The Integumentary System INTEGUMENTARY SYSTEM Structure Epidermal layer
- Slides: 21
The Integumentary System
INTEGUMENTARY SYSTEM Structure - Epidermal layer, Dermal layer, Subcutaneous layer v Functions A. Regulation of body temperature – sweat, vessels dilate for heat loss/heat retention through vessel constriction B. Protection – keeps water and other molecules in, keeps water and undesirable substances out C. Sensation – detect pain, pressure, temperature, touch v D. Excretion – elimination of some nitrogenous waste, excess salt, water (sweat/perspiration E. Immunity - macrophages F. Synthesis of Vitamin D – sunlight hits skin cells, cholesterol is converted to precursor molecule that aids in
EPIDERMIS – Stratified squamous epithelium, first layer of skin Cell Types: a. KERATINOCYTES – in all five layers, more on the outside, make keratin, sealing cells b. MELANOCYTES – Produce melanin c. LANGERHANS CELLS – macrophages d. MERKEL CELLS – sensory cells
First Layer of the Integumentary System v Epidermis v Five layers of Strata from deepest to most superficial a. Stratum Basale – (Germinativum) – deepest, single layer of cells, only layer to undergo mitosis (millions of new cells daily) receives adequate nourishment, contains few keratinocytes, melanocytes, Merkel cells, as are pushed out become more keratinized,
b. Stratum Spinosum contains keratinocytes, Langerhans cells arise in the bone marrow and migrate receives nourishment several layers thick does not divide c. Stratum Granulosum – 3 -5 layers of flattened keratinocytes = water repellent last living layer, receives nourishment everything beyond this layer is dead
d. Stratum Lucidum Few layers of dead keratinocytes Found only in thickskinned areas (pads of feet, palms of hands, calluses – no hair e. Stratum Corneum 20 -30 layers thick of dead keratin-filled cells, protects against abrasion and penetration, water proof
Second Layer of the Integumentary System v Dermis 1. Cells of dermis – fibroblasts, macrophages, adipocytes. 2. Thick – palms, soles/Thin – scrotum, eyelids 3. Dermal Papillae – produce fingerprints, contain tactile receptors called “Meissner’s
Dermis cont. 4. Lower Region of the Dermis a. Consists of dense, irregular connective tissue containing collagen and elastic fibers, adipose tissue, hair follicles, nerves, oil glands, and the ducts of sweat glands. b. These fibers give skin it’s strength! Extensibility – ability to stretch (ex. neck, elbow “chickenskin”) Elasticity – the ability to return to it’s original shape after extension or contraction (ex. Pregnancy, Tissue swelling) c. Lamellated Corpuscles – a subcutaneous layer that is sensitive to pressure
Skin Color and Pigmentation A. Pigments 1. Melanin – pigment in the epidermis 2. Carotene – pigment in the dermis 3. Hemoglobin – pigment in the RBC’s ( passes through capillaries in the dermis)
Malignant Melanoma 1. Melano = dark colored; oma = tumor 2. Cancer of the Melanocytes 3. Due to the repeated exposure of ultraviolet radiation – amount of darkness of melanin increases
Hair 1. Primary function is protection, guards the scalp from injury and the sun’s rays a. Eyebrows and Eyelashes – protects the eyes from foreign particles b. Nostril hair – protects against inhaling insects and foreign particles
Hair - Composition v Hair is Keratinized cells, that consist of a shaft and a root. a. SHAFT – projects above the surface of the skin. b. ROOT – below the surface that penetrates into the dermis and into the subcutaneous layer. c. HAIR FOLLICLE – composed of two layers of epidermal cells : External and Internal root sheaths surrounded by a connective tissue sheath.
Anatomy of the Hair Follicle:
More Hair Composition!!! d. BULB – onion shaped structure, contains papilla of the hair, which have many blood vessels and provide nourishment for the hair. e. MATRIX – included in the bulb, produces new hairs by cell division when older hairs are shed.
Growth cycles of the hair. a. GROWTH STAGE – Cells of matrix differentiate Keratinization Death *New cells are added at base of root making the hair grow longer. b. RESTING STAGE – Growth of the hair stops, innactive matrix and shortening of hair follicle. c. NEW GROWTH CYCLE – *New hair replaces old hair and old hair is pushed out of the growth cycle.
v Melanin –hair color is due to melanin (brown, black, blonde). **FYI – decreased melanin production and increased air in the hair shaft produces grey and white hairs. v Goosebumps - due to the contraction of the arrector pili, under stresses of fright and cold which pull hairs into a vertical position.
Glands 1. Sebaceous Oil Glands – secreting portion lies in the dermis and open into the necks of hair follicles or directly onto a skin surface. *no sebaceous glands on the palms or soles a. Sebum – oily secretion that …. - Keeps hair from drying out and keeps skin soft - Prevents excessive evaporation of water from skin
BLACKHEADS – accumulated sebum and enlargement of sebaceous glands in face. PIMPLES – sebum acts as a nutrient to bacteria – leads to formation of pus
2. Sudoriferous (Sweat) Glands – Two types a. Eccrine sweat glands– more watery secretion during emotional stress or “cold sweat. ” - Palms, soles and forehead b. Apocrine sweat glands- axillary and urogenital - Secretions along hair follicles c. Ceruminous glands- external ear canal - Secretes cerumen (ear wax) - Hair and ear wax provides barrier against debris d. Mammary glands- specialized sweat gland - Production of milk
Nails 1. Structure - Plates of tightly packed, keratinized cells of the epidermis. a. NAIL BODY – visible portion of nail (PINK PART) b. FREE EDGE – part that extends past the end of the finger or toe. c. NAIL ROOT – non-visible portion d. LUNULA – thickened, whitish semilunar area Near the nail root and cuticle
2. Growth of the nails a. Occurs by transformation of superficial cells of the nail matrix into nail cells. b. Growth slower in toenail. c. The longer the digit the faster the nail grows d. The more the hand is used, the faster the nail growth. e. Nails help us grasp and manipulate objects and provide a protection against damage to the fingertips.
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