Epidermis: stratified squamous epithelium
Dermis: connective tissue (loose and dense irregular)
Hypodermis: loose CT….mainly adipose tissue. (called superficial fascia in gross
Derivatives of skin include sweat glands, hair, sebaceous glands and nails.
2) prevent water loss
3) PNS receptors
4) Vitamin D production
5) Heat regulation
6) Waste product secretion
7) Immunologic functions – Langerhans cells – antigen processing
Thick skin is glabrous, without hair. Thin skin has hair.
- thick and thin refer to epidermis only.
- Thick skin has a thinner dermis than thin skin
- Thick skin found on palms and soles of feet.
Thick skin: 5 layers:
1) stratum basale=stratum germinativum
a. progenitor cells constantly renew epithelium
2) stratum spinosum
a. Nodes of Bizzozzaro = desmosomes
3) stratum granulosum
a. keratohyalin granules
4) stratum lucidum
a. eosinophilic refractile cells containing large amounts of
keratin…nuclei not visible. Only in thick skin.
5) stratum corneum
a. no cytoplasmic organelles
b. cell membranes coated with glycolipid (acylglucosylceramide)
c. gets thicker when exposed to more wear and tear: callus formation
- dermal papillae
- epidermal ridges
- interpapillary pegs: down growth of epidermis into dermis where sweat
duct passes from dermis to epidermis
- dermal ridges: form basis for fingerprints - basal cells attach to dermis via hemidesmosomes: attach to b