5-8

Sebaceous Glands

• ___________ glands• ________________________ glands that discharge an oily lipid

secretion into hair follicles• Simple branched alveolar glands- communicate with a single follicle

and share a duct• Produce large quantities of lipids as they mature• Released through holocrine secretion- rupture of secretory cells

Lipids

• Enter the _________________ of the glands• ____________________________ muscles squeeze the sebaceous

gland and force the lipids into the hair follicle and surface of skin• _______________- secreted lipid; mix of triglycerides, cholesterol,

proteins and electrolytes• Inhibits growth of bacteria, lubricates and protects keratin of hair shaft, and

conditions surrounding skin

Sebaceous Follicles

• Glands not associated with hair follicles• ________________ discharge _______________ directly onto

epidermis• Located on face, back, chest, nipples and external genitalia

Sweat Glands

Apocrine Sweat Glands

• Armpits, around nipples, and in pubic region• Secrete products into _____________________________• Coiled, tubular• Produce a sticky, cloudy, and potentially odorous secretion• Rely on _______________________ secretion• Begin secreting at puberty• Sweat produced is a nutrient source for bacteria• Myoepithelial cells surround the secretory cells and contract and squeeze the

gland• Controlled by _____________________ system and circulating hormones

Merocrine (eccrine) Sweat Glands

• Coiled, tubular• Discharge secretions directly onto surface of skin• Adults have 2-5 million – __________________ and ____________

have the most• ____________________ perspiration• 99% H2O

Functions of Merocrine Glands

• Cooling surface of skin to reduce body temp- ___________________ perspiration• Excreting water and _________________________• Providing protection from environmental hazards by discouraging MO

growth• Flushing them from surface or making difficult for them to adhere• _____________________- peptide with antibiotic properties

Other Glands

• _______________________- interaction b/t sex hormones and pituitary hormones control secretion• ______________________- passageway of external ear• Secretions combine with nearby secretion glands to form cerumen

Control of Gland Secretions

• ANS controls sebaceous and ____________________ sweat glands• Commands affect all glands of that type• ________________________ glands are more precisely controlled

5-9

Nails

• Protect exposed ________________ surfaces of tips of fingers and toes• Help limit distortion of digits when subjected to mechanical stress

Parts of Nails

• _____________________- visible portion; covers nail bed• Dead, tightly compressed cells packed with keratin

• Nail bed- recessed deep to level of surrounding epithelium• Bound on either side by lateral nail grooves and nail folds• _____________________- distal portion that continues past nail bed• _____________________________- area of thickened stratum

corneum free edge extends over

Parts of Nail

• Nail root- where nail production occurs• Deepest portion lies close to bone

• __________________________- cuticle; portion of stratum corneum of nail root that extends over exposed nail• ____________________- pale crescent; caused by vessels being

obscured

5-10Regeneration of Skin

Step 1

• Damage extends through ________________ and into ______________ • Bleeding occurs

Step 2

• Blood clots or scab forms at surface and restricts entry of MOs• Bulk of clot consists of ________________- protein that forms from blood

proteins• Clot’s color reflects presence of trapped ________________• Cells of stratum germinativum undergo rapid divisions and migrate along

edges of wound• ________________________ remove debris and pathogens

Step 3

• ______________________________-blood clot, fibroblasts, and extensive capillary network• Over time, deeper portions of clot dissolves• ________________________ activity leads to appearance of collagen fibers

and ground substance

Step 4

• __________________ contains abnormally large # of collagen fibers and few blood vessels• Hair follicles, glands, and nerves are replaced by ________________

tissue• Formation of scar tissue completes repair process

Keloid

• _______________ tissue formation that continues beyond requirements of tissue repair• Thick, raised area of scar tissue• Covered by shiny, smooth epidermal surface• Upper back, _____________________, anterior chest, and earlobes

5-11

Aging

• ______________________ thins; connection b/t epidermis and dermis weakens• # of Langerhans cells decreases- reduces sensitivity of immune system• Vitamin D3 production declines by 75%-reduced calcium and

phosphate absorption• _______________________ activity declines

Aging cont

• _______________________ activity declines- skin dry and scaly• Blood supply to dermis reduced- skin cool• Hair follicles stop functioning or produce thinner, finer hairs• Dermis thins and elastic fiber network decreases in size• Secondary sexual characteristics in hair and body-fat distribution fade• Skin repairs ______________