Ch 6.2 Integumentary Structures Derived from Epidermis

The Catagen Phase

A brief regression period in hair growth where cell division ceases and the follicle undergoes involution.

Diffuse Hair Loss

A condition that is both dramatic and distressing, hair is shed from all parts of the scalp.

Visual Identification

A function of hair that aids in determining age and sex, and identifying individuals.

Sensory Reception

A function of hair that consists of associated tactile receptors (hair root plexuses) that detect light touch.

Chemical Signal Dispersal

A function of hair that helps disperse pheromones

Heat Retention

A function of hair that prevents the loss of conducted heat from the scalp to the surrounding air.

Protection

A function of hair that protects the scalp from sunburn and injury and entraps particles before they travel deeper into the respiratory system.

Eponychium (epi = upon, onyx = nail) also known as the cuticle

A narrow band of epidermis extending from the margin of the nail wall onto the nail body

Cuticle

A single cell layer around the cortex which coats the hair.

The Hair Matrix

A structure immediately adjacent to the hair papilla in the hair bulb.

The Hair Follicle

An oblique tube that surrounds the hair root. It always extends into the dermis and sometimes into the subcutaneous layer.

Stages Hair Growth Cycle

Anagen, Catagen, and Telogen

Alopecia (alopekia = a disease like fox mange)

Can occur in both sexes, usually as a result of aging.

Male Pattern Baldness

Causes loss of hair first from only the crown region of the scalp rather than uniformly. It is caused by a combination of genetic and hormonal influences.

Pheromones

Chemical signals involved in attracting members of the opposite sex and in sex recognition.

Terminal Hair

Coarser, pigmented, and longer than vellus. It grows on the scalp, and it is also the hair of eyebrows and eyelashes. At puberty, it replaces vellus hair in the axillary and pubic regions, and forms beards on the faves of males.

Apocrine Sweat Glands

Coiled, tubular glands that relies their secretion into hair follicles in the axillae, around the nipples, in the pubic region, and in the anal region. Produces secretion by exocytosis.

The Hair Papilla

Composed of a small amount of connective tissue containing tiny blood vessels and nerves.

Sweat

Consists of approximately 99% water and 1% other chemicals that include electrolytes, metabolites, and waste products.

The Hair Bulb

Consists of living epithelial cells and is a swelling at the base where the hair originates in the dermis.

Nail Plate

Consists of the free edge, nail body and nail root.

Hirsutism (hirsutus = shaggy)

Excessive male pattern harness in areas of the body that normally do not have terminal hair.

Factors that contribute to excessive hair loss

Exposure to drugs, dietary factors, high fever, or stress.

Arrector Pili

Extend from the hair follicle to the dermal papillae; are thin ribbons of smooth muscle. Upon stimulation, they contract, pulling the hair follicle and elevating the hair, producing "goose bumps."

Vellus (vellus = fleece)

Fine, non pigmented hair covering most of the fetal body; also found on the upper and lower limbs.

Lanugo

Fine, soft, unpigmented fetal hair.

Sebaceous Glands

Holocrine glands that produce an oily, waxy secretion called sebum that is usually discharged into a hair follicles and onto the hair itself.

Three kinds of hair we produce during our lives:

Lanugo, vellus, and terminal hair.

Ceruminous Glands

Modified apocrine sweat glands located only in the external acoustic meatus (ear canal), where their secretion forms a waterproof earwax called cerumen.

Mammary Glands

Modified sweat glands found in both males and females, but these glands become functional only in pregnant and lactating females, when they produce milk, a secretion that nourishes offspring.

Epidermal Derivatives (appendages of the integument)

Nails, hair, and exocrine glands of the skin.

The Medulla

Not found in all hair types; it is composed of loosely arranged cells and air spaces, and contains flexible, soft keratin.

Functions of Hair

Protection, Facial Expression, Heat retention, Sensory reception, Visual identification. Chemical signal dispersal.

Sebum

Secretion of a sebaceous gland that acts as a lubricant to keep the skin and hair from becoming dry, brittle, and cracked.

The Cortex

Several layers of flattened cells closer to the outer surface of the developing hair.

Cerumen

Soft, waxy secretion of the ceruminous gland; found in the external auditory meatus.

The Anagen Phase

The active phase of hair growth where living cells of the hair bulb are rapidly growing, dividing, and transforming into hair.

Nail Matrix

The acutely growing part of the nail.

Free Edge

The distal whitish part of the nail; appears white because there are no underlying capillaries

Nail Folds

The folds of skin along the lateral and proximal borders of the nail.

Three Zones of Hair

The hair bulb, root, and shaft

Epithelial Tissue Root Sheath

The inner layer of the hair follicle wall; originates from the epidermis.

Thermoregulation

The major function of merocrine sweat glands which aids in the regulation of body temperature by evaporation of fluid from the skin.

Merocrine (eccrine) Sweat Glands

The most numerous and widely distributed sweat glands. They are simple, coiled tubular glands that discharge their secretions directly onto the surface of the skin via exocytosis.

Sweat Pore

The opening of the sweat gland on the epidermal surface.

Connective Tissue Root Sheath

The outer layer of the hair follicle wall; originates from the dermis

Nail Body

The pinkish part of the nail; appears pink because of the underlying capillaries.

Facial Expression

The primary function of the hair of the eyebrows

Nail Root

The proximal part of the nail; embedded in the skin

The Telogen Phase

The resting phase of hair growth and is usually the phase where the hair is shed. (these hairs are the ones we find in our comb to brush.)

The Shaft

The third portion of the hair that extends beyond the skin surface; consists of dead epithelial cells

The Root

The zone of the hair extending from the bulb to the skin surface; consists of dead epithelial cells

Sweat Gland Duct

Transports te secretion to the surface in the epidermis (in a merocrine sweat glad) or into the hair follicle (in an apocrine sweat gland).

Lunula (luna = moon)

the whitish semilunar area of the proximal end of the nail body; It has a whitish appearance basale obscures the underlying blood vessels.