1. Integumentary System Chapter 5
From Essentials of Anatomy & Physiology,
Seeley, Stephens, and Tate, 5th Edition, 2005,
McGraw Hill Companies

2. Functions Protection against abrasion and ultraviolet light
Protection from entry of microorganisms and dehydration
Sensation receptors for heat, cold, touch, pressure, and pain
Production of precursors to Vitamin D when exposed to
ultraviolet light
Regulation of temperature by controlling blood flow to the skin
and activity of sweat glands
Excretion of waste products through the skin and the gland
secretions

3. The study of the integument is called dermatology.
Facts
The integumentary system consists of the skin and the structures derived from it including hair, nails, and glands.
The skin is the largest organ of the body, covering approximately 2 square meters and having a mass of about 5 kilograms.
The study of the integument is called dermatology.

4. Anatomy of Skin
Epidermis - the five outermost thin layers, mitosis in the deepest layer produces new cells as the older cells move towards the most superficial layer where they are sloughed off
Dermis - the thicker layer below the epidermis containing blood vessels, nerve endings, hair follicles, smooth muscles, lymphatic vessels, sweat glands, and sebaceous glands
Hypodermis - the layer of loose connective tissue under the dermis and not considered part of the skin, it contains half of the body’s stored fat which acts as padding and insulation, it attaches to underlying bones and muscles

5. This image shows the
epidermis partially
peeled away
from the dermis.
Note the numerous
blood vessels extending
into the dermis from the
hypodermis.
Note the fat in the

6. This is a micrograph of actual skin sliced thinly and stained.
Note the epidermis, dermis, and hypodermis. The outer cells of the epidermis are sloughing off.
The dermal papillae are projections of the dermis which extend into the epidermis. They contain tiny blood vessels that supply the epidermis and aid in regulation of body temperature.
Fingerprints are projections of the dermal papillae into the epidermis of the fingertips. They increase friction and help improve grip.

7. This image shows the five layers of the epidermis.
The outermost layer is called the stratum corneum:
-25 layers of dead skin cells
-Keratinized
Keratin is a protein that builds up in cells of the epidermis as they move from the deepest layer, the stratum basale, towards the skin’s surface. This process is called keratinization and takes 2-4 weeks.

8. Epidermal Layers - Blisters, Calluses &Psoriasis
Composed primarily of keratinized stratified squamous
epithelial cells -- consisting of 4-5 layers:
stratum corneum: outermost layer, keratinized dead epithelium
stratum lucidum: layer found in thickest areas of skin
stratum granulosum: 3-5 layers of flattened granular cells, developing keratin fibers
stratum spinosum: multiple layers of cells
stratum basale: deepest layer of single cuboidal or columnar cells, also contains melanocytes
- Blisters, Calluses &Psoriasis

9. Skin Color - Genetics, Environment & Physiology:
# of melanocytes - difference in kind, amount & size
sunlight, UV light, etc.
blood in dermis, blood vessels, freckles & moles
other pigments - carotinoids
jaundice – liver disorder

10. Skin, hair, and eye color are all due to a molecule called melanin
Skin, hair, and eye color are all due to a molecule called melanin. This provides protection from the sun’s ultraviolet rays.
Melanin is made by special cells in the stratum basale called melanocytes which have extensions reaching towards the skin’s surface. Note the pigment granules in these cell extensions.

11. Variations in skin color are due to the color, amount, and distribution of melanin, not to the number of melanocytes present in the epidermis.

12. Special Features of the Dermis
Hair follicles - hair grows from hair bulbs in the follicle, the follicles are actually extensions of the epidermis deep into the dermis
Arrector pili (muscles) - an arrector pili muscle is associated with each hair follicle, when the muscle contracts the hair stands on end, contraction of these muscles also causes goose bumps
Sweat glands - sweat is produced in these coiled glands and is secreted on the skin’s surface through pores, sweat is sometimes produced due to emotional stress but is usually produced in order to decrease body temperature by evaporative cooling
Sebaceous glands - most sebaceous glands are connected to hair follicles and produce an oily substance called sebum, the sebum protects against drying of the hair and skin and against some bacteria

13. Skin Glands Sweat glands:
Sebaceous glands:
- assoc. w/ hair follicles,
secrete sebum - oils hair,
lubricates skin & prevent
water loss
- acne vulgaris
Sweat glands:
Eccrine: deep in dermis or subcutaneous layer, odorless secretions, function in thermoregulation
Apocrine: found near hair follicles, in axillary regions, released during pain, fear & stress or sexual arousal
- Ceruminous & mammary glands

14. Note the extension of the epidermis far into the dermis forming the hair follicle. Also, note the coiled sweat gland and the sebaceous gland connected to the hair follicle.

18. Nails

21. Wound healing