Structure/function of eccrine, apocrine and sebaceous glands

Question 1

What areas are sebaceous glands not associated with the pilosebaceous unit?

Answer 1

Vermilion border, prepuce, nipple/areola, tarsal plate, and superficial eyelid margin

Question 2

What is the primary composition of sebum?

Answer 2

Triglycerides>wax esters>squalene>cholesterol and its esters

Question 3

What is different in acne patient’s sebaceous glands?

Answer 3

larger, produce more sebum but the composition is largely unchanged

Question 4

Which is the most potent androgen for affecting sebaceous glands?

Answer 4

DHT –> increase proliferatio/differentiation and lipid synthesis. May Increased infundibular keratinization too

Question 5

Where is eccrine gland concentration the highest?

Answer 5

palms and soles

Question 6

Where are eccrine glands not found?

Answer 6

Clitoris, glans penis, labia minora, external auditory canal, lips

Question 7

What neurotransmitter do eccrine glands respond to? And what autonomic system does this function line up with?

Answer 7

Eccrine glands respond to Ach not NE, but they function with the sympathetic nervous system (you get sweaty when you are nervous.)

Question 8

What type of secretion do eccrine glands utilize?

Answer 8

merocrine (exocrine glands –>secretions are secreted via exocytosis onto an epithelial-walled duct

Question 9

What type of cells make up the secretory coils on an eccrine gland and what do the cell types secrete?

Answer 9

Dark cells: sialomucin Clear cells: aqueous material + glycogen

Question 10

What body locations are apocrine glands found in?

Answer 10

axillae, anogenital, periumbilical, nipples, and areolae - present at birth and enlarges as puberty approaches

Question 11

What branch of the autonomic nervous system acts on the apocrine sweat glands and how do they secrete their contents?

Answer 11

Sympathetic nervous system and secretion via decapitation (portions of the cell enter into the lumen)

Question 12

Where are sebaceous not located?

Answer 12

palms and soles

Question 13

What areas have the most sebaceous glands?

Answer 13

face/scalp>trunk>extremities

Question 14

Where are apocrine glands not associated with the follicular unit and what is the name for the glands in the eyelid margins and external auditory canal?

Answer 14

vermillion border, prepuce, nipple/areola, tarsal plate and superficial eyelid margin (molls glands), external auditory canal (ceruminous glands)

Question 15

What is the composition of lipids coming from sebaceous glands?

Answer 15

Mainly triglycerides (~60%)>wax esters>squalene>cholesterol and its esters

Question 16

What fatty acid is essential for the sebocytes?

Answer 16

Linoleic acid –> Not produced by sebocytes

Question 17

What does linoleic acid deficiency cause?

Answer 17

Hyperkeratinization and retention of corneocytes in follicular infundibulum.

Question 18

Action on what sebocyte receptors causes sebocyte proliferation and increases lipid and androgen synthesis?

Answer 18

Growth hormone and insulin-like growth factor-1 receptors

Question 19

Activity of testosterone and dihydrotestosterone (DHT) on sebaceous gland?

Answer 19

Increase sebocytes proliferation and differentation and lipid synthesis (especially DHT) may increase infundibular keratinization

Question 20

What toll-like receptor is important in acne pathophysiology?

Answer 20

TLR-2 –> increased production of antimicrobial peptides and inflammatory cytokines/chemokines espeically IL-1beta and IL-17 via stimulation of TLR2 and the NLRP3 inflammasome increased free fatty acids (e.g. via lipase activity) may increase infundibular keratinization.