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“It is only the ignorant who despise education.”. The Integumentary. System. Chapter 4. I. Beneath the skin- HYPODERMIS. A. Loose connective and adipose tissue 1. Half the body’s stored fat. II. SKIN. A. DERMIS- two layers 1. Reticular layer - dense connective tissue
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The Integumentary System Chapter 4
I. Beneath the skin- HYPODERMIS • A. Loose connective and adipose tissue 1. Half the body’s stored fat
II. SKIN • A. DERMIS- two layers • 1. Reticular layer- dense connective tissue • a. collagen and elastin-makes the skin strong and elastic • b. cleavage lines • 2. Papillary layer • a. contains blood vessels- supplies epidermis • b. forms finger and footprints
B. EPIDERMIS • 1. Made out of layers called STRATA (stratum) • 2. Bottom layer- Stratum Basale • a. much cell division • 3. Top layers- Stratum Corneum • Dead, keratinized cells • Keratinization- cells die and change chemically to form a protective barrier • 25 or more layers • Dandruff, callus, corns
C. Skin Color • 1 The main skin pigment is MELANIN • 2. It is produced by cells in the stratum basale called MELANOCYTES • a. melanin also produces freckles and moles • b. albinos- no melanin • c. birthmarks- congenital, disorder of capillaries in dermis
D. Accessory Skin Structures • 1. Hair • a. hair is dead, keratinized epithelial cells • Hair shaft and hair root • b. hair is produced in the hair bulb (part of the hair follicle), which rests on a papilla in the dermis • c. growth stage and resting stage • Hair is held during resting stage, when next growth stage begins, the old hair falls out • d. hair color- mostly due to melanin
2. Arrector Pili Muscles a. insulates animals • 2. Arrector Pili Muscles • a. insulates animals
3. Glands • a.sebaceous (oil) glands • Produce sebum (oil), which prevents drying and inhibits some bacteria • b. sweat glands – 2 types • Eccrine sweat glands • Located everywhere • Sweat is water and salts • Cools the body • Also released during stress
Apocrine sweat glands • Location: attached to hair in axillae and genitalia • Sweat is organic and odorless • Combined with bacteria produces body odor
4. Nails- made out of dead stratum corneum and very hard keratin • a.nail body- visible part of nail • b. nail root- covered by skin • C. cuticle-stratum corneum • d. Nail matrix- under proximal end of nail • Nail growth • e.. lunula- visible part of nail matrix
III. Functions of the Integumentary System • A. Protection-water loss, microbes, abrasion • B. Temperature regulation • C. Vitamin D production • 1. Used by bones and muscles • D. Sensation- sensory receptors in dermis and epidermis • E. Excretion- small amount of waste
IV. The Effects of Aging • A. blood flow to skin reduced • 1. Skin becomes thinner and transparent • 2. Less collagen- easily damaged • 3. Less elastin and fat (hypodermis)-wrinkles • 4. Age spots, gray hairs
V. Burns • A. 1st degree- epidermis only • B. 2nd degree- epidermis and part of dermis • C. 3rd degree- epidermis and dermis are completely destroyed • D. Healing
VI. Skin Cancer • A. Basal cell carcinoma (most frequent) • 1. Begins in stratum basale and goes into dermis • 2. Treatment- surgery or radiation • 3. Does not metastasize
B. Squamous cell carcinoma • 1. Cells above stratum basale • 2. Can get into dermis, metastasize and cause death • C. Malignant melanoma (rare) • 1. From melanocytes in a mole • 2. Can metastasize and cause death
VII. Diseases of the Skin • A. Acne • 1. Infection involving Hair follicles and sebaceous glands • B. Viral infections • 1. Carried to skin by blood • a. measles, rubella, chicken pox, • C. Warts and cold sores (herpes)- also caused by viruses • D. Eczema and dermatitis