1. Hair Types Lanuga Vellus Terminal Fetal hair Delicate, unpigmented
Short, fine, unpigmented
Covers body
Males- replaced with terminal hair on face during puberty
Terminal
Covers fetus near birth
Long, coarse, pigmented
Scalp, eyelashes, eyebrow

2. Hair: What is it? Dead, keratinized epithelial cells
Is composed of 3 layers:
Medulla
Central axis
2-3 layers of soft keratin
Cortex
Forms the bulk of the hair
Hard keratin
Cuticle
Single layer of cells filled with keratin
Edges overlap like shingles

3. Hair Has three components Shaft Root Hair bulb
Above skin
Root
Below skin
Hair bulb
Area of growth
The hair rests in a hair follicle

4. Hair Follicle (The area in which the hair rests)
Consists of 2 parts
1. Dermal root sheath
Portion of the dermis that surrounds the
follicle
Outermost layer
2. Epithelial root sheath
External portion
Has all 4 strata of thin skin at the opening of the follicle
Deeper in the hair follicle, only strata spinosum and basale
Helpful for regrowth during damage
Internal portion
Holds hair in place
Comes out when you remove a hair (the white tissue around the hair)

6. Hair Bulb The hair bulb is at the base of the hair root.
Inside bulb is a mass of undifferentiated epithelial cells = matrix
Dermis projects into bulb as a papilla and provides nourishment to cells of matrix

7. Hair Growth has two stages.
Growth stage
Matrix cells differentiate, become keratinized, and die
Hair grows as cells are added at hair root
Eventually growth stops, follicle shortens, and falls out
Resting stage
New hair replaces old hair that fell out

8. Interesting Facts about hair growth
Eyelashes – 30 days grow and 105 days rest Scalp – 3 years growth and 1-2 years rest At any given time, 90% of scalp hairs are growing 100 hairs lost every day

9. Hair color Melanin from melanocytes in matrix
Amount/ type determine color
Grey hair is from lack of melanin production

10. Arrector pili muscle Smooth muscle tissue
Contraction causes a pull on hair follicle to cause “Goosebumps”
Cold- to trap air and insolate
Scared- to appear larger in size

11. Nails
Protects digits
Used for scratching and Grasping

12. Nail structures Nail root Nail body Nail fold Nail groove Eponychium
Below skin
Nail body
Visible portion of the nail
Nail fold
Skin covering the lateral and proximal edges of the nail
Nail groove
Holds the nail in place
Eponychium
Cuticle
Hyponychium
The skin underneath the free edge

13. Nail growth Nail bed Nail matrix
Area that nail root and body attaches to
Visible and appears pink because of blood vessels in the dermis
Nail matrix
Matrix made of stratum germantivum (epidermis)
Nail cells are produced in the matrix and are pushed distally over the nail bed (Just like hair and skin)
Matrix makes up the lanula, the whitish, crescent shaped area (thicker therefore you cannot see the blood vessels)
Grow mm per day

14. Glands Sebaceous In the dermis Produce Sebum Holocrine
A oily and white substance rich in lipids
Holocrine
Connected by a duct to upper part of hair follicle
Prevents drying, protection against bacteria

15. Sweat glands Merocrine Open to surface through sweat pores 2 parts
Deep coiled part produces a watery, isotonic fluid with salt
As it moves through duct, the salt leaves the duct and stays in body to conserve salt
Hyposmotic fluid is excreted through pores
Sweat evaporated to cool body

16. Sweat glands Apocrine Opens before reaching surface
Secretions are organic substances, odorless
When secretions are metabolized by bacteria, odors are released (body odor)

17. Aging Decrease elastic fibers
Decrease fat in hypodermis (sagging and wrinkle)
Decrease sebaceous gland production (dry skin)
Decrease in melanocytes (white hair)
Some may increase (age spots)