Hair and Nails

Question 1

What is the function of hair?

Answer 1

Protection against external factors
Sebum
apocrine sweat
social and sexual interaction 
thermoregulation
epithelial and melanocyte stem cell reservoir

Question 2

Where are terminal hairs found?

Answer 2

On scalp, eyebrows and eyelashes

Question 3

Where are vellus hairs found?

Answer 3

On the rest of the body ( - scalp, eyebrows and eyelashes) but not on palsm, soles, mucosal region of lips and genitalia
this is thin, pale hair

Question 4

Outline the hair cycle

Answer 4

Anagen: Where new hair forms and grows ~ 85% of hair. this phase lasts 2-6 years under normal conditions

Catagen: Regressing phase (1% of hair, lasts 3 week) : hair shrinking

Telogen: Resting phase (10-15% of hair, lasts 3 months)
blood supply from hair is lost and so loss of old hair

Question 5

Can the hair cycle occur in any order?

Answer 5

no, strict order. telogen only after catagen which is only after anagen

Question 6

Describe the structure of hair

Answer 6

skin has pilosebaceous follicles and sweat glands:
hair = piloseb unit - sebaceous gland & hair
epithelium pockets are continuous w superficial dermis
small papilla of dermis at base

Question 7

What is the arrector pili?

Answer 7

Smooth muscle that lifts up hair which is imp in thermoregulation

Question 8

Holocrine sebaceous glands?

Answer 8

open into pilary canal - in axillae follicles associagted w apocrine glands

Question 9

Infudibulum?

Answer 9

Upper most portion, form opening of of sebaceous gland to skin surface

Question 10

isthmus?

Answer 10

lower portion of upper part, between opening of sebaceous gland and arrector