Chapter 5: Hair, Nails, Glands, & Functions of Skin

what is hair?

consists of hard, flexible, dead keratinized cells,

What are the functions of hair?

• Warn of insects on skin

• Hair on head guards against physical trauma

• Protect from heat loss

• Shield skin from sunlight

what is the shaft?

area that extends above scalp, where keratinization is complete

what is the root?

area within scalp, where keratinization is still going on

what are the three parts to the hair shaft?

medulla, cortex, cuticle

what is the medulla?

central core, not present in fine hairs

what is the cortex?

several layers of flattened cells surrounding the medulla

what is the cuticle?

outer layer consisting of overlapping layers of single cells

where are hair pigments made?

melanocytes in hair follicles

what is red hair made by?

additional pheomelanin pigment

how is gray hair made?

when melanin production decreases and air bubbles replace melanin in shaft

what is the hair bulb?

expanded area at deep end of follicle

what is the wall of follicle composed of?

Peripheral connective tissue sheath, Glassy membrane, Epithelial root sheath

what is the peripheral connective tissue sheath?

• Derived from dermis

• Also called fibrous sheath

what is the glassy membrane?

acts like a basement membrane, located in between the epithelial root sheath and peripheral connective tissue sheath

what is the epithelial root sheath?

• Derived from epidermis

• Has external (continuation of epidermis) and internal (derived from matrix cells)

what is the hair matrix?

actively dividing area of bulb that produces hair cells

• As matrix makes new cells, it pushes older ones upward

what is hair papilla?

Dermal tissue containing a knot of capillaries that supplies nutrients to growing hai

what are the 2 types of hair growth?

vellus hair, terminal hair

what is vellus hair?

pale, fine body hair of children and adult females

what is terminal hair?

coarse, long hair

Found on scalp and eyebrows, face and neck of males

At puberty

• Appear in axillary and pubic regions of both sexes

what does the nail protect?

distal and dorsal surface of fingers and toes

what is the nail matrix?

thickened portion of bed responsible for nail growth

what is the nail fold?

skin folds that overlap border of nail

what is the eponychium?

nail fold that projects onto surface of nail body

Aka cuticle

what is the hyponychium?

area under free edge of plate that accumulates dirt

what is the part of the nail that contains a thickened nail matrix and appears white?

lunule, abnormal color or shape is an indicator of disease

What is another name for sweat glands?

sudoriferous glands

what are the 2 main types of sweat glands?

1. Eccrine (merocrine) sweat glands

2. Apocrine sweat glands

what type of cells do sweat glands have?

myoepithelial, Contract upon nervous system stimulation to force sweat into ducts (exocrine gland)

what sweat gland is the most numerous type and is located on palms, soles, and forehead?

Eccrine (Merocrine) Sweat Glands

where do Eccrine (Merocrine) Sweat Glands open to?

open directly on the skin’s surface, they secrete sweat

where can you find apocrine sweat glands?

Confined to axillary and anogenital areas

what do apocrine sweat glands secrete?

viscous milky or yellowish sweat that contains fatty substances and proteins (BO)

where do apocrine sweat glands empty into?

hair follicles which being to function at puberty

what are two modified apocrine glands?

ceruminous and mammary glands

what are ceruminous glands?

lining of external ear canal; secrete cerumen (earwax)

what do mammary glands do?

secrete milk

where can you find sebaceous (oil) glands?

Widely distributed, except for thick skin of palms and soles on hair follicles and secrete into hair follicles

how do sebaceous (oil) glands activate?

• Relatively inactive until puberty

  • Stimulated by hormones, especially androgens

what do sebaceous glands secrete?

sebum

• Oily holocrine secretion

• Bactericidal (bacteria-killing) properties

• Softens hair and skin

Petite

Rhinos

Can’t

Mimic

Big

Elephants

Protection

Regulation of body temperature

Cutaneous sensations

Metabolic functions

Blood reservoir

Excretion of wastes

what are the three barriers of skin?

Chemical barrier

Physical barrier

Biological barrier

what is the chemical barrier?

Skin secretions to inhibit bacterial growth or kill bacteria

Melanin provides a chemical barrier against UV radiation damage

what is the physical barrier?

Provided by the continuity of the skin and the hardness of the keratinized cells

what is the biological barrier?

Dendritic cells and macrophages to stimulate immune response

what is insensible perspiration?

resting body temperature, sweat glands produce about 0.5L of unnoticeable sweat per day

what is sensible perspiration?

to cool the body, sweat gland activity increases to produce up to 3 gallons of noticeable sweat

what are Cutaneous sensory receptors a part of?

nervous system

what is cutaneous sensation?

Respond to stimuli outside body, such as temperature and touch

what do metabolic functions do?

Skin provides the metabolic function of making Vitamin D

• important for absorption of calcium

• stimulated by the sunlight

what does it mean when the skin is blood reservoir?

Skin can hold up to 5% of the body’s total blood volume

Blood can be diverted to other areas of the body if needed

what is excretion?

Skin can secrete limited amounts of nitrogen-containing wastes, such as ammonia, urea, and uric acid (most of these wastes are excreted via urine)

Sweating eliminates excess water and salts