lesson 10 gritti Flashcards
substance made by sebaceous glands
sebum
where is the sebum released?
inside the hair follicle thanks to the degeneration of the rounded cells of the duct filled by lipid containing vacuoles
what’s the type of secretion of sebaceous glands
holocrine secretion
arrector pili muscle
attached on one side into the hair follicle and on the other side into the dermal papillae
where are sebaceous glands positioned?
into the dermis, near to the hair follicle
pilosebaceous unit
hair follicle, arector pili muscle and sebaceous gland
eccrine secretion
by eccrine sweat glands
no loss of cellular material
the sweat is released in the superficial surface of the skin
eccrine sweat glands
-coiled exocrine glands in the dermis/superficial hypodermis
-release their content into the surface of the skin via coiled secretory ducts
-sweat pores are exit points for sweat
-begin to function soon after birth
-ducts lined by simple or stratified cuboidal epithelium
apocrine sweat glands
-ducts lined by simple cuboidal epithelium
-bigger nuclei than eccrine sweat glands
-not functional until after puberty
-the duct open in the superficial part of the hair follicle
in both apocrine and eccrine sweat glands, which types of cells contract to move the secretion into the duct?
myoepithelial cells in the basal lamina
where can you find stem cells in the hair follicle?
in the bulge (at the level of entry/exit of the sebaceous glands) or in the papillary dermis
stem cells in the bulge are more heterogeneous in terms of stem cells differentiation (they give rise to multiple types of cells) while the stem cells in the papillary dermis are more homogenous: they give rise to the cells of the hair follicle.
stem cell niches characteristics
-anatomically defined
-not isolated: in contact with tissues and cells
-cell hierarchy inside the niche
-different types of stem cells in a single niche that can be identified by the expression of specific markers.
(usually they express the same makers but at different levels and that’s what distinguish them)
interfollicular epidermis
occupies the space between hair follicles in the skin
non hair baring part of the epidermis
asymmetric division can be
vertical or lateral
corneocytes
cells of the stratum corneum
15-30 layers
dead and flattened cells
no nuclei
cornification
process in which the corneocytes loose their nuclei and organelles becoming tough and protective cells filled with keratin
shape of cells of the stratum spinosum
polyglonal cells
type of cells of the stratum granulosum
flatten
papillary dermis type of connective tissue
loose conn tissue
more cells than fibers
reticular dermis type of connective tissue
dense connective tissue, more fibers than cells
name of the lines that divide the hypodermis in lobes
septa
infundibulum
from the opening of the hair follicle to the sebaceous gland
how is the epithelium at the bulb of the hair follicle?
cuboidal pseudostratified epithelium
isthmus
-in the middle part of the hair follicle
-from the duct of the sebaceous gland till the arector pili muscle attachment site
arector pili muscle, which type of muscles and how are the nuclei shaped?
the muscle is smooth
no striation
elongated nuclei
the skin is made of
dermis and epidermis.
hypodermis is subcutaneous tissue
where can we find sweat glands?
at the border between the reticular dermis and the hypodermis
ducts of sweat glands
-are more darkly stained
-stratified cuboidal epithelium (usually bilayered)
-coiled
-help to transport the sweat from the secretory portion to the skin surface
particular cells around the secretory portion of sweat glands
say name and shape
mioepithelial cells
flatten cells
they contract and help the sweat glands to transport the sweat
