1. Integumentary System Notes
Unit 3 Tissues, Membranes and Integumentary System

2. Anatomy Epidermis (outside) Skin Dermis (inside)
Subcutaneous layer or hypodermis

5. Epidermis Stratum basale (stratum germinativum)
Innermost layer
Reproduce themselves & allow the skin to repair itself
Stem cells that produce keratin
Tough waterproof material, provides cells in outer layer with a protective quality
Melanocytes - # the same for all races, concentration is different
Melanin produced in a melanosome

6. Stratum spinosum (thorn- like, prickly)
8-10 layers attached by desmosomes
See spines when cell is stained for microscopy
Keratinocytes take in melanin by cytocrine secretion

7. Stratum granulosum 3-5 layers Keratinization begins here
Keratohyalin found in granules
Cells beginning to die

8. Stratum lucidum (lucid = clear)
More apparent in thick skin
3-5 layers of clear cells
Eleidin
Stratum corneum (corneum means horny)
Dead, flat cells full of keratin
Keratin is waterproof
Cells are shed
Basal cell to surface – about 2-4 weeks

10. Skin color Same number of melanocytes Albinism Uv light or x-rays
Genetic factors
Same number of melanocytes
Albinism
Environmental factors
Uv light or x-rays

11. Physiological factors
Amount of blood
Amount of oxygen
Cyanosis
Carotene accumulation
Jaundice – liver disorder

15. Dermis Deeper & thicker than the Epidermis
Connective tissue layer, cells scattered far apart
Collagen and elastic fibers
Papillary layer
1/5 of dermis – loose areolar connective tissue
Highly vascular
Dermal papillae - fingerprints
Wrinkles develop as the skin loses elasticity and sags

16. Reticular (net) layer Dense irregular connective tissue
Sebaceous (oil) glands
Hair follicles
Ducts of sudoriferous (sweat) glands
Striae or stretch marks
Nerves and nerve endings to sense pain, pressure, touch, and temperature

17. Hypodermis Attaches the reticular layer to the underlying organs
Loose connective tissue and adipose tissue
Major blood vessels – rete cutaneum

18. Appendages of the Skin Hairs
Epidermal growths that function in protection
Shaft, root, and follicle
Soft newborn hair is called lanugo
Arrector pili muscle – “erectors of the hair”
Sebaceous glands – secrete oil

22. Receptors
Meissner’s corpuscle – located close to the skin surface, detects light touch
Pacinian corpuscle – deep in the dermis, detects pressure on the skin surface

23. Nails Plates of highly packed, keratinized cells
Protection, scratching, & manipulation
Formed by cells in nail bed called the matrix ( in area of lunula)
1 mm / week

26. Skin Glands Sebaceous (oil) glands Sweat (sudoriferous) glands
Usually connected to hair follicles
Moistens hair and waterproofs skin
Sweat (sudoriferous) glands
Eccrine sweat glands – most numerous
Secrete Water, salt, wastes
Function is to cool the body (also nervous)
-Apocrine sweat glands
Associated with hair follicles
More viscous – fatty acids and proteins
Odor occurs when broken down by bacteria

27. Ceruminous glands Modified sudoriferous glands
Secrete cerumen (ear wax)
Mammary glands
Secrete milk