Block III skin video 3

Question 1

What are the epidermally derived appendages?

Answer 1

1. hairs
2. sebaceous glands
3. eccrine sweat glands
4. appocrine sweat glands (also ceruminous glands of ear & glands of Moll of eyelashes)
5. Nails
6. mammary glands
   (all rise embryonically from invaginations of epidermis into CT)

Question 2

Are hairs keratinzed?

Answer 2

maximally

Question 3

on what does hair growth depend?

Answer 3

on contact with hair dermal papilla at base

Question 4

What muscle is related to hair?

Answer 4

Arrector Pili muscle is often associated with the
hair. Is smooth muscle which typically attaches to hair follicle at one end and to the papillary layer of dermis at the other end and raises the hair when cold or frightened. Is responsible for goose
bumps

Question 5

identify

Answer 5

Micrograph showing the
base of a hair follicle with the hair
dermal papilla and (inset) the
region of growth and
melanization

Question 6

identify

Answer 6

micrograph showing hair follicles

Question 7

What is the strucutre of sebaceous glands?

Answer 7

Simple acinar gland - typically with a short duct
that empties into a hair follicle (although ducts
in some areas open on surface of skin) [well developed SER]

Question 8

What does sebaceous glands secrete?

Answer 8

Secrete sebums - a fatty substance which serves
to lubricate skin and hairs

Question 9

What type of secretion does sebaceous glands do?

Answer 9

Glands have a holocrine mode of secretion. The
whole cell is lost as part of the secretion

Question 10

Identify

Answer 10

Micrographs at lower and higher
magnifications of sebaceous glands

Question 11

identify

Answer 11

High magnification micrograph of sebaceous
gland secretory portion

Question 12

What helps sebaceous glands push sebum into duct?

Answer 12

Contraction of arrector pili muscle (smooth
muscle)

Question 13

identify

Answer 13

Micrograph with arrector pili muscle indicated by the arrow from

Question 14

where are eccrine sweat glands found? and its function

Answer 14

Found over surface of most of body except glans
penis, clitorus, and labia minora

In most areas involved in thermoregulation (cholinergic innervation)

greatest numbers on palms and soles of feet
(secretion here neurally stimulated by fear or
stress – adrenergic innervation)

Question 15

what does secretion of eccrine sweat gland have?

Answer 15

secretion hypotonic relative to blood. Contains
potassium, sodium, chloride, lactate, and urea.

• secretion initially is isotonic, but duct cells
  reabsorb sodium and chloride ions

Question 16

identify

Answer 16

Medium magnification micrograph of eccrine
sweat glands secretory portion and duct

Question 17

identify

Answer 17

Secretory Portion of Eccrine Sweat Gland (myoepithelial cells- contractile)

-pseudostratified cuboidal

Question 18

identify

Answer 18

Duct of Eccrine Sweat Gland

-stratified cuboidal

Question 19

Where is apocrine sweat gland located?

Answer 19

Found in the axilla, around
nipple, external auditory
meatus, eyelids, and
anogenital regions.

Question 20

how is the secretory portion of apocrine sg?

Answer 20

much larger in diameter than
for eccrine sweat gland.
Simple Columnar epithelium

Question 21

when is this glad activated (apocrine)

Answer 21

Gland not functional until after puberty

Question 22

what does apocrine SG secrete?

Answer 22

Secretion rich in protein,
carbohydrate, ammonia, and
lipids

Question 23

function of apocrine SG?

Answer 23

Function not clear.
Secretion may have
pheromone properties

Question 24

IDENTIFY

Answer 24

Higher magnification image of secretory portion of gland
showing the simple cuboidal epithelium

Question 25

identify

Answer 25

Low magnification micrograph of skin showing apocrine sweat
glands in the hypodermis

Question 26

Which are the neural receptors of the skin?

Answer 26

• Free nerve endings - pain and temperature
• Merkel Cells - 2 point discrimination - light
  pressure
• Pacinian Corpuscle - heavy pressure
• Meissner’s corpuscle - light pressure
• Ruffini’s corpuscle - responds to movement
  of adjacent collagen fibers & mechanical stress
• Krause’s corpuscle – responds to cold
  temperatures

Question 27

identify

Answer 27

Pacinian corpuscle

Question 28

identify

Answer 28

Meissners corpuscle

Question 29

identify

Answer 29

Meissners corpuscle

Question 30

identify

Answer 30

Pacinian corpuscle

Question 31

What are the major plexuses of vasculature of skin?

Answer 31

1. deep plexus - large vessels in epidermis
2. cutaneous plexus - between epidermis and dermis (gives rise to capillaries)
3. papillary plexus - border of reticular layer of dermis

Question 32

what are atrovenus shunts?

Answer 32

A key feature is that there are extensive arteriovenus shunts present between the arteries and veins.

In extreme cold, these shunts open, thus shunting blood away from the skin capillaries, thus conserving
body heat at expense of frostbite of skin.