Anatomy Lecture Ch 5 Review Questions Flashcards
What are the functions of the integumentary system?
regulate body temperature, store blood, protect body from external environment, detect cutaneous sensations, excrete and absorb substances, synthesize vitamin D
What type of tissue is the epidermis?
keratinized stratified squamous epithelium
what percent of epidermal cells are keratinocytes?
90%
What do keratinocytes produce?
keratin- a protein
What do keratinocytes do?
protect the skin and underlying tissues from heat, microbes, and chemicals
What do lamellar granules do?
release a waterproofing agent
What do melanocytes produce?
melanin, everyone has the same number of melanocytes but they make different levels of melanin
What are the functions of melanocytes besides producing melanin?
long thin projections transfer melanin granules to the keratinocytes
What are the functions of melanin?
skin color, absorbing damaging UV light
Who discovered intraepidermal/intraepithelial macrophages?
Langerhans
Where are intraepidermal macrophages derived?
red bone marrow
What is the function of intraepidermal macrophages?
microbial immune response
Where are tactile epithelial cells located?
in the deepest layers of the epidermis
What are the functions of tactile epithelial cells?
sensation and touch through tactile/contact discs
What are the layers of the epidermis from superficial to deep?
Stratum corneum. stratum lucidum, stratum granulosum, stratum spinosum, stratum basale
What does the stratum basale do?
contains the stem cells, germinating layer
What happens if the stratum basale is destroyed?
a skin graft is required
What are the three types of skin grafts?
Autograft, isograft, allograft
Where is healthy skin taken from in an autograft?
A healthy portion of the injured individual
Where is healthy skin taken from in an isograft?
an identical twin
Where is healthy skin taken from in an allograft?
A genetically non-identical individual, this is rare
What is the stratum spinosum comprised of?
intermediate filament bundles that insert into desmosomes, some melanocytes, some Langerhans cells
What does the stratum spinosum do?
provide strength and flexibilty
What is the stratum granulosum made of?
transition between deep, living cells and dead cells. dark staining granules of keratohyalin, lamellar granules
What does keratohyalin do?
bundles intermediate filaments into stronger bundles
What do lamellar granules do?
lipid/fat secretion, retards water loss from cells, blocks foreign materials using oils
Where is the stratum lucidum present?
only in thick skin areas- fingertips, palms of hands, soles of feet
What is the stratum lucidum made of?
densely packed layers of dead keratinocytes
Does the stratum corneum contain lamellar granules?
yes
What causes callusing?
Constant friction to the stratum corneum resulting in an abnormal thickening of the epidermis
What happens during keratinization and growth of the epidermis?
cells move toward superficial, cell contents replaced with keratin, governed by growth factors
What are the two layers of the dermis?
papillary and reticular
What is contained in the papillary dermis?
dermal papilla; corpuscles of touch; nerve endings for heat, cold, pain, tickle, and pinch
what is contained in the reticular dermis?
hair follicles, sebaceous glands, and sudoriferous glands
what is the reticular dermis composed of?
dense irregular connective tissue containing collage and elastin which provides strength and elasticity
what are epidermal ridges?
fingerprints and footprints, ridges that reflect contours of the underlying dermis
what is the purpose of epidermal ridges?
increased friction for better grasping
What 3 pigments affect skin color?
melanin, carotene, hemoglobin
what does melanin do in relation to skin color?
brown pigment made by melanocytes, organelle melanosomes produces melanin in response to UV light
what is carotene?
yellow orange pigment that resides in the stratum basale
what does hemoglobin do in relation to skin color?
pink pigment going through blood vessels in the dermis
what enzyme is lacked in albinism patients?
tyrosinase
what does tyrosinase do?
necessary to convert tyrosine to melanin, tyrosine is the basis for melanin
what causes vitiligo?
complete or partial loss of melanocytes from patches of skin
what is cyanosis?
blue skin due to oxygen depravation
what is jaundice?
yellow skin due to high bilirubin, liver disease, low liver function
what is erythema?
redness due to injury/irritation
what is pallor?
paleness of skin, best assessed in nailbeds or gums
what causes acne?
inflammation of sebaceous (oil) glands due to increased sebum production and infection
where are sebaceous glands located?
lips, glans penis, labia minora, tarsal glands, small in trunk and limbs, absent in palms and soles
what layer of the skin are sebaceous glands located in?
dermis, mostly connected to hair follicles
what is sebum made of?
mixture of triglycerides, cholesterol, proteins, and inorganic salts
what is the function of sebum?
prevents hair from drying out, prevents water loss from skin, keeps skin soft, inhibits growth of some bacteria
when are sebaceous glands active?
mostly starting during puberty
where are eccrine sweat glands located?
throughout the skin of most regions of the body, especially the forehead, palms, and soles
what layer of the skin are eccrine glands located?
mostly in deep dermis, sometimes in upper subcutaneous layers, surface of epidermis
what type of sweat do eccrine glands produce?
perspiration consisting of water, ions, urea, uric acid, ammonia, amino acids, glucose, and lactic acid
what do eccrine sweat glands do?
regulate body temperature, waste removal, stimulated during emotional stress
when are eccrine sweat glands activated?
soon after birth
where are apocrine sweat glands located?
skin of axillae (armpits), groin, areolae, bearded regions of race, clitoris, and labia minora
what layer of the skin are apocrine sweat glands located in?
mostly in deep dermis and upper subcutaneous layers, around hair follicles
what type of sweat do apocrine sweat glands produce?
the same type as eccrine sweat glands with the addition of lipids and proteins
when are apocrine sweat glands stimulated?
during emotional stress and sexual excitement
when are apocrine sweat glands first activated?
puberty
what are the principle purposes of sweat?
regulation of body temperature and waste removal
where are ceruminous glands located?
external auditory canal
what layer of skin are ceruminous glands located in?
subcutaneous layers
what do ceruminous glands produce?
cerumen/ear wax
what is the purpose of cerumen?
impede entrance of foreign bodies and insects into external ear canal, waterproof canal, prevent microbes from entering cells
when are ceruminous glands activated?
soon after birth
how does the skin thermoregulate?
sweat and blood flow changes
What does constriction of blood vessels do in thermoregulation?
response to cold
what does dilation of blood vessels do in thermoregulation?
response to overheating
what percent of the total blood is located in the dermal region of the skin?
8-10%, can be redirected to general circulation when needed
what does the skin protect from?
UV light, bacteria, physical abrasion, dehydration
what does absorption of lipid soluble materials through the skin allow for?
steroids to work on allergic reactions, transdermal drug administration
how does the skin synthesize vitamin D?
precursor molecules of vitamin D are activated by UV rays to become the active form of vitamin D
how are epidermal wounds healed?
enlargement and migration of basal cells and division of migrating and stationary basal cells, under direction of epidermal growth factor
when is deep wound healing necessary?
when an injury extends to tissues deep to the epidermis
what is fibrosis?
scar formation
what are the phases of deep wound healing?
inflammatory, migratory, proliferative, maturation
what occurs during the inflammatory phase of deep wound healing?
epithelial cells migrate across the wound, a blood clot unites the wound edges, phagocytes and fibroblasts enter the wound site
what occurs during the migratory phase of deep wound healing?
epithelial cells beneath the scab bridge the wound, fibroblasts begin scar tissue, damaged blood vessels begin to grow
what happens during the proliferative phase?
the events of the migratory phase intensify
what happens during the maturation phase?
scab sloughs off, collagen fibers become more organized, fibroblasts decrease in number, blood vessels return to normal
Which layer of the skin is known as the subcutaneous layer?
hypodermis
Which layer of the skin are the pigment-producing cells located in?
stratum basale
What type of tissues make up the hypodermis?
areolar and adipose
What do lamellar corpuscles sense?
pressure
What are the 4 main cell types of the epidermis?
keratinocytes, melanocytes, dendritic, tactile epithelial
What is the stratum basale composed of?
a single row of cuboidal or columnar keratinocytes
What is the stratum spinosum composed of?
numerous keratinocytes arranged in 8-10 layers
What does the stratum granulosum consist of?
3-5 layers of flattened keratinocytes that are undergoing apoptosis (cell death)
What is the stratum lucidum composed of?
4-6 layers of flattened, clear, dead keratinocytes that contain large amounts of keratin and thickened plasma membranes
What does the stratum corneum consist of?
on average 25-30 layers of flattened dead keratinocytes, but can range in thickness from a few cells in thin skin to 50 or more cell layers in thick skin
What are the 3 layers of hair?
medulla, cortex, and cuticle
Where is the pigment of hair contained?
medulla
What part of the hair is responsible for cell division?
hair matrix
What is the arrector pili muscle?
a smooth muscle that extends from the papillary dermis of the skin to the dermal root sheath around the base of the hair follicle
What does the arrector pili muscle do?
pulls the hair shafts perpendicular to the skin surface causing goosebumps
What are hair root plexuses?
dendrites of neurons that generate nerve impulses if the hair shaft is moved, touch sensitive
What are the stages of the hair growth cycle?
growth, regression, resting
What happens during the growth stage of hair growth?
cells of the hair matrix divide and the new cells are added to the base of the hair root, pushing the existing cells upward which eventually keratinize and die
What happens during the regression stage of hair growth?
movement of the hair away from the blood supply in the papilla of the hair which results in the cells of the hair matrix to stop dividing, the hair follicle atrophies/shrinks, and the hair stops growing
What happens in the resting stage of hair growth?
the old hair root falls out or is pushed out of the hair follicle, after this a new growth stage begins
What is lanugo?
very fine, nonpigmented, downy hairs that cover the body of the fetus
What are terminal hairs?
hairs that replace the lanugo of the eyebrows, eyelashes, and scalp prior to birth; long, coarse, heavily pigmented
What are vellus hairs?
peach fuzz, cover most of the body where there is not terminal hairs
