6 - Skin Glands Flashcards
Excrete their products into the hair follicle
Sebaceous glands
Apocrine sweat glands
Excrete directly into the skin surface
Eccrine glands
Holocrine secretion
Sebaceous glands
Merocrine secretion
Apocrine and eccrine sweat glands
Totally devoid of sebaceous glands
Palms and soles
Largest and greater density of sebaceous glands
Nose
Face
Scalp
Sebaceous glands arise in a _____ sequence
Cephalocaudal
Earliest known signal necessary for sebaceous gland development
SOX9
Subpopulation of stem cells expressing _____ is established near the entrance of the sebaceous gland; marker of terminal epithelial cell differentiation
PRDM1 (formerly known as BLIMP-1)
Advanced differentiated vs undifferentiated sebocytes
Advanced differentiated:
increased size
Decreased nucleocytoplasmic ratio
Sebocyte stem cell signaling pathway
Increased Shh
Increased Myc
Decreased Wnt
Hair cell stem cell signaling pathway
Increased Wnt
Decreased Lef1
Basal cells of the peripheral zone from about _____% of the sebaceous gland
40
Maturation zone represents about _____% of the sebaceous gland
40
Distinguish sebum from lipids of human internal organs
Wax esters
Squalene
Form 40-60% of total skin surface lipids
Triglycerides
Diglycerides
Free fatty acids
“Normal” mammalian pathway of desaturation
Inserting a double bond between the 9th and 10th carbons of stearic acid to from oleic acid
Sebaceous gland pathway of desaturation
Insertion of a delta 6 double bond into palmitic acid resulting to sapienic acid
Major fatty acid of adult human sebum
Sapienic acid
Elongation of sapienic acid by two carbons and insertion of another double bond gives
Sebaleic acid
Fatty acid thought to be unique to human sebum
Sebaleic acid
Function of sebum
Maintaining stratum corneum hydration
Mild antibacterial action
Transit mechanism for vitamin E
Mild antibacterial action of sebum due to
Antiinflammatory lipids and immunoglobulin A
Cathelicidin in sebum has direct antimicrobial activity against
Propionibacterium acnes
Free fatty acids in sebum are bactericidal against
Gram-positive organisms
Skin stem cells can be found in
Follicle bulge
Base of sebaceous gland
Basal layer of epidermis
Average transit time of sebaceous gland cells from formation to discharge
7.4 days
Size of sebaceous glands (increases/decreases) with age
Increases
Number of sebaceous glands (increases/decreases) with age
Remains the same
Turnover of the sebaceous glands in older adults is (faster/slower) compared with young adults
Slower
Y/N: Levels of testosterone parallel the patterns of sebaceous gland activity
No - do not parallel
Most powerful androgens
Testosterone
5-DHT
Probably a significant regulator of sebaceous gland activity through its conversion to testosterone and DHT
Dehydroepiandrosterone sulfate (DHEAS)
Levels of DHEAS (high/low)
- Newborns
- 2-4 year old children
- Newborns - high
2. 2-4 year old children - very low
Decline in DHEAS starts in
Early adulthood
Most potent pharmacologic inhibitor of sebum secretion
Isotretinoin