40 terms

A&P Hair/Skin

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.
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?
Granulation tissue is composed of
clotted blood.
an extensive capillary network.
A fibrin clot that is formed over a skin wound is called a(n) ________.
The large proximal projection on the femur is termed the
The process of osteolysis is performed by which cell population?
Which structural features of spongy bone are oriented along stress lines and are cross-braced extensively?
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.
composed of dead cells packed with keratin
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