Lecture 4 Flashcards
what are keratins?
translucid scleroproteins formed by 6-8 polypeptides
how do melanocytes make melanin?
via melanosomes:
- tyrosine turns into 3,4 dihydroxy phenylalanine by tyrosinase
- then it is turned into dopaquinone by tyrosinase
- then it turns into melanin
what are the different types of melanin?
eumelanin (brown) and pheomelanin (red)
what are melanocytes and where are they found?
ovoid-shaped cells (found in the stratum germinativum) with projections intertwined in the stratum spinosum
how does melanin go to epithelial cells?
melanosomes are phagocytosed (part of the projections) into the cells of the spinosum and it sits on the edge of the nucleus, which protects it (the DNA) from UV rays
describe the cells of the sebaceous gland?
non-squamous stratified epithelium
what is contained in sebacous cells?
lipid droplets with cholesterol, phospholipids, triglycerides, and glycogen
what stimulates and inhibits sebum release from sebaceous glands?
stimulated by androgens and inhibited by estrogens
what is contained in sweat?
water, urea, ammonia, NaCl
role of sweat glands
thermoregulation by evaporation cooling
type of secretion of sebaceous glands
holocrine secretion
type of secretion of sweat glands
merocrine secretion
types of secretion
merocrine, apocrine, and holocrine
merocrine secretion
secretory vesicles released only
apocrine secretion
part of the cell pinched off
holocrine secretion
mature cell dies and becomes secretory product
shape of the sweat gland
simple coiled tubular
what type of fluid is released from sweat glands?
serous (watery, protein-rich fluid)
what are the different parts of the sweat gland and where is each found?
secretory portion: hypodermis
duct (excretory portion): dermis and hypodermis
Difference Between Secretory Portion and Ductal Portion of Sweat Gland
ductal:
- cell size is small
- 2 cell layers ( stratified cuboidal epithelium)
- darkly stained (basophilic)
- small in diameter
- not surrounded by myoepithelial cells
secretory portion:
- cell size is larger
- one cell layer (simple columnar)
- lightly stained
- large in diameter
- surrounded by myoepithelial cells
where are trichohyalin granules found?
Huxley’s layer in the internal root sheath
cells found in the sebaceous gland?
basal cell layer (stem cells) that go up and turn into sebaceous cells that slowly fill with lipid (sebum)
describe the cells of the external root sheath.
cuboidal keratinized cells
describe the cells of the internal root sheath.
- Henle’s layer : squamous
- Huxley’s layer: cuboidal – has trichohyalin granules (acidophilic)
- Cuticle of IRS: squamous cells (partially keratinized)
