what are some functions of the integument?
- protection (physical, chemical, pathogens, UV)
- thermoregulation
- pressure/touch reception
- excretion (glands)
- production of vitamin D
what are the 5 layers of the epidermis?
1) stratum corneum
2) stratum lucidum
3) stratum granulosum
4) stratum spinosum
5) stratum basale
which layer of the epidermis has basophilic keratohyalin granules?
stratum granulosum
what gives spinous cells of stratum spinosum their spiny appearance?
desmosomes
in which layer does cell death begin to occur?
stratum granulosum = nuclear fragmentation (some cells have condensed nucleus and some have no nucleus at all)
*fully differentiated keratinocyte is dead
what structures contribute to the water barrier of the epidermis and where is it found?
lamellar bodies; stratum granulosum
where are the cells of your skin most acidic?
top layers of stratum corneum
what does UV exposure do that causes us to tan?
alters rate of melanin production thru activity of tyrosinase (increasing melanin production)
what is the difference between using sunscreen and what melanin does?
- sunscreen REFLECTS UV light
- melanin ABSORBS UV light
what are Langerhans cells?
dendritic antigen-presenting cells involved in delayed-type hypersensitivity reactions
what is a Merkel’s cell?
- touch receptor (modified epidermal cells)
- contain neurosecretory granules that can secrete neurotransmitters and activate nerves
- Merkel’s cell + associated neuron = Merkel’s corpuscle
what is the difference between thick and thin skin?
- thick = only on palms of hands and soles of feet (hairless); thick stratum corneum; visible stratum granulosum and sometime stratum lucidum
- thin = everywhere else; hair with sebaceous glands and sweat glands; usually cannot see stratum lucidum and sometimes stratum granulosum
what are the layers of the dermis?
- papillary = deep to epidermis
- reticular layer = between papillary layer and hypodermis
what does the papillary layer consist of?
loose CT, small nerves, Meissner’s corpuscles, collagen types I and II, elastic fibers
what are the differences between eccrine and apocrine sweat glands?
- eccrine = all regions of body except lips & external genitalia, duct has stratified cuboidal epithelium (empties product onto free surface), regulate body temp, long ducts, small lumen
- apocrine = axilla, areola/nipple, anal region, external genitalia, larger than eccrine w/ larger lumen, viscous secretion into hair follicle, short ducts, large lumen
what method of secretion do sebaceous glands use?
holocrine
nail plate corresponds to what?
stratum corneum
nail bed corresponds to what?
stratum spinosum & stratum basale
what does the reticular layer in the dermis consist of?
- reticular = dense irregular CT, large nerves & blood vessels, Pacinian corpuscles, hair follicles
what is the hypodermis and what is it made of?
- aka superficial fascia
- anchors skin to underlying tissue
- is the base of sweat glands and hair follicles
- made up of loose CT and adipose tissue
what is the Pacinian corpuscle for?
- deep pressure & vibrations
- amplification of senses
what are the 2 types of sensory structures?
1) Nonencapsulated = free nerve endings in epidermis; touch, pressure, heat/cold, pain; associated w/ hair follicles
2) Encapsulated = Ruffini ending (dermis); Meissner’s corpuscle (dermal papillae); Pacinian corpuscle (dermis & hypodermis)
what is the structure of mature hair?
- 3 layers: (1) medulla (thick hair) (2) cortex (3) cuticle (outermost)
- root sheath
- dermal sheath (CT surrounding follicle)
what is the structure of the nail?
- hard keratin
- hyponychium & eponychium are continuous w/ stratum corneum
