| Term | Definition |
| Functions of the Skin | -Protection
-Temperature Regulation
-Sensation
-Excretion
-Synthesizes Vitamin D
-Absorption |
| Protection (Body's first line of defense) | -Infection by microbes
-Ultraviolet rays from sun
-Harmful chemicals
-Cuts and tears |
| Temperature Regulation | Controlled by: sweating/shivering |
| Sensation | -Functions as an enormous sense organ
-Keeps the body informed of changes in its environment |
| Excretion | Assists our body in excreting urea (a breakdown of protein) and other wastes |
| Synthesizes Vitamin D | When skin is exposed to UV light, a substance in skin cells is transported to the liver and kidneys where it is converteed into an active form of vitamin D |
| Absorption | Our skin can absorb mostly anything we plaace on it through passive diffusion; medications, toxins, creams. |
| Layers of the Skin | -Epidermis
-Dermis
-Hypodermis |
| Primary Skin Layers | Epidermis; avascular, outermost layer of the skin..
Dermis; deeper layer of the skin and much thicker, composed mostly of connective tissue
Hypodermis; tissue that lies beneath the skin, insulates and helps with body temperature |
| Epidermis | -Outermost layer of the skin
-Non-Vascular (no blood vessels present)); nourished by the dermis layer below |
| This layer of skin has cells that produces the pigment melanin | Epidermis |
| 5 Distinct Layers of Epidermis | -Stratum corneum
-Stratum lucidum
-Stratum granulosum
-Stratum spinosum
-Stratum basale |
| Epidermis facts | -95% of cells are keratinocytes; produce a tough fibrous protein, keratin (acts like a waterproof coating to prevent water loss)
-Gives skin that tough, abrasive resistant protective layer
-5% of cells are melanocytes (produces melanin) |
| Dermis | -20 times thicker than the Epidermis layer of the skin
-Composed mostly of connective tissue
-Mechanical strength of the skin is in this layer |
| Dermis: 1. Some fibers are tough and strong;
2. Some fibers are stretchable; | 1. Collagen
2. Elastic |
| Two layers of the Dermis | 1. Papillary
2. Reticular |
| Papillary Layer | -Consists of parallel rows of tiny bumps (dermal papillae)
-Forms ridges and grooves that make up fingerprints & footprints
-Pain & touch receptors are found here |
| Papillary Facts | -Ridges develop before birth
-Unique to each individual
-Purpose is to improve our grip when using tools, or walking on smooth surfaces |
| Reticular Layer | -Deepest skin layer
-Filled with a dense network of interlacing fibers |
| Reticular layer contains: | Blood vessels, sweat & oil glands, lymphatic vessels, and hair follicles
Pacini corpuscles (deep pressure receptors) found here |
| Hypodermis | Foundation layer, often referred to as: subcutaneous tissue
superficial fascia.
-Attaches skin to underlying tissues
-Spongy nature determines the relative mobility of the skin |
| Fact: *blank* is not always considered part of the integumentary system | Hypodermis |
| Hypodermis is mostly made up of: | Adipose tissue that stores fat for energy, provides insulation for temperature control and offers a soft cushion for protecton |
| Accessory Organs of the Integumentary System | -Hair
-Nails
-Glands |
| Hair | Hair root - lies hidden in follicle
Hair shaft - is the visible part
Hair papilla - small cap shaped cluster of cels, located at base o fhair follicle, nourished by dermal blood vessels |
| Arrector Pili | Muscle attached to hair follicle, contract when frightened or cold |
| Hairless areas of the body | Lips, palms of hands, soles of feet |
| Nails | Produced by epidermal cells, and made of keratin, which is hardened and plate-like
Nail body - visible part
Nail root - lies in a groove, hidden by cuticle
Lunula - crescent shaped area nearest root |
| Skin Glands | 1. Sweat (sudoriferous) glands
2. Oil (sebaceous) glands |
| Sweat/Sudoriferous Glands | Eccrine and Apocrine |
| Eccrine | -Produces perspiration, thin watery liquid
-Assists in elimination of waste
-Aids in temperature control
-We can see these (pores) |
| Apocrine | -Larger than eccrine sweat glands
-Mostly found in genitals, axillary areas
-Secretes yellowish, thicker substance
-Grow & function at puberty |
| Oil Glands | -Secrete oil for skin & hair
-Tiny ducts of these glands open into hair follicles, lubricating hair & skin
-Sebum (prevents drying & cracking *skins natural cream)
-Accumulates in and enlarges some of the ducts forming white pimples. |
| What increases in production at puberty, and decreases in late adult hood? | Oil/Sebaceous Glands |
