BIOL235_Chap5 Flashcards
Integumentary System
System composed of skin, hair, oil and sweat glands, nails and sensory receptors.
Skin
Cutaneous membrane
Cutaneous membrane
covers body’s external surface and is largest organ by weight
Epidermis
superficial, thinner and upper portion of skin
Avascular
no bleeding if broken
Dermis
Deeper/thicker connective tissue portion of skin
Vascular
bleeding if broken
Subcutaneous layer
hypodermis
Subcutaneous layer
not part of skin. fibers from the dermis anchor skin to this layer
areolar + adipose tissues
Lamellated corpuscles (pacinian corpuscles)
nurve endings where the large blood vessels that supply the skin are
sensitive to pressure
4 Epidermis cells
keratinocytes
melanocytes
intraepidermal macrophages
tactile epithelial cells
keratinocytes
90% of epidermal cells
produce protein keratin
produce lamellar granules
Melanocytes
8% of epidermal cells
produce melanin pigment
Melanin
yellow-red or brown-black pigment absorbs damaging UV light. protect from UV light on the skin
intraepidermal macrophages = langerhans cells
small fraction of epidermis cells
immune responses . help other cells of hte immune system recognize an invading microbe + desroy invading microbe
Tactile epithelial cells = Merkel cells
least numerous epidermal cells
deepest layer of epidermis
contact tactile disc/Merkel disc
thin skin
the 4 strata of epidermis that most regions of the body have
(Stratum basale, stratum spinosum, stratum granulosum, + thin stratum corneum)
thick skin
the 5 layers of the epidermis the body has at points of high friction (fingertips, palms, soles etc.)
(Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum + thick stratum corneum)
Stratum basale
deepest layer of epidermis
some are stem cells
Stratum spinosum
2nd deepest epidermis layer
keratinocytes produced from below in stratum basale layer
some can still divide.
Stratum granulosum
3rd deepest layer of epidermis (middle layer of epidermis)
3-5 layers of keratinocytes undergoing apoptosis (dying)
keratohyalin protein present
transition between deeper/metabolically active strata/layers and more superficial strata
lamellar granules
secretion deposited in between cell spaces of stratum granulosum, lucidum and corneum
water repellent sealant.
Stratum lucidum
layer/stratum of epidermis only presnt in thick skin areas - fingertips, palms, soles
dead keratinocytes with lots of keratin and thickened plasma membranes.
Stratum Corneum
Uppermost layer of epidermis
lots of dead keratinocytes. thin cells. final product of differentiation process.
Callus
constant exposure of skin to friction stimulates inc cell + keratin production and forms thickening of stratum corneum
Keratinization
the process by which cells move from one epidermal layer to the next accumulating increasing levels of keratin
Epidermal growth factor
hormonelike protein that plays a role in how cell division rates in the stratum basale inc when outer layers of the epidermis are stripped away like in abrasions and burns
dandruff
excessive amount of keratinized cells shed from skin of scalp
Dermis
deeper part of the skin
composed of dense irregular connective tissue contaning collagen + elastic fibers
great tensile strength + elasticity
dried + treated = leather
blood vessles, nerves, glands + hair follicles within
essential to epidermis survival
-thin superficial papillary region + thick deeper reticular region
Papillary region
very thin layer of dermis.
has dermal papillae
Dermal papillae
small, nipple-shaped structures that project into the undersurface of the epidermis.
contain capillary loops (blood vessels)
sometimes contain corpuscles of touch (Meissner corpuscles
some contain free nerve endings
Corpuscles of touch
(Meissner corpuscles)
nerve endings that are sensitive to touch
Free nerve endings
dendrites that lack any apparent structureal specialization
give rise to sensations of warmth, coolnes, pain, tickling + itching