5. Figure 5.2: The main structural features in skin epidermis, p. 154. Sensory nerve ending Melanocytes Melanin granules Merkel cell Langerhans’ cell Stratum corneum Stratum granulosum Stratum spinosum Stratum basale Dermis Dermis Cells are dead; represented only by flat membranous sacs filled with keratin. Glycolipids in extracellular space. Cells are flattened; organelles deteriorating; cytoplasm full of lamellated granules (release lipids) and keratohyaline granules. Cells contain thick bundles of intermediate filaments made of pre-keratin. Cells are actively mitotic stem cells; some newly formed cells become part of the more superficial layers. Keratinocytes Desmosomes (b) (a)
24. Figure 5.4 Hairs = Pili Produced by cells in the MATRIX inside hair follicles Each hair has 2 regions – shaft and root SHAFT – region exposed above the skin ROOT – region below the skin enclosed by the hair follicle
25. Hairs = Pili Produced by cells in the MATRIX inside hair follicles Each hair has 2 regions – the shaft and the root SHAFT – region exposed above the skin ROOT – region below the skin enclosed by the hair follicle Matrix
26. Figure 5.5c-d: Structure of a hair and hair follicle , p. 161. Hair shaft Arrector pili Sebaceous gland Hair root Hair bulb in follicle Hair root (cuticle, cortex, medulla) Internal epithelial root sheath External epithelial root sheath Connective tissue root sheath Hair matrix e Hair papilla Subcutaneous adipose tissue Medulla Cortex Glassy membrane (d) (c)
27. Figure 5.5a-b: Structure of a hair and hair follicle, p. 161. Hair shaft Arrector pili Sebaceous gland Hair root Hair bulb in follicle Connective tissue root sheath Follicle wall Cuticle Cortex Medulla Internal epithelial root sheath External epithelial root sheath Glassy membrane (a) (b) 2 regions – shaft and root SHAFT – region above the skin ROOT – region below the skin enclosed by the hair follicles
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30. Figure 5.6: Structure of a nail , p. 163. Free edge of nail Body of nail Lateral nail fold Lunula Eponychium (cuticle) Nail matrix Root of nail Proximal nail fold Eponychium (cuticle) Body of nail Nail bed Free edge of nail Hyponychium Phalanx (bone of fingertip) (a) (b)
Largest internal organ is the liver Largest in general is the skin Hypodermis is part of the fascia – binds dermis to the skeletal muscle
Areolar connective tissue, dense regular connective tissue in dermis
Most skin is of the thin type… thick skin in soles of feet and palms 4 types of layers in thick skin (the list above is from deepest to most superficial)
Abutting basal membrane **FUNCTION OF MELANIN – protective function
3-5 layers of cells Cells contain tonofilaments (intermediate filaments) Cells are connected by desmosomes Contains epidermal dendritic cells (Langerhans’ cells) that act as macrophages
Started listening to the lecture here, seems like she’s been covering slides word for word
Glycolipids make it waterproof You lose 20,000 cells per minute! You lose 40 lbs of skin in a lifetime
Surface of dermis is saturated with blood vessels and nerve endings Meissner’s Corpuscles and Merkel cells both act as TOUCH RECEPTORS
Notice that dermis is much thicker than the epidermis
Release sweat as exocytosis
Apocrine name is a MISNOMER. Merocrine mode of secretion is used.. WATCH OUT FOR THIS
Ear drum surface kept moist by cerumen
To cure acne, you need to take an antibiotic
Derived from BASAL EPIDERMIS… look at slide 16
Hair is for protection Hair matrix highly vascularized
Alopecia – ALL the hair on your body is falling out and the rate of growth can’t keep up