Ch 4 Flashcards
Integumentary System
Cutaneous membrane: epidermis and dermis
Accessory structures: hair, nails, glands
Functions of integumentary system
protects: mechanical, chemical, bacterial, and thermal damage, UV radiation, and desication, aids in heat regulation, excretion of urea and uric acid, synthesis of vitamin D
Epidermis characteristics
stratified squamous epithelium
lacks blood vessels but can divide
as new ones grow, push old to surface
Epidermal cell types
keratinocytes, melanocytes, lagerhan cells, merkel cells
Keratinocytes
produce keratin, provide protection
Melanocytes
produces melanin
Lagerhan cells
from bone marrow, part of immune response
Merkel cells
in deepest layer, form touch receptors with sensory neurons
Keratinization and Epidermal Growth
stem cells divide to produce keratinocytes at the basal lamina
as keratinocytes are pushed up towards the surface they fill with keratin and oils and slowly die
4 week journey
Layers of epidermis
stratum germinativum, stratum spinosum, stratum granulosum, stratum corneum
Stratum germinativum
deepest single layer of cells
combination of merkel cells, melanocytes, keratinocytes, and stem cells that divide repeatedly
attached to each other and to basal lamina
Stratum Spinosum
8 to 10 cell layers held together by desmosomes
melanin taken in by phagocytes from nearby melanocytes
Stratum granulosum
3-5 layers of flat dying cells
show nuclear degeneration
contain dark staining keratohylin granules
Stratum lucidum
seen in thick skin on palms and soles of feet only
three to five layers of clear, flat, dead cells
Stratum corneum
25 to 30 layers of flat dead sells filled with keratin and surrounded by lipids
continuously shed
barrier to light, heat, water, chemicals, and basteria
friction stimulates callus formation
Thick skin
palmer and platar surface
about 30 layers of s. corneum
all 5 layers
Thin skin
rest of body surface
fewer layers of s. corneum
no s. lucidum
Epidermal ridges (finger tips)
stratum germinativum forms ridges that extend into the dermis
increases area of contact for better grip
Melanin
melanin produced in epidermis by melanocytes
similar number of melanocytes in everyone
different amounts of pigment produced
UV light
increases melanin production, which it absorbs
too much UV can damage chromosomes
Types of melanin
melanocytes convert tyrosine to melanin
brown or black is called eumelanin
red brown is called pheomelanin
Carotene in dermis
yellow orange pigment
found in stratum corneum and subcutaneous
Hemoglobin
red oxygen carrying pigment in blood cells
if other pigments are not present, epidermis is transulcent so pinkness will be evident
Dermis
Papillary layer and reticular layer
Papillary layer
areaolar CT
capillaries and neurons
dermal papillae
Reticular layer
anchoring layer
large vessels, nerves, adipocytes, arrector pili muscle
dense irregular CT- collagen and elastic