pink part of the nail
the distal white nail ending
the whitish semilunar area of the proximal end of the nail body. It appears whitish because a thickened underlying stratum basale obscures the underlying blood vessels.
the skin on the lateral and proximal sides of the nail
a narrow band of epidermis that extends from the margin of the nail wall onto the nail body.
what the nail covers contains only the deeper, living cell layers of the epidermis.
the proximal part of the nail embedded in the skin.
the actively growing part of the nail-where the nail root thickens.
the region of thickened stratum corneum over which the free nail edge project.
together, the nail root, nail body, and the free edge make up the nail plate.
a fine, unpigmented, downy hair that first appears on the fetus in the last trimester of development.
at birth, most of the lanugo has been replaced by similarly fine, unpigmented or lightly pigmented hair called vellus- the PRIMARY human hair that is found on most of the body.
the coarser, pigmented, and longer hair that grows on the scalp, eyebrows, eyelashes, pubic area(during puberty it replaces pubic vellus), beards, arms, legs, and trunk of males.
1. Hair bulb-
consists of epithelial cells and is a swelling at the base where the hair originates in the dermis. The hair papilla is surrounded by the epithelium at the base of the bulb and is composed of a small amount of connective tissue containing tiny blood vessels and nerves.
2. Hair root
the hair within the follicle internal to the skin surface.
3. Hair shaft
The portion of the hair that extends beyond the skin surface.
where the specialized type of keratinization occurs.
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 contains flexible, soft keratin.
the relatively hard middle layer formed by several layers of flattened cells.
multiple layers around the hair cortex forms the cuticle, which coats the entire hair. The free edges of the cuticle cells are directed externally.
an oblique tube that surrounds the root hair that always extends into the dermis and sometimes into the subcutaneous layer.
Internal root sheath-
produced by peripheral cells of the matrix that surrounds both the hair and the deep part of the shaft, does not extend the entire length of the follicle because its cells are quickly destroyed.
External root sheath-
extends between the skin surface and the hair matrix. It contains the same epidermal cell layers as the skin surface.
ARRECTOR PILI MUSCLES-
ribbons of smooth muscle that are stimulated in response to an emotional state, like fear or anger, or exposure to the cold. They are responsible for elevating the hair and causing goose bumps.
Functions of hair include-
protection, heat retention, facial expression, sensory reception, visual identification, and chemical signal dispersal (pheromones that attract members of the opposite sex).
3 stages of the hair growth cycle:
1. Anagen phase (active phase of growth where living cells of the hair bulb are rapidly growing, dividing, and transforming into hair, longest stage) 2. Catagen phase (brief regression period where cell division ceases, shortest phase) 3. Telogen phase (the resting phase, usually the phase where hair is shed).
thinning of the hair that can occur in both sexes due to aging.
Diffuse hair loss-
a dramatic condition where hair is shed from all parts of the scalp, primarily a woman's issue which may be due to hormones, drugs, or iron deficiency.
distributed in axillary, anal, areolar, and pubic regions. Produces viscous, complex secretion; secretion influenced by hormones; may act as signaling/communication.
distributed throughout the body, except external genitalia, nipples, and lips; especially prevalent on palms, soles, and forehead. Produces nonviscous, watery secretion; controlled by nervous system; provides some antibacterial protection; functions in thermoregulation and excretion; flush surface of epidermis.
associated with hair follicles. Produces lipid material called sebum, which coats epidermis and shaft of hair; provides lubrication and antibacterial activity.
external acoustic meatus (external ear canal) that secretes cerumen (ear wax)
in breasts, produces milk.
3 functions of merocrine sweat glands-
1. Thermoregulation 2. Secretion (rids body of excess water, electrolytes, metabolites, and wastes) 3. Protection (dilutes harmful chemicals)
replaces damaged or dead cells with the same cell type and restores organ function.
when regeneration is not possible, fibrosis occurs (scar tissue is created). Full function is not restored.
a vascular connective tissue that initially forms in a healing wound.