protein Melanocytes—make melanin Merkel’s cells – touch reception Langerhan’s cell – macrophage-like

Layers of Epidermis Totally new epidermis every days due to layering Stratum Basal—basal layer Deepest layer Single row of keratinocytes Some Merkel cells 25% melanocytes Much mitosis

Stratum Spinosum (spiny layer) Several cell layers thick Little mitosis Keratinocytes with spine-like projections Langerhan’s cells present

Stratum Granulosum (granular layer) Very thin, 2-3 layers of flattened cells Granules of keratohyalin give its name Keratinization begins here, as lower cells rise to this layer, die and leave keratin later to be abraded away.

Stratum lucidium (clear layer) found only in really thick skin Thin layer with keratohyalin and tonofilaments.

Stratum Corneum (horny layer) Broad layer, cell layers thick All dead, keratinized cells.

1. Sebaceous gland 2. Root of the hair 3. Epidermis 4. Dermal Papilla 5. Arrector pilli 6. Dermis 7. Bulb of the hair 8. Hair follicle

1. Covering of follicle 2. External root sheath 3. Internal root sheath 4. Cortex 5. Bulb of the follicle 6. Adipose tissue

Spider bite

Ringworm fungus

Acne

Fig. 38.3, p. 646 hair EPIDERMIS DERMIS hypodermis (subcutaneous layer) oil gland hair follicle blood vessels sensory neuron sweat gland smooth muscle