Name 5 skin appendages.
Hair
Hair follicles
Nails
Sweat glands
Oil glands
What is the main function of body hair?
To sense insects before they bite or sting.
What are three reasons for having hair on your head?
Guards against head trauma, heat loss, and sunlight
What are flexible strands produced by hair follicles?
Hairs
What is another word for hairs?
Pili
What are the chief regions of the hair?
The shaft and root
In the shaft, keratinization is ________, but in the root, keratinization is ________.
Complete...
Still ongoing
What are the three concentric layers of keratinized cells in a hair?
Medulla, cortex, cuticle
Which of the three is absent from fine hairs?
The medulla
The _______ consists of large cells and airspaces.
Medulla
What's the bulky layer surrounding the medulla?
The cortex
The ________ is formed from a single layer of cells overlapping one another.
Cuticle
When the cuticle wears away at the tip of the hair shaft, allowing keratin fibrils in the cortex and medulla to frizz out. This is called a ________.
Split end
Hair pigment is made by _______ at the base of the hair follicle, and transferred to the cortical cells.
Melanocytes
How is red hair colored?
By an iron-containing pigment called trichosiderin
When melanin production decreases, and air bubbles replace melanin in the hair shaft, the hair ________.
Turns gray (or white)
________ fold down from the epidermal surface into the dermis.
Hair follicles
The deep end of the follicle expands to form a ________.
Hair bulb
A knot of sensory nerve endings is called a ________.
Hair follicle receptor
A hair follicle receptor is also called a ________.
Hair root plexus
A hair follicle receptor or hair root plexus wraps around each _______.
Hair bulb
________ is a nipplelike bit of dermal tissue that protrudes into the hair bulb.
Hair papilla
What supplies nutrients to the growing hair and signals it to grow?
Papilla
The wall of the hair follicle is composed of what 3 things?
The outer peripheral connective tissue sheath
The inner epithelial root sheath
A glassy membrane
The actively dividing area of the hair bulb that produces the hair is the ________.
Hair matrix
The hair matrix originates from the _____ _____.
Hair bulge
The two classifications of hair are:
Vellus
Terminal
The coarse, longer hair is ________, and pale, fine hair is _________.
Terminal...
Vellus
Terminal hairs of puberty grow in response to the effects of ________.
Androgens
What is excessive hairiness called?
Hirsutism
Hair thinning and some degree of baldness is called ________.
Alopecia
________ is when the immune system attacks the follicles and the hair falls out in patches.
Alopecia areata
The white crescent of the nail is called:
Lunule
The borders of the nails are overlapped by skinfolds called ________.
Nail folds
The fold that projects onto the body is the ________.
Cuticle
The thickened region beneath the free edge of the nail is the ________.
Hyponychium
Sweat glands are also called ________.
Sudoriferous glands
How many sweat glands does the average person have?
Up to 3 million
What are the two types of sweat glands?
Eccrine
Apocrine
Eccrine sweat glands are also called _______.
Merocrine sweat glands
Sweat is 99% ________.
Water, salts, vitamin C, antibodies, dermcidin, and traces of metabolic waste.
Sweat is _______, with a Ph between ___ and ___.
Acidic...
4 and 6
________ glands begin functioning at puberty and play little role in maintaining a constant body temp.
Apocrine
Modified apochrine glands found in the lining of the external ear canal
Ceruminous
Oil glands are also called ________ glands.
Sebaceous
True or False:
Sebaceous glands are also found in the thick skin of the palms and soles.
False
Sebaceous glands are found all over the body except the thick skin. Eccrine glands are particularly abundant on the palms and soles.
Sebaceous glands produce an oily substance called ________.
Sebum
Overactive sebaceous glands can cause ________ in infants. This is also called _______.
Seborrhea...
Cradle cap