Integument Flashcards
The skin and derivations/appendages make up the __ and ___ organ in the body
largest and heaviest
What % total body weight is the skin?
16
What are the 7 main functions of the skin? (dont need to explain)
- protective
- Immunological
- Sensory
- Exocrine
- Endocrine
- Homeostasis
- Communication
How is the skin protective?
water resistant barrier that protects against dehydration, abrasions, UV light, and toxins
How is the skin immunological?
acts as a passive barrier to pathogens but also contains APCs
What kind of exocrine activity does the skin have? (4 kinds)
Eccrine sweat glands for excretion and cooling
Apocrine sweat glands for signalling
Sebaceous glands for lubrication
Mammary glands for nutrition
What is an endocrine function of the skin?
part of the vitamin D synthesis pathway occurs here
What are some homeostatic functions of the skin?
Thermoregulation, water conservation, gas exchange, and excretion
What are some “communication” roles of the skin?
Non-verbal signals like changes in coloration and goosebumps
The most superficial later of the skin is the…?
epidermis
What is the predominant cells type of the epidermis?
Keratinocytes (90%)
Besides keratinocytes, what 3 other cell types make up the epidermis?
- Melanocytes
- Langerhans cells
- Merkel cells
regeneration of the epidermis occurs approximately every…
30 days
The epidermis is avascular, how then is it nourished?
Receives nourishment from vessels in the underlying dermis
What is the only kind of innervation that the epidermis receives?
Unencapsulated (free) nerve endings
the epidermal layer is further subdivided into how many strata?
5
What is the order of the epidermal strata from outer to inner?
- Stratum corneum
- Stratum lucidum
- Stratum granulosum
- Stratum spinosum
- Stratum basale
Which strata isn’t always present in the epidermis?
the stratum lucidum
Where does the division of the keratinocytes occur?
in the stratum basale
what are two main divisions of types of skin? where is each found
thick and thin
- depends on location
- thick is only on the palms of hands and the soles of feet
What is the difference between thick and thin skin in terms of layers? in terms of functions?
the thick skin has all 5
- has abundant sweat glands
- more squamous stratum spinosum cells
thin skin has 4 layers
- stratum lucidum not always detectable
- has hairs
The turnover of the skin surface is made up of 4 overlapping processes: what are they?
- Cell renewal (mitosis)
- Differentiation (keratinization)
- Cell death
- Exfoliation
How long does the keratinization process take? is it totally synchronized?
takes about 15-30 days and occurs in waves
cell layer produced by a mitotic wave in the basal layer undergoes keratinization in synchrony
What is the stratum basale comprised of and what does it rest on?
Single later of columnar cells that sit on the basal lamina