INTERGUMENTARY SYSTEM Version 2 Part 2

Bulb

A swelling at the base where hair originates in dermis or hypodermis.

Root

The remainder of the hair in the follicle.

Shaft

The portion above the skin surface.

Dermal Papilla

Bud of vascular connective tissue encased by bulb

Dermal Papillae

They are upward, finger-like extensions of dermis

Dermal Papilla

Only source of nutrition for hair

Hair matrix

region of mitotically active cells immediately above papilla

Hair matrix

Hair’s growth center

Follicle

A diagonal tube that extends into dermis and possibly hypodermis.

Epithelial root sheath

An Extension of the epidermis lying adjacent to hair root

Epithelial root sheath

It widens at deep end into bulge—source of stem cells for follicle growth

Connective tissue root sheath

Derived from dermis but a bit denser

Connective tissue root sheath

Surrounds epithelial root sheath

Hair receptors

sensory nerve fibers entwining follicles

Piloerector muscle

A smooth muscle attaching follicle to the dermis that contracts to make the hair stand on end (goosebumps). Also called the arrector pili.

Medulla

Core of loosely arranged cells and air spaces

Cortex

Constitutes bulk of the hair

Cortex

Consists of several layers of elongated keratinized cells

Cuticle

Composed of multiple layers of very thin, scaly cells that overlap each other. Free edges direct upward.

Medulla, Cortex, Cuticle

Three layers of the hair in cross section

Straight hair

round

Wavy hair

oval

Curly hair

Relatively flat

Color

due to pigment granules in the cells of the cortex

Brown and black hair

Hair color that is rich in eumelanin.

Red hair

Hair color that has high concentration of pheomelanin.

Blond hair

Hair color that has an intermediate amount of pheomelanin and very little eumelanin.

Gray and white hair

Hair color that has little or no melanin.

Anagen, Catagen, Telogen

Three stages of hair cycle

Anagen

growth stage where stem cells multiply.

Anagen

Stage where root sheath cells above papilla form hair cells of hair matrix

Anagen

Stage where hair cells make keratin and die as they are pushed upward

Catagen

Degeneration stage

Catagen

Stage where base of hair keratinizes into a hard club—club hair

Catagen

Stage where mitosis in hair matrix ceases and sheath cells below bulge die

Telogen

Resting stage

Telogen

Stage when papilla reaches the bulge.

Alopecia

thinning of the hair or baldness

Pattern baldness

hair lost from select regions

Baldness allele

Dominant in males and expressed when testosterone levels are high

Testosterone

It causes terminal hair on top of scalp to be replaced by vellus hair.

Hirsutism

Excessive or undesirable hairiness in areas that are not usually hairy

Nails

clear, hard derivatives of stratum corneum

Nails

Composed of thin, dead cells packed with hard keratin

Nail plate

hard part of the nail

Free edge

overhangs the fingertip

nail body

visible attached part of nail

Nail root

extends proximally under overlying skin

Nail fold

surrounding skin rising above nail

Nail groove

separates nail fold from nail plate

Nail bed

skin underlying the nail plate

Hyponchium

Epidermis of the nail bed

Nail matrix

Growth zone (mitotic) of thickened stratum basale at proximal end of nail

Lunule

opaque white crescent at proximal end of nail due to thickness of matrix

Eponychium

narrow zone of dead skin overhanging proximal end of nail. Also known as cuticle.

merocrine sweat glands, apocrine sweat glands, sebaceous glands, ceruminous glands, and mammary glands

5 types of glands the skin possesses