A&P Ch. 5 Integumentary

What are the skins functions?

protects against disease because it protects against particles, sensory response, formation of vitamin d, maintain body temperature, waste exchange (sweat glands)

What is psoriasis?

Skin cells grow too quickly and new skin cells form in days instead of weeks and it piles up because it cant shed the new cells.

Why is the stratum corneum thick? How often is it replaced?

Stratum corneum is thick because it is on the exposed skin surfaces. It is replaced every 2 weeks.

Which layer is only found in thick skin? What is thick skin?

Stratum lucidum- Thick skin is the skin only found on the palms and soles of feet.

What are Stretch Marks?

Stretch marks are extensive distortion of the dermis (exceeding limits of skin) and the resulting damage to the dermis prevents it from recoiling to original size and the skin wrinkles and creases creating stretch marks (thickened tissue resulting from extensive).

How is hair removed?

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What are the steps in deep wound healing? What happens in each stage?

- Bleeding occurs • Mast cells trigger inflammatory response • A scab stabilizes and protects the area • Germinative cells migrate around the wound • Macrophages clean the area • Fibroblasts and endothelial cells move in, producing granulation tissue • Fibroblasts produce scar tissue • Inflammation decreases, clot disintegrates • Fibroblasts strengthen scar tissue • A raised keloid may form

As skin ages, what changes occur?

- Epidermal thinning • Decreased numbers of dendritic (Langerhans) cells • Decreased vitamin D3 production • Decreased melanocyte activity • Decreased glandular activity (sweat and oil glands) • Reduced blood supply • Decreased function of hair follicles • Reduction of elastic fibers • Decreased hormone levels • Slower repair rate

ABCD rule of Melanoma

-A is for asymmetry because melanomas tend to be abnormal shape -B is for border because it is usually irregular shaped or notched -C is for color because it is generally mottles and combination of tan, brown, black, red, pink, white, and blue tones -D is for diameter because any skin growth larger than 5mm in diameter is dangerous

What are the 3 types of cells in the epidermis? What are their functions?

-Keratinocytes- most abundant cells in the epidermis and contains large amounts of keratin. They are water resistant but not water proof. Thin skin covers most of the body and contains 4 layers of keratinocytes. Thick skin covers the palms and soles of feet. Has a thicker stratum corneum and has 5 layers of keratinocytes including stratum lucidum which thin skin does not have.

What are the two layers of the dermis? What is found in each region?

-Papillary layer- consists of areolar tissue and contains capillaries, lymphatics, and sensory neurons. -Reticular layer- consists of an interwoven meshwork of dense irregular connective tissue that contains collagen and elastic fibers.

Know the skin color clues.

Carotene and Melanin

What provides extensibility and elasticity in the dermis?

Collagen

What are epidermal ridges? What causes them?

Epidermal ridges are formed by the stratum basale and extend into the dermis and are adjacent to dermal projections called dermal papillae. The strength of the attachment is proportional to the surface area of the basement membrane.

What are the two layers of the skin?

Epidermis and Dermis

Degrees of Burns

First degree and second degree are also called partial thickness burns because the damages is only restricted to the superficial layers of the skin. First Degree burns only affect the epidermis. Second Degree damages all the epidermis and some of the dermis. Third degree burns damage is that is destroys the epidermis and the dermis and extends into the hypodermis. These can be less painful than second degree burns because the sensory nerves are destroyed and these burns can require skin grafts because the epithelial cells are unable to cover themselves.

What are the 3 types of hair?

First is the Lanugo hairs which is "baby hair" and is extremely fine and unpigmented. Vellus hairs are the soft fine hairs that cover most of the body surface. Then we have the Terminal hairs which are heavy and more deeply pigmented and sometimes even curly. Also these hairs include our head hair, eyebrows and eyelashes.

Know that hair is affected by illness, radiation therapy, chemotherapy, and stress. Why does cancer treatment affect hair?

Hair loss in cancer treatment from chemotherapy occurs because chemo treatment is basically poison and it is attacking rapidly growing cancer cells and can sometimes also damage healthy cells such as hair follicles causing people to lose their hair. Also it can occur from radiation therapy in the area that has been treated because of the radiation.

What is cerumen?

It is Earwax. Forms from combination of secretions of ceruminous glands and sebaceous glands.

People have the same number of melanocytes. Why does skin look different?

Melanin, a naturally occurring sun-block that protects our skin cells from the harmful effects of ultra-violet radiation from the sun, is produced from the amino acid tyrosine by special cells called melanocytes. The production of melanin is controlled by an enzyme called tyrosinase and is stimulated by exposure to sunlight. People whose melanocytes do not produce very much tyrosinase will most likely have fair skin and will not tan easily. Some people inherit an inability to produce melanin because their melanocytes cannot make the enzyme tyrosinase and these people have a condition known as albinism.

What are cleavage lines? Why are these significant clinically?

Most of the collagen and elastic fibers at any location are arranged in parallel bundles oriented to resist the forces applied to the skin during normal movement and the resulting pattern of fiber bundles in the skin and establishes cleavage (tension) lines. They are clinically significant because a cute parallel to a cleavage line will usually remained closed and heal with little scarring where as cut at right angle to a cleavage lines will be pulled open as a severed elastic fibers recoil and will result in greater scarring. These reasons cause surgeons to choose to make incisions parallel to cleavage lines.

What is the function of melanin?

Protects our epidermis and dermis from harmful sun effects like UV radiation.

Where is tattoo dye in the skin and why?

Tattoo dye is dermis because if it was in the epidermis it wouldn't stay because the epidermis regenerates new skin every 30 days and would just go away. The tattoo dye has to be deep in the dermis in order to stay.

Contrast Epidermis and Dermis

The epidermis has 5 layers and has thick skin, thin skin, and keratinocytes. Also the epidermis has the color of the skin. The dermis is located in between the epidermis and the subcutaneous layer. The dermis has 2 components- papillary and reticular layers. (expand more)

What are the functions of hair?

The hair protects and insulates, guards openings against particles and insects (ear and nose), keeps sweat out of eyes, is sensitive to very light touch.

What is the hypodermis? What is its function?

The layer of loose connective tissue below the dermis (areolar connective and adipose tissue). It connects skin to underlying muscles. (stabilizes position of the skin)

Where are sebaceous glands, what is their function?

They are oil glands and they discharge an oily lipid secretion into hair follicles. They secrete sebum, which inhibits bacterial growth and lubricates the hair and skin. *not associated with hair follicles*

What are sudoriferous glands?

They are sweat glands and needed to keep the body cooled or used for cooling.

What are the functions of nails?

They protect the exposed dorsal surfaces of the tips of the fingers and toes. They also help limit distortions of the digits when they are exposed to mechanical stress (grasping objects).

Notice that collagen is found in the dermis. Where else have we seen collagen?

We have seen collagen in the elastic tissue which is located in the dense connective tissues.

What are the 5 layers of the epidermis? What are their components?

• Stratum basale/germinativum (single layer) • Is attached to basement membrane by hemidesmosomes • Forms a strong bond between epidermis and dermis • Forms epidermal ridges (e.g., fingerprints) to increase surface area for grasping fig 5-4 • Dermal papillae (tiny mounds) • Increase the area of basement membrane • Strengthen attachment between epidermis and dermis • Has many basal cells or germinative cells • Specialized Cells of Stratum Basale • Merkel cells • Found in hairless skin • Respond to touch (trigger nervous system) • Melanocytes • Contain the pigment melanin • Scattered throughout stratum basale • Stratum Spinosum — the "spiny layer" • Produced by division of stratum basale • Eight to ten layers of keratinocytes bound by desmosomes • After a sunburn, why does skin peel off in a layer? • Contain dendritic (Langerhans) cells, active in immune response • Stratum Granulosum — the "grainy layer" (3-5 layers) • Stops dividing, starts producing • Keratin • A tough, fibrous protein • Makes up hair and nails • Keratohyalin • Dense granules • Cross-link keratin fibers • Stratum Lucidum — the "clear layer" • Found only in thick skin • Filled with keratin • Covers stratum granulosum • Stratum Corneum — the "horn layer" • Exposed surface of skin • 15 to 30 layers of keratinized cells • Water resistant • Keratinization • The formation of a layer of dead, protective cells filled with keratin—water resistant but not waterproof • Occurs on all exposed skin surfaces except eyes • Skin life cycle • It takes 15-30 days for a cell to move from stratum basale to stratum corneum • New epidermis every 30 days