Structure and function of hair

Question 1

Where does all hair develop from?

Answer 1

Hair develops from the epidermis

Question 2

What is the basic structure of hair?

Answer 2

long thin chains of keratin, composed of a central medulla, thick cortex and outer cuticle

Question 3

What are the three basic hair forms?

Answer 3

Stiff guard hairs, Wavy wool hairs and long tactile hairs

Question 4

How does hair develop?

Answer 4

Ectodermal bud grows into a mesenchyme, the bud differentiates and a developed hair follicle forms

Question 5

What are Guard and Wool hairs like in dogs and cats?

Answer 5

several hairs with a single follicle opening, one guard hair with several secondary wool hairs

Question 6

What are some examples of guard hairs?

Answer 6

Manes in horses, spines of hedgehogs, beards of goats

Question 7

What are the 3 growth stages for hair?

Answer 7

Anagen, Catagen, Telogen

Question 8

What occurs in anagen?

Answer 8

It is the growing phase, new keratin is pushed upwards

Question 9

What occurs during Catagen?

Answer 9

It is the transition phase, growth slows and the follicle shrinks

Question 10

What occurs during Telogen?

Answer 10

Telogen is the resting phase, Growths stops and the hair breaks free and is shed

Question 11

What are 7 functions of hair?

Answer 11

Cover sensitive structures, direct water, insulation, protection, camouflage

Question 12

How many epidermal layers do birds have?

Answer 12

2, stratum germinativum and stratum corneum

Question 13

What are the 3 glands birds have?

Answer 13

Uropygial gland, Aural gland and the Vent gland

Question 14

What are the 4 parts that make up the main structure of a feather?

Answer 14

Main shaft (rachis), Vanes either side, barbs with interlocking barbules and the base of the quill (calamus)

Question 15

What are contour feathers?

Answer 15

form the main surface of a bird, streamline and waterproof- can be primary or secondary

Question 16

What are down feathers?

Answer 16

they have a loose structure that interlocks and traps air for an insulation function

Question 17

What are bristle feathers?

Answer 17

Simple feathers, lack barb branches and have a sensory and protective function

Question 18

What are filoplumes?

Answer 18

hairlike feathers with a few soft barbs, can have a sensory function

Question 19

What is the function of the preen gland?

Answer 19

to waterproof the feathers by distributing preen oil

Question 20

What is the function of powder down feathers?

Answer 20

more prevalent in birds without a preen gland, produce fine waxy keratin powder

Question 21

How many layers does the reptile epidermis have?

Answer 21

3, germinativum, intermedium and corneum

Question 22

What are osteoderms?

Answer 22

bony plates in the dermis

Question 23

What are some special considerations in reptiles?

Answer 23

Thick keratinised scales reduce skin sensation, and they have cutaneous appendages with different functions

Question 24

What is Ecdysis?

Answer 24

Skin shedding, controlled by the thyroid gland- makes skin more permeable and susceptible to underlying disease

Question 25

What is Dysedysis?

Answer 25

an abnormal pattern of shedding

Question 26

Where are fish scales dermally derived from?

Answer 26

The mesoderm

Question 27

Extra notes on fish?

Answer 27

They have little keratinisation/ corneocytes so their skin is more permeable than other species

Question 28

What is the name of guard hairs in sheep?

Answer 28

Kemp Hairs

Question 29

Where are sebaceous glands found and why?

Answer 29

Attached to the hair follicle, because they produce an oily secretion that enters the hair

Question 30

Where do hair feathers and scales develop from?

Answer 30

Epidermis interacting with underlying mesenchymal tissue

Question 31

What controls Ecydysis?

Answer 31

The thyroid gland

Question 32

What type of feathers contain a core of vascular dermis?

Answer 32

Developing feathers

Question 33

What gland regulates shedding?

Answer 33

Pineal gland