1. Integumentary System
Chapter 5

2. Skin Color

4. Skin Pigments: Melanin Carotene Hemoglobin
Two forms: brown-black & pink-red
Made by melanocytes
Only found in deeper layers of epidermis
Freckles & moles = local accumulations of melanin
Protect DNA from UV radiation
Carotene
Yellow-orange (from carrots)
Accumulate in stratum corneum, hypodermis
Carotene converts to Vitamin A in body
Asians: yellowish skin = melanin + carotene
Hemoglobin
Pinkish hue
Red blood cells in capillaries

5. Homeostatic Imbalances
Cyanosis: poorly oxygenated blood, blue color
Excessive sun exposure: leathery skin, rashes, skin cancer
Redness: blushing, fever, allergy, inflammation, hypertension (high BP)
Pale skin (pallor): anemia, low blood pressure, fear, anger
Jaundice (yellow cast): liver disorder (bile pigments = bilirubin)
Bronzing: Addison’s disease, pituitary gland tumors
Bruises: blood clots under skin

6. Appendages of the Skin

7. Sweat glands (Sudoriferous)
Two types:
Eccrine sweat glands: releases sweat (99% water, salts, vitamin C, antibodies, wastes)
Abundant on palms, soles of feet, forehead
Evaporative cooling
Apocrine sweat glands:
Sweat + fatty substances & proteins  milky/yellowish
With bacteria = body odor
Activated at puberty  sexual scent gland?

8. Sebaceous glands Secrete oil (sebum) into the hair follicle
Waterproofing skin
Soften & lubricate hair, skin
Kills bacteria

9. Accessory Skin Structures: Glands
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Sebaceous Glands
Holocrine (death of secretory cells)
Oily secretion = sebum
Prevents drying and may inhibit bacteria
Most empty into hair follicle
Exceptions: lips, meibomian glands of eyelids, genitalia
Sweat pores
Duct of eccrine
sweat gland
Duct of
apocrine
sweat gland
Arrector pili
(smooth muscle)
Hair follicle
Sebaceous gland
Eccrine
sweat gland
Hair bulb
Apocrine
sweat gland

10. Accessory Skin Structures: Glands
Ceruminous glands: modified merocrine sweat glands, external auditory meatus.
Earwax (cerumen). Composed of a combination of sebum and secretion from ceruminous.
Function- In combination with hairs, prevent dirt and insects from entry. Also keep eardrum supple.
Mammary glands: modified apocrine sweat glands. Covered with reproductive chapter.

11. Hair (pili) 2 main regions: hair root & hair shaft
Project from follicles in dermis
Consists of dead, keratinized cells
Arrector pili (smooth muscles) attached to hair root  pulls hair upright

13. nails Grows from nail matrix Visible part of nail is nail body
Cuticle covers nail root
Contains hard keratin

14. Accessory Skin Structures: Nails
Anatomy
Nail body: stratum corneum
Eponychium or cuticle is corneum superficial to nail body, hyponychium is corneum beneath the free edge
Matrix and nail bed: cells that give rise to the nail
Nail root: extends
Growth
Grow continuously unlike hair
Fingernails grow mm/day; faster than toenails
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Free edge
Nail body
Nail groove
Nail fold
Nail body
Nail fold
Nail groove
Lunula
Bone
Cuticle
Epidermis
(b)
Nail root
(a)
Cuticle
Nail root
(under the skin)
Nail body
Nail
matrix
Free edge
Hyponychium
Nail bed
Bone
Epidermis
(c)

15. 5.5 Physiology of the Integumentary System
Protection
Against abrasion, sloughing off of bacteria as desquamation occurs.
Against microorganisms and other foreign substances. Glandular secretions bacteriostatic and skin contains cells of the immune system.
Melanin against UV radiation.
Hair on head is insulator and protection against light, and from abrasion. Eyebrows keep sweat out of the eyes; eyelashes protect eyes from foreign objects. Hair in nose and ear against dust, bugs, etc.
Nails protect ends of digits, self defense.
Acts as barrier to diffusion of water.

16. Physiology of the Integumentary System
Sensation: Pressure, temperature, pain, heat, cold, touch, movement of hairs.
Temperature Regulation: sweating and radiation.
Sweat causes evaporative cooling.
Arterioles in dermis change diameter as temperature changes. More or less blood flows through the dermis.

17. Physiology of the Integumentary System
Vitamin D Production
Begins in skin; aids in Ca2+ absorption.
Vitamin D (calcitriol): hormone.
Functions of Ca2+
bone formation, growth, repair
clotting
nerve and muscle function.
People in cold climates and those who cover the body can be deficient, but calcitriol can be absorbed through intestinal wall.
Sources: dairy, liver, egg yolks, supplements.

18. Physiology of the Integumentary System
Excretion
Removal of waste products from the body.
Sweat: Water, salt, urea, ammonia, uric acid.
Insignificant when compared with kidneys.

19. Whitehead = blocked sebaceous gland
Blackhead = sebum oxidizes and dries

20. Acne = active inflammation of sebaceous glands caused by bacterial infection (staph)
Treatment:
Reduce oil production
Speed up skin cell turnover (prevent plugged follicles)
Fight bacterial infection
Reduce inflammation