KIN 6.2-6.3

spot baldness for the circular bald patches that develop on the scalp or the body, can occur in all individuals, regardless of sex; this condition is an autoimmune disorder where the body mistakes selected hair follicles as foreign and attacks them

alopecia areata

the active phase of growth where living cells of the hair bulb are rapidly growing, dividing, and transforming into hair; longest part of the growth cycle and lasts from about 18 months to as much as 7 years; during this phase each hair strand prows about one third of a millimeter per day

anagen phase

Stages of hair growth

anagen, catagen, telogen

coiled/tubular secretory portion located in reticular layer of dermis; viscous and cloudy secretions containing proteins and lipids go into a hair follicle, in the axillae, around the nipples, in the pubic region, and in the anal region

apocrine sweat glands

thin ribbons of smooth muscle extending from the hair follicle to the dermal papillae

arrector pili

run horizontally across the nail and indicate a temporary interference with nail growth at the time this portion of the nail was formed

beau's lines

prone to vertical splitting and separation of the nail plate layers at the free edge; can be caused by overexposure to water or to certain household chemicals

brittle nails

brief regression period where cell division ceases and the follicle undergoes involution. This very short phase lasts for about 3 to 4 weeks

catagen phase

Soft, waxy secretion of the ceruminous gland; found in the external acoustic meatus; helps trap foreign particles or small insects and keeps them from reaching eardrum

cerumen

modified apocrine sweat glands located only in the external acoustic meatus (ear canal); secretion forms ear wax called cerumen

ceruminous glands

scar tissue is composed of:

collagen fibers

originates from dermis

connective tissue root sheath

cells of the follicle walls are organized into 2 concentric layers called

connective tissue root sheath and epithelial tissue root sheath

formed by several layers of flattened cells closer to the outer surface of the developing hair; single layer around this area forms the cuticle that coats the hair

cortex

hair is shed from all parts of the scalp

diffuse hair loss

originates from epidermis

epithelial tissue root sheath

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

eponychium

Formation of fibrous connective tissue as a repair or reactive process; when regeneration is not possible because part of the organ is too severely damaged or its cells lack the capacity to divide, the body fills in the gap with scar tissue

fibrosis

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

hair bulb

an oblique tube that surrounds the hair root; always extends into the dermis and sometimes into the subcutaneous layer

hair follicle

a structure immediately adjacent to the hair papilla in the hair bulb; Epithelial cells near the center of this area divide, producing new cells that are gradually pushed toward the surface

hair matrix

epithelium at the base of the bulb surrounds this; composed of a small amount of connective tissue containing tiny blood vessels and nerves

hair papilla

excessive hairiness in body areas that normally do not have terminal hair

hirsutism

the area of thickened epithelium underlying the free edge of the nail

hyponychium

occurs when the edge of a nail digs into the skin around

ingrown nail

fine, soft, unpigmented fetal hair

lanugo

whitish, semilunar area of proximal end of nail body; lighter-colored appearance because a thickened stratum basale obscures the underlying blood vessels

lunula

causes loss of hair first from only the crown region of the scalp rather than uniformly; caused by a combination of genetic and hormonal influences

male pattern baldness

modified apocrine sweat glands that both males and females have but are only active during pregnancy and lactating females; secretions are controlled by a complex interaction between gonadal and pituitary hormones

mammary glands

not found in all hair types, is a remnant of the soft core of the matrix; composed of loosely arranged cells and air spaces, and it contains flexible, soft keratin

medulla

types of sweat glands

merocrine/eccrine and apocrine

coiled/tubular secretory portion located in reticular layer of dermis; clear secretions that are mostly water go to surface of epidermis; thermoregulation function

merocrine/eccrine sweat glands

specialized epithelial cells are sandwiched between the secretory gland cells and the underlying basement membrane; in response to nervous system stimulation, these cells contract to squeeze the gland, causing it to discharge its accumulated secretions

myoepithelial cells

contains deeper, living cells of epidermis

nail body

the tip of the finger enlarges and the edges of the nail grow and curve around the tip; occurs over a period of years and is indicative of hypoxia

nail clubbing

overlap the nail; along lateral and proximal borders of nail

nail fold

actively growing part of the nail; nail bed thickens to form this

nail matrix

refers to tiny depressions or shallow holes that appear in the nail body; usually is a symptom of another disorder, such as psoriasis, alopecia areata, dermatitis, or a connective tissue disorder

nail pitting

scalelike modifications of the stratum corneum layer of the epidermis that form on the dorsal edges of the fingers and toes; protect distal tips

nails

fungal infection that occurs in nails constantly exposed to warmth and moisture; eventually causes a yellowish discoloration, a thickened nail, and brittle, cracked edges

onychomycosis

free edge, nail body, nail root, nail matrix, nail plate, nail body, eponychium, hyponychium, lunula, nail fold

parts of nail

free edge, nail body, nail root

parts of nail plate

single hair; composed of keratinized cells growing from hair follicles that extend into the dermis, and often deeper into the underlying subcutaneous layer

pilus

functions of hair

protection, heat retention, sensory reception, visual identification

the replacement of damaged or dead cells with the same cell type by cell division

regeneration

Two ways damaged tissue can be repaired

regeneration and fibrosis

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

root

holocrine glands that produce an oily, waxy secretion called sebum; inactive during childhood but become active during puberty

sebaceous glands

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

shaft

nail malformation where the outer surface of the nails are concave instead of convex; frequently are a sign of an iron deficiency

spoon nails

transports secretion to surface of epidermis (merocrine) or into a hair follicle (apocrine)

sweat gland duct

an indented region on the opening of the sweat gland duct on the epidermal surface

sweat pore

resting phase and is usually the phase when the hair is shed; after 3 to 4 months in this phase, the cells of the hair bulb start regrowing, and the follicle reenters the anagen phase

telogen phase

usually coarser, pigmented, and longer than vellus; grows on the scalp, and it is the hair of eyebrows and eyelashes; at puberty replaces vellus hair in the axillary and pubic regions, and under the influence of testosterone it will form a beard on the face

terminal hair

differences in hair density are due primarily to differences in its ______ and ______

texture and pigmentation

Fine, nonpigmented hair covering most of the fetal body; replaces most of lanugo at birth; primary human hair and is found on the upper and lower limbs

vellus

occurs when growth and thickening of the nail slows or stops completely; as the nail growth slows, the nails become yellowish or sometimes greenish; often, but not always, may be an outward sign of respiratory disease

yellow nail syndrome

Hair bulb, root, shaft

3 zones along length of hair