Integumentary System: (SKIN)

Integumentary system: (SKIN) Functions 1. Physical protection from outside environment (skin) 2. Regulation of body temperature sweat gland, oils (antibacterial agents) 3. Excretion 4. Nutrition synthesizes vitamin D from sun light 5. Sensation touch 6. Coordinates immune defense

2 major components of the skin 1. Cutaneous membrane a. Dermis b. Epidermis

2. Accessory structures a. Hair b. Nails c. Glands

Epithelial, connective, muscle, nervous all found in the integument

Epidermis: Consists of keratinized stratified squamous epithelia 4 cell types- 1. Keratinocyte produces keratin (most abundant) water proofs 2. Melanocyte produces melanin (pigments) absorbs UV light 3. Merkel cells sensory nerve ending receptors 4. Langerhans cells phagocytic cells, against pathogens & epidermis cancer cells

Layers of epidermis: 1. Stratum germinativum (basal) -Attaches to basal lamina of basement membrane -Large stem cells or basal cells -Contain Melanocyte -Lack hair but have Merkel cells 2. Stratum spinosum (spiny) - Stem cells differentiation into keratinocyte - Several Layers thick - Keratinocyte tie together by desmosomes & tonofibrils - Langerhans cells present 3. Stratum granulosum (granular) - Keratinocyte displace from spinosum layer - Produce keratinocyte surrounds keratin filaments & keratinocyte begin to die 4. Stratum lucidum (clear)

- Found in thick skin of palms and soles of feet may or may not be present 5. Stratum Corneum - 15 to 30 layers thick flat dead cells - Cornified large amounts of keratin - Continually shed and replaced - Serves as a barrier against light and heat - Protection against bacteria & chemicals

Epidermis ridges- deep layers of epidermis extending into dermis

Dermal papillae- projection from dermis expanding into epidermis (fingerprints)

Skin color - Due to blood supply (blush) - Pigments (carotene, melanin) - Pink - capillaries

Dermis: - Lies deep to epidermis (2 Layers) a. Papillary layer contains capillaries, nerves, loose connective tissue b. Reticular layer blood vessels, hair, follicles, sebaceous glands, dense connective tissue

Nerve receptors of the skin: 1. Meissner’s corpuscles touch 2. Ruffini corpuscles stretching 3. Pacinian corpuscles deep pressure & vibration

Subcutaneous: - Hypodermis/superficial fascia - Loose connective tissue adipose - Not a “true” part of integument - Large arteries & veins - Baby fat

Accessory structures: - Hair, hair follicles, sebaceous, nails, sweat glands 1. Hair/ follicles protection, deep in dermis - Hair papilla root = shaft (hair) - Hair bulb, surrounds papilla

Arrector pili muscle - Smooth muscle, surrounds hair - Follicle makes hair stand up - Works with sebaceous glands in excreting sebum

Root hair plexus: - Sensory nerves, surrounding the base of each hair follicle Glands: - Sebaceous glands  produces sebum for protection and lubrication - Sweat glands a. Apocrine- axilla, aereola & groin = pheromones b. Eccrine/merocrine8i widely distributed produce sweat

Other Integument glands 1. Mammary 2. Ceruminous ear wax produces cerumen; extern, audit canal

Nails: a. Nail body- visible part b. Nail bed- under the body c. Nail root- nail production occurs

The Skin throughout Life

1. most skin aging is cause by the sun and is called photoaging. UV induced activation of enzymes which degrade collagen 2. liver spots 3. decline in collagen