HAIR

1. Presence of hair is main feature of mammals, absent in whale fish.
2. Soft hair in embryo of animals are lanugo. Study of hair is tricology.
3. Part of hair which is outside epidermis is shaft.
4. Inner part remains in hair follicle is hair bulb or root.
5. Follicle at its base form hair papillae, rich in b.v. and nerve suply.
6. In these cells power of division present through out life.
7. Growth of hair depends on these cells. Around hair scally cuticle present.
8. Outer part of hair is cortex, fibrous in nature, melanin present in it when melanin is disappeared and tiny air bubbles come, hair turns white.
9. Inner part of hair is medulla made up of air filled, round, closely attached cells.
10. Hair is fixed in hair follicle by Henle's layer, Huxley's layer & Hyaline's layer.
11. Hair follicle is placed obliquely in dermis.
12. Attached to epidermis by arrector pilli or elevator pilli muscle or arrector polirum muscle.
13. This muscle is connected to sympathetic nervous system.
14. Arrector pilli are absent in eye brow, arm's pit & other parts.
15. In cold and fear, muscle is contracted, hair become straight i.e. cutis anserina.
16. This time skin looks like goose flesh or duck bumps.
17. It is under control of adrenalin. In rabbit & cat and other sliff hair are vibrissae.
18. In rabbit, thigmo receptor, meant to judge burrows at night.
19. In cat & rabbit if we cut vibrissae locomotion is uncontrolled & it can not run fast.
20. If we remove all hair from skin, sweating is increased.