Hair and Sebaceous Glands
Hair matrix
actively dividing area of the hair bulb that produces the hair
Hair Follicle
an accessory structure of the integument; a tube, lined by stratified squamous epithelium
Why does puberty spark an increase in acne for many?
because adrenal glands increase production of androgens, which stimulate increased secretion of sebum
What happens if sebaceous ducts become blocked?
causes inflammation and a raised "pimple"
What type of secretion mechanism releases sebum?
contraction of the arrector pili muscle
What causes the stimulation of the arrector pili muscle?
contractions by emotional status or a response to cold
Sebaceous Gland (oil gland)
discharge an oily lipid secretion into the hair follicle or, in some cases, onto the skin
What is the main cause of acne?
excess sebum and squamous epithelial cells clogging the glands
Arrector Pili Muscle
extends from papillary layer to the connective tissue sheaths. When stimulated, it pulls on the follicle, forcing the hair to stand up.
What are some influences on hair color?
genetics, hormonal and environmental factors
What are sebaceous follicles and where are they located?
large sebaceous glands that discharge sebum directly onto the skin. Located on the face, back, chest, nipples, and external genitalin
How are the amounts of estrogen or testosterone related to hair loss?
lower amounts increases hair loss
What is the role of sebum?
lubricates the hair and skin to prevent the growth of bacteria
Cuticle (the surface layer)
made up of an overlapping shingle-like layer of cells
Medulla
makes up the core of the hair
How much does hair on the scalp grow a day?
.3 mm
How many hairs a day do we lose?
20-100 hairs a day
What is the scientific name for baldness?
Androgenic alopecia
What cell layers make up the hair follicle?
Dermis and hypodermis
What type of gland is a sebaceous gland?
Exocrine Glands
How long is the growth phase? Resting Phase?
Growth: 2-6 years Resting: 2-3 months
What is a hair follicle? Where is it found?
Hair follicle is an accessory structure of the integument; a tube, lined by stratified squamous epithelium. Begins at the surface of the skin and ends at the hair papilla.
Where are the pigment producing melanocytes located to produce hair color?
Hair papilla
What are some factors that influence the appearance of hair?
Size and shape of the follicles
How is a pimple formed?
a clogged sebaceous gland draws in anaerobic bacteria that signals the immune system to trigger inflammation, and raises that area of skin
What is acne vulgaris?
a disorder of the sebaceous glands
Hair Papilla
a peg of connective tissue containing capillaries and nerves
Is hair living or nonliving?
nonliving
How come elderly people have gray hair?
pigment production decreases with age
...in the nose? eyelashes? external ear?
prevents the entry of foreign particles
What are the functions of the hair on the scalp?
protect from UV light, cushion a light blow, and provide insulating benefits for the skin
Hair shaft
the part we see on the surface
Hair root
the portion that anchors the hair into the skin
Where is hair not found on the body?
the sides and soles of the feet, palms of the hands, sides of fingers and toes, the lips, and portions of the external genital organs
Cortex
the underlying layer
