5. Integumentary System

What are arrector pili? What do they do?

What is the function of the arrector pili muscles?

Describe the process of hair formation, and list several factors that may influencea. growth cycles andb. hair texture.

Tanya, a 30-year-old resident of a mental hospital, has an abnormal growth of hair on the dorsum of her right index finger. The orderly comments that she gnaws on that finger continuously. What do you think is the relationship between Tanya's gnawing activity and her hairy finger?

Many people change the natural appearance of their hair, either by coloring it or by altering the degree of curl in it. Which layers of the hair do you suppose are affected by the chemicals added during these procedures? Why are the effects of the procedures not permanent?