Block III skin video 3 Flashcards
What are the epidermally derived appendages?
- hairs
- sebaceous glands
- eccrine sweat glands
- appocrine sweat glands (also ceruminous glands of ear & glands of Moll of eyelashes)
- Nails
- mammary glands
(all rise embryonically from invaginations of epidermis into CT)
Are hairs keratinzed?
maximally
on what does hair growth depend?
on contact with hair dermal papilla at base
What muscle is related to hair?
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
identify
Micrograph showing the
base of a hair follicle with the hair
dermal papilla and (inset) the
region of growth and
melanization
identify
micrograph showing hair follicles
What is the strucutre of sebaceous glands?
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]
What does sebaceous glands secrete?
Secrete sebums - a fatty substance which serves
to lubricate skin and hairs
What type of secretion does sebaceous glands do?
Glands have a holocrine mode of secretion. The
whole cell is lost as part of the secretion
Identify
Micrographs at lower and higher
magnifications of sebaceous glands
identify
High magnification micrograph of sebaceous
gland secretory portion
What helps sebaceous glands push sebum into duct?
Contraction of arrector pili muscle (smooth
muscle)
identify
Micrograph with arrector pili muscle indicated by the arrow from
where are eccrine sweat glands found? and its function
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)
what does secretion of eccrine sweat gland have?
secretion hypotonic relative to blood. Contains
potassium, sodium, chloride, lactate, and urea.
- secretion initially is isotonic, but duct cells
reabsorb sodium and chloride ions
identify
Medium magnification micrograph of eccrine
sweat glands secretory portion and duct
identify
Secretory Portion of Eccrine Sweat Gland (myoepithelial cells- contractile)
-pseudostratified cuboidal
identify
Duct of Eccrine Sweat Gland
-stratified cuboidal
Where is apocrine sweat gland located?
Found in the axilla, around
nipple, external auditory
meatus, eyelids, and
anogenital regions.
how is the secretory portion of apocrine sg?
much larger in diameter than
for eccrine sweat gland.
Simple Columnar epithelium
when is this glad activated (apocrine)
Gland not functional until after puberty
what does apocrine SG secrete?
Secretion rich in protein,
carbohydrate, ammonia, and
lipids
function of apocrine SG?
Function not clear.
Secretion may have
pheromone properties
IDENTIFY
Higher magnification image of secretory portion of gland
showing the simple cuboidal epithelium
identify
Low magnification micrograph of skin showing apocrine sweat
glands in the hypodermis
Which are the neural receptors of the skin?
- 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
identify
Pacinian corpuscle
identify
Meissners corpuscle
identify
Meissners corpuscle
identify
Pacinian corpuscle
What are the major plexuses of vasculature of skin?
- deep plexus - large vessels in epidermis
- cutaneous plexus - between epidermis and dermis (gives rise to capillaries)
- papillary plexus - border of reticular layer of dermis
what are atrovenus shunts?
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.
