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Test #2

When the arrector pili muscles contract

"Goose bumps" are formed

If the papilla of a hair follicle is destroyed,

the follicle will lose its blood supply

Earwax is produced by ________ glands.

ceruminous

Nail production occurs at the nail

nail root

What is the composition of the nail body?

dead, tightly compressed epidermal cells packed with keratin

As we age, muscle weakness occurs, due partially to which of the following?

decreased epidermal production of vitamin D3

Wrinkles in elderly individuals are the result of

loss of elastic filaments in the reticular layer of the dermis.

Vitamin D3 formed within the skin has all of these effects on other organ systems

is essential for absorption of calcium and phosphorus by the digestive system.
functions as a precursor for the hormone calcitriol in the endocrine system.
is essential for bone maintenance.is essential for bone growth

During wound repair, the activity of which cells leads to the appearance of collagen fibers and typical ground substance?

fibroblasts

Granulation tissue is composed of

clotted blood.
fibroblasts.
an extensive capillary network.

A fibrin clot that is formed over a skin wound is called a(n) ________.

scab

The large proximal projection on the femur is termed the

trochanter

The process of osteolysis is performed by which cell population?

osteoclasts

Which structural features of spongy bone are oriented along stress lines and are cross-braced extensively?

trabeculae

The central canal of an osteon contains

blood vessels

Terminal hairs

(large, coarse, darkly pigmented hairs such as on head or armpits)

Vellus hairs

(smaller, shorter, delicate on general body surface)

Hair follicle

Forms a single hair
Composed of epithelial and connective tissues

Layered structure of Hair (from innermost to outermost)

Internal root sheath (surrounds hair root; deeper only)
External root sheath (entire length of follicle)
Glassy membrane (thick, clear basal lamina)
Connective tissue sheath

Base of Hair contains...

hair bulb (epithelial cap) and hair papilla (peg of connective tissue with blood vessels and nerves)

Active phase of hair growth lasts?

2-5 years

What is a club hair

dead cell

Hair color is the result of...

variations in pigments produced in melanocytes at hair papilla

Sebaceous glands

oil glands, keep hair from becoming brittle, also antimicrobial (low ph)

Sebum is a mixture of...

triglycerides, cholesterol, proteins, and electrolytes

2 types of sweat Glands & Myoepithelial cells

apocrine sweat glands and merocrine sweat glands
myoepithelial cells squeeze gland to discharge secretion (function to wash epidermal surface)

Apocrine Sweat Glands

strongly influenced by hormones, include ceruminous glands and mammary glands, limited distribution (axillae, groin, nipples)

Merocrine sweat glands

found in most areas of skin, produce watery secretion with electrolytes, influenced by nervous system, important in thermoregulation and excretion.

Nails

composed of dead cells packed with keratin

Lunula

near the root the dermal blood vessels may be obscured, leaving pale crescent known as lunula

Age related skin changes

fewer melanocytes, thinning drier epidermis, diminished immune response (The number of dendritic cells
decreases to about half), Merocrine sweat glands
become less active, and with
impaired perspiration, REDUCED BLOOD SUPPLY, slower skin repair, fewer active follicles

Thyroid Hormones and skin function

maintain normal blood flow to papillary plexus

Sex Hormones

increase epidermal thickness, accelerate wound healing, increase number of dendritic cells protecting against cancer cells and pahogens

Epidermal growth factor

peptide that has widespread effects on epithelia, produced by salivary glands and glands in duodenum. Promote cell division in stratum basale and spnosum, accelerate production of keratin, stimulate epidermal development and repair.

Growth Hormone

stimulates fibroblast activity and collagen production, thickens epidermis, promotes wound repair

Vitamin D3

Sunlight and diet, UV radiation causes epidermal cells of stratum spinosum & basale to convert steroid to cholecalciferol

Step 1 Skin regeneration

mast cells in region trigger inflammatory response, bleeding occures

Step 2 (several hours)

blood clot or scab forms to restrict entry of microorganisms. Macrophages patrol damaged area & phagocytizing debris and pathogens, cells of stratum basale undergo rapid division

Step 3 (after one week)

blood clot begins to dissolve, fibroblasts create more collagen fibers and ground substance

Step 4 (several weeks)

scab sheds, epidermal repair completes, scar tissue created by fibroblasts raise up epithelium, replaces damaged accessory structures of skin

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