Integument 2 Flashcards

Hair, feathers, scales and glands

1
Q

What does hair, feathers and scales all develop from?

A
  • all develop from epidermis interacting with underlying mesenchymal tissue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Hair, feathers, scales are homologous structures what does this mean?

A
  • they share a common ancestry
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How can hairs, feathers and scales come to be?

A
  1. two layers will come together
  2. then will then fold
  3. then secrete proteins which can interact and make individual structures
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How do teeth and mammary glands develop?

A
  • through an epidermal-mesenchymal interaction
  • a single evolution origin, modified to make all these different ectodermal organs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the stages of hair follicle development?

A
  1. ectodermal bud growing into mesenchyme
  2. differentiation of the bud and indications of glands = primitive hair follicle, sweat gland bud, sebaceous gland bud
  3. developed hair follicle with accessory structure = arrector pili muscle, sweat and sebaceous gland
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the structure of hair?

A
  • long thin chain of keratin protein
  • unique to mammals
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the hair typically composed of?

A
  • a central medulla
  • a thick cortex
  • an outer cuticle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

The structure of hair can vary and can be used to identify different species.
what is different about wool hair for example?

A
  • it has no medulla
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the 3 basic hair forms?

A
  • stiff straight guard hairs (topcoat)
  • fine wavey wool hairs (undercoat)
  • thick long tactile hairs (stiff and straight and project deeply into dermis) = sensory function
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What Animals can have a compound follicle be found in?

A
  • dogs
  • cats
  • sheep
  • goats
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a compound follicle?

A
  • several hairs share a single follicle opening
  • usually one primary (guard hair) and several secondary (wool) hairs
  • below sebaceous gland, each hair has its own follicle and bulb
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What animals have a single follicle?

A
  • horses
  • cattle
  • pigs
  • humans
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a single follicle?

A
  • one primary (guard) hair
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How do you describe the orientation of guard hairs?

A
  • generally lie against the skin and run in tracts of the same direction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why do guard hairs run in the same direction?

A
  • encourages water to run off skin in one direction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Name some species specific modifications of guard hairs:

A
  • mane, tail and fetlock tufts of horses
  • stiff, sparse bristles of pigs
  • long tail hairs of cattle
  • beard of goats
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Domestic sheep have fewer what hairs?

A
  • fewer guard (kemp) hairs
  • so fleece is almost exclusively wool hairs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Where are tactile hairs mostly found?
and where can cats also have these hairs?

A
  • mostly on face/head
  • cats can have tactile carpus hairs too
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How deep do tactile hairs reach?

A
  • reach deep into subcutis or even muscle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are tactile hairs surrounded by?

A
  • surrounded by a venous sinus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why are tactile hairs surrounded by a venous sinus?

A
  • blood wave amplifies the stimulation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Tactile hairs also have a dermal sheath surrounding the follicle what does this contain?

A
  • contains nerve endings
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Guard and wool hairs have a limited lifespan and are gradually shed - why do are hair cycles offset?

A
  • so healthy animals never totally loose their hair
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Lots of shedding is seasonal - when are the peaks?

A
  • spring and autumn
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What can shedding be regulated by?
- regulated by pineal gland - day length, temperature and nutrition
26
Why are domestic animals starting to shed all year round?
- we have changed their environment so it is at a constant temperature and nutrition is less variable meaning indicators for shedding are less obvious
27
What makes up the hair growth cycle and what can modify it?
- 3 phases with intrinsic rhythmicity - can be modified by hormones
28
In normal-haired animals what phase are most hairs in?
- anagen
29
Name the 3 phases of hair growth:
1. anagen 2. catagen 3. telogen
30
What is the anagen phase?
- growing phase - most follicles - duration is genetically determined - hair is tightly anchored in follicle by root sheaths
31
What is the catagen phase?
- short transition phase - growth slows - atrophy of follicle - involution (by apoptosis - programmed cell death) of inferior portion
32
What is the telogen phase?
- resting phase - growth stopped - hair eventually break free and can be shed due to shortening of follicle - duration varies between breeds - cycle starts over
33
Describe the process of active hair growth in anagen:
- there is a dermal papilla comprised of mesenchymal cells - epidermal stem cells divide to produce hair shaft and sheath - hair shaft is dead keratinocytes packed together
34
What can some atrophic diseases cause?
- miniaturisation of the follicle or arrest the cycle - such as endocrine diseases - endocrine alopecia
35
State the function of hair:
- protection - water resistance - thermoregulation/insulation - communication/camouflage - sensory function
36
How does hair protect?
- tough keratin hairs covering sensitive structures such as a tail covering genitalia
37
How does hair aid in water resistance?
- oily sebaceous glands opening into follicle - same direction tracts of guard hairs encourages water run off in one direction
38
How is hair involved in thermoregulation and insulation?
- wool hairs trap air - arrector pili and guard hairs - some sweat glands open into follicle
39
How is hair involved in communication or camouflage?
- melanin (colours) = derived from epidermis - arrector pili - glands opening into follicle
40
How are hairs involved in sensory function?
- tactile hairs
41
Feathers are unique to birds (dinosaurs) - What are they homologous to?
- homologous to hairs in mammals = keratin structure from epidermis = shared ancestor (and similar function)
42
Feathers first evolved in non-avian dinosaurs for what purposes?
- insulation - communication/display - later used for flight
43
What are the consequences of evolution for flight?
- reduced weight of everything such as bone and skin - skin is very thin and tears easily
44
Birds only have 2 epidermal layers what are they?
- stratum gerinativum (basale) - stratum corneum
45
Birds skin is essentially glandless, it only has three glands what are these?
- uropygial (preen) gland - aural gland - vent gland
46
Developing feathers contain a core - what is it?
- a core of vascular dermis = important difference from mammal hair
47
What may happen if a feather is plucked or broken out? and What should you never do to blood feathers?
- may bleed a lot - should not cut blood feathers when clipping
48
What is the name for the main shaft of a feather?
- rachis
49
Feathers have vanes either side which can be asymmetrical - what are they made up of?
- made up of barbs - with microscopic interlocking barbules
50
What is the base of the quill called?
- calamus
51
What is the structure of a contour feather?
- incudes flight feathers - asymmetric vanes for an aerofoil shape - interlocking barbules for a smooth streamlined, water proof surface
52
What are hyopenna (afterfeathers) associated with?
- contour feathers
53
What is the structure of down feathers?
- non-interlocking barbules trap air
54
What are semi-plumes?
- like down feathers, fluffy insulators
55
What is the structure and function of bristles?
- few barbs - sensory and protective
56
What are filoplumes?
- sensory - help with flight adjustment
57
Some birds have special powder down feathers what do these do?
- produce fine, waxy keratin powder - similar function to preen gland (cleaning and waterproofing) - often cause human allergies = pigeon fanciers lung
58
What birds have more abundant powder down feathers?
- bird species without a preen gland
59
What can be the fist sign of disease in birds?
- absence of feathers - e.g. psittacine beak and feather disease
60
The reptiles epidermis had 3 layers what are these?
1. stratum germinativum (basale) 2. stratum intermedium 3. stratum corneum
61
What are glands like in reptiles?
- few glands, restricted to certain areas of the body
62
Reptiles scales are homologous to what?
- hairs and feathers - shared ancestry = all are keratin structures from epidermis
63
Reptiles and amphibians can sometimes also have osteoderms - what are these?
- bony plates in the dermis - in tortoise, shell is formed from osteoderm fusion with ribs
64
Thick keratinised scales reduce what and what can this lead to?
- reduce skin sensations leading to a risk of thermal burns
65
Reptiles can have cutaneous appendages with special functions name some:
- clear spectacle scales over eyes - light-sensitive parietal eye - associated with pineal gland - scales and structures that ais in locomotion (snake belly scales, adhesive toe pads) - cloacal spurs aid in reproduction - heat sensitive pits for prey detection - crests, frills, horns, pouches, spines for display and defence
66
What is the scientific name for shedding?
- ecdysis
67
What is the role of shedding?
- replaces worn skin - either whole or bit-by-bit
68
What controls shedding?
- thyroid gland
69
What reptile eats shed skin?
- geckoes
70
What is the name for improper shedding?
- dysecdysis
71
What issues can dysecdysis cause?
- constriction of body parts
72
What can cause dysecdysis?
- inappropriate humidity/ not enough rough objects
73
Inappropriate shedding can be a sign of what?
- underlying disease or husbandry problems
74
Reptile skin is more permeable what does this lead to?
- more susceptible to infection, parasites and medication overdose
75
What happens if the clear spectacle over the eye goes opaque as it separates?
- can cause animal to he more aggressive
76
There are two basic skin glands and further sub-types what are these called?
- sebaceous glands - sweat glands * eccrine * apocrine (can sometimes open into hair follicle)
77
What are skin glands a modification of?
- the epidermis - even though they penetrate into the dermis
78
What are sebaceous glands associated with?
- hair follicles
79
What structure do sebaceous glands have?
- many lobed (acinar) structure
80
What do sebaceous glands produce?
- fatty/oily sebum (lanolin in sheep)
81
What does sebum aid in?
- moistures and waterproofs hair and skin - allows sweat to spread (thermoregulation) - antimicrobial function - pheromones or other scented compounds for communication
82
Some groups of sebaceous glands are enlarged and visible to the naked eye - what are these?
- horn glands - glands of infraorbital pouch
83
What are the two types of sweat glands?
- apocrine - eccrine
84
Describe apocrine sweat glands?
- discharge albuminous (protein-rich) sweat - into hair follicles - over most of body in domestic animals - react with bacteria to produce an individuals odour
85
Describe eccrine sweat glands:
- discharge more watery sweat - directly onto skin surface - generally found in certain areas (naked skin) - footpads of dogs - nasolabial plate of cattle
86
What do sweat glands look like?
- coiled and tubular