Integumentary System

Components of the Skin

size

location

contrast to mucous membranes

subcutaneous layer (superficial fascia; panniculus adiposus)

layers

epidermis

keratinocytes

specializations

keratohyaline

keratin

layers (from superficial to deep)

stratum corneum

stratum lucidum

stratum granulosum

stratum spinosum

stratum germinativum (basale)

melanocytes

melanin

APCs (antigen-presenting cells)

dermis

layers

papillary layer

reticular layer

fibers

collagen & elastin

nerve endings

free nerve endings

Merkel cell complexes

encapsulated nerve endings

Pacinian corpuscles

Meissner’s corpuscles

Ruffini corpuscles

Krause end bulbs

capillaries

adnexal structures

hair follicles

hair bulb

hair root

hair shaft

hair cycle

anagen

catagen

telogen

nails

hair bed

lunula

eponychium, hyponychium, & paronychium

nail disorders

Beau’s lines

glands

sebaceous glands

eccrine sweat glands

ceruminous glands

apocrine sweat glands

Meibomian glands

mammary glands

Homeostasis

protective barrier

regulation of body temperature

sensory reception

water balance

synthesis of vitamins & hormones

absorption of materials

Sensory reception

nociceptors

pressure

Pacinian corpuscles

light touch

Meissner’s corpuscles

temperature

hot & cold

Synthetic activities

pigments

melanin

carotene

aids in formation of vitamin D₃

Selective permeability

fat-soluble substances

vitamins A, D, E, & K

steroids, such as estrogen

use of patches to deliver drugs through the skin

estrogen

scopolamine

nitroglycerin

nicotine

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Questions for thought
1.		Why are there no skin cancers that originate from cells of the stratum corneum?
2.		Explain the following familiar phenomena: (a) pimples, (b) dandruff, (c) greasy hair, (d) fingerprints.
3.		Is a bald man hairless? Explain.
4.		Why does skin wrinkle, and what factors accelerate the wrinkling process?
5.		In our society, a tan body is associated with good heath. Medical research, however, constantly warns about the dangers of excessive exposure to the sun. What are the benefits of sun exposure? What are its dangers?
6.		What are the two major layers of the dermis, and what are the components of each?
7.		Describe the mechanisms the skin has to cope with the possibility of bacterial infection.

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