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CRLS (CLB) > Integument 2; Hair, feathers, scales > Flashcards

Integument 2; Hair, feathers, scales Flashcards

1
Q

What do hairs, feathers and scales all develop from?

A

-Develop from the epidermis interacting with the underlying mesenchymal tissue

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2
Q

These are all homologous structures, what does this mean?

A

They share a common ancestry

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3
Q

What else develops through an epidermal-mesenchymal transition?

A

Teeth and mammary glands

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4
Q

How does a hair follicle develop?

A

1) Ectodermal bud grows into the mesenchymal beneath
2) There is then differentiation of the bud and sweat and sebaceous glands start form
3) The developed hair follicle is then formed with all the accessory structures

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5
Q

What are the 3 layers of a hair?

A

1) Cuticle
2) Cortex
3) Medulla

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6
Q

What is hair made of?

A

A long thin chain of keratin proteins

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7
Q

What is different about the structure of wool hairs?

A

They have no medulla

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8
Q

What are the 3 different types of hair?

A

1) Guard hairs (stiff and straight)
2) Wool hairs (fine and wavy)
3) Tactile hairs (sensory function)

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9
Q

What is the difference between a compound follicle and a single follicle?

A

Compound follicle - several hairs share a single follicle opening
Single follicle - one, primary guard hair

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10
Q

Describe a compound follicle

A
  • One primary guard hair, several secondary wool hairs.
  • Below the sebaceous gland, each hair has its own follicle and bulb
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11
Q

Which species have compound follicles?

A

Compound = dogs, cats, sheep, goats

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12
Q

Which have single follicles?

A

Single = horses, cattle, pigs, humans

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13
Q

What is the orientation of guard hairs?

A

They lie against the skin and run in tracts in the same direction

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14
Q

What features on horses are made of guard cells?

A

Mane, tail, fetlock tufts

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15
Q

What about on cattle and goats?

A
  • Long tail hairs on cattle
  • Beards on goats
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16
Q

What is unique about the structure of tactile hairs?

A
  • Reach deep into the subcutis
  • Surrounded by a venous sinus
  • There is a dermal sheath surrounding the follicle which contains nerve endings
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17
Q

What is the importance of this venous sinus?

A

When the hair vibrates, the liquid in the sinus moves and vibrations are amplified in the dermis.

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18
Q

What gland regulates the hair growth cycle?

A

Pineal gland

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19
Q

What factors affect shedding and hair growth?

A
  • Seasonal (shedding peaks in spring and autumn)
  • Affected by day length, temp and nutrition
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20
Q

What phase of the growth cycle are most hairs in?

A

Anagen phase

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21
Q

What happens in each of the 3 phases of hair growth?

A

1) Anagan = growing phase
2) Catagen = transition phase, growth slows
3) Telogen = resting phase, growing stops

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22
Q

What type of diseases can cause hair loss?

A

Endocrine diseases

23
Q

In the anagen phase, which cells produce the hair and what cells make up the hair shaft?

A
  • Epidermal stem cells divide to produce the hair
  • Hair shaft made of dead keratinocytes
24
Q

How is the hair anchored to the follicle in the anagen phase?

A

Tightly anchored by root sheaths

25
Q

How is apoptosis used in the catagen phase?

A

Programmed cell death at the base of the follicle to make the follicle shorten - follicle is shortest in telogen phase.

26
Q

How does the hair provide a protective function?

A
  • Tough keratin hairs cover sensitive surfaces
  • Can cover sensory organs such as the eye
27
Q

How do hairs aid with water resistance?

A
  • Oily sebaceous glands open into follicles
  • Guard hairs run unidirectional to encourage water flow off
28
Q

How do hairs aid with thermoregulation?

A
  • Wool hairs trap air
  • Arrector pili and guard hairs
  • Some sweat glands open into follicle
29
Q

How do hairs aid with communication and camouflage?

A
  • Melanin (colour)
  • Glands open into follicle
30
Q

What 2 layers are present in the epidermis in birds?

A
  • Stratum germinativum
  • Stratum corneum
31
Q

What 3 glands are present in bird skin?

A

1) Uropygial gland (preen gland)
2) Aural gland
3) Vent gland

32
Q

What feathers should be avoided when wing clipping?

A

Blood feathers

33
Q

Describe the structure of a feather

A
  • Rachis runs down the middle
  • Vane on either edge
  • Barbs either side of the rachis
  • Calamus at the base of the quill
34
Q

What are the 6 different types of feather?

A

1) Contour feathers
2) Hyopenna
3) Down feathers
4) Semi-plumers
5) Filoplumes

35
Q

What type of feather helps with water waterproofing and flight?

A

Contour feathers

36
Q

What type of feather is good for insulation?

A

Down feathers

37
Q

What are powder down feathers?

A

Down feathers that produces fine, waxy keratin powder (helps to keep feathers clean) + waterproofing
Absence of powder can indicate disease

38
Q

What are the 3 layers of the epidermis in reptiles?

A
  • Stratum germinatium
  • Stratum intermedium
  • Stratum corneum
39
Q

What do reptiles (and some amphibians) have that other animals do not?

A

Osteoderms (bony plates in the dermis)

40
Q

What leads to reduced skin sensation in reptiles?

A

Thick keratinised cells

41
Q

Which gland controls ecdysis (skin shedding)?

A

Thyroid gland

42
Q

What are some specialized cutaneous features of reptiles?

A
  • Clear spectacle scale over eyes
  • Belly scales aid locomotion in snakes
  • Heat sensitive pits aid prey detection
43
Q

What is dysecdysis?

A

Improper shedding = old skin can dehydrate and shrink to cut off circulation

44
Q

What happens to the spectacle scale during shedding?

A
  • Goes opaque
45
Q

What are the 2 types of skin glands?

A

1) Sebaceous glands
2) Sweat glands

46
Q

Describe the structure and location of sweat glands

A

They are coiled, tubular glands
They sit within the dermis but are derived from the epidermis

47
Q

What are the 2 different types of sweat glands?

A
  • Eccrine
  • Apocrine
48
Q

What do sebaceous glands look like?

A

Lobed, acinar structure

49
Q

What do sebaceous glands produce?

A

Produces fatty, oily sebum
- Moisturises and waterproofs hair and skin
- Antimicrobial function
- Pheromones released

50
Q

What do apocrine sweat glands produce?

A

Discharge albuminous sweat (protein rich)
- Reacts with bacteria to produce odour

51
Q

Where are apocrine sweat glands found?

A

Found in haired skin

52
Q

What do eccrine sweat glands produce?

A

Discharge watery sweat onto the skin surface

53
Q

Where are eccrine sweat glands found?

A

Found in particular areas of naked skin (e.g., foot pads/ nasolabial plate of cattle)

CRLS (CLB) (14 decks)

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