The Common Integument Flashcards

Lect 3 Week 1 Basu

1
Q

What is the common integument?

A

the outer barrier of the organism

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2
Q

What does the common integument reflect?

A

the health of the animal

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3
Q

What is the common integument often affected by?

A

underlying diseases

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4
Q

What are the components of the common integument?

A

The subcutis and the cutis

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5
Q

What is the cutis made up of?

A

The dermis and the epidermis

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6
Q

What is the subcutis also known as?

A

Hypodermis or superficial fascia or subcutaneous tissue

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7
Q

What is the subcutis?

A

the piece of tissue that is beneath the skin

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8
Q

Give 5 examples of modified skin structures which fall under the common integument:

A

hair follicles + hairs
Skin glands, incl. mammary glands
foot pads
nails/claws/hooves
Horns + antlers

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9
Q

Describe what the subcutis is:

A

loose connective tissue between the skin and the muscle fascia

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10
Q

What component of the skin contains white fat?

A

the subcutis

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11
Q

What is white fat also known as in terms of tissue?

A

adipose tissue

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12
Q

Give three uses and benefits of adipose tissue:

A

Insulation, energy source, padding/protection (e.g. footpads)

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13
Q

The texture of the subcutis is dependent on what?

A

on water content
DRIER = STIFFER

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14
Q

What causes folds in the subcutis?

A

regional variations in fat and thickness of subcutaneous tissues

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15
Q

Why is the subcutaneous space important?

A

subcutaneous injection site
and is also a source of breed variation in dogs

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16
Q

What does the subcutis ‘sit on’, what is it attached to?

A

underlying cutaneous muslce

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17
Q

What is cutaneous muscle?

A

‘flat muscle sheets’
Thin, interrupted sheets spread over the body in the subcutis

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18
Q

What provides means for active movement of the skin?

A

muscle

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19
Q

Why is active movement of the skin useful?

A

e.g. horses use it as a diagnostic tool to shift flies

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20
Q

What is the cutaneous muscle called that is found over the neck and face?

A

platysma

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21
Q

What is the cutaneous muscle found over the frontal bone of the skull?

A

Frontalis

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22
Q

In which animal is the frontalis absent?

A

horses

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23
Q

What is the cutaneous trunci?

A

Covers the lateral sides of the trunk (torso) AND DORSALLY IN CATS to the tail

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24
Q

Describe the location of the cutaneous colli?

A

from sternum. spreads up neck

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25
Q

In what animal is the cutaneous colli best developed in?

A

horses

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26
Q

Name 6 cutaneous muscles:

A

platysma, frontalis, cutaneous trunci, cutaneous colli, cutaneous omobrachialis (continuation of trunci), preputial muscles

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27
Q

Describe the location of the cutaneous omobrachialis:

A

continuation of the cutaneous trunci over the shoulder and arm (ruminants and horses)

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28
Q

Describe the location of the preputial muscles:

A

connecting ventral midline to prepuce (carnivores, ruminants, pigs)

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29
Q

How is the dermis attached to the epidermis?

A

via interlocking papillae and ridges

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30
Q

What can adhesion (between the dermis and epidermis) be disrupted by?

A

repeated mechanical stress e.g. a blister

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31
Q

What is the dermis primarily composed of?

A

Connective tissue

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32
Q

What is the connective tissue composed of and what property does this give the skin?

A

composed of collagen (types I & II) and elastin = makes skin tough and stretchy

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33
Q

Describe quantity of cells the dermis has?

A

has few cells

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34
Q

What two regions does the dermis have?

A

a superficial papillary region & a deeper reticular region

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35
Q

What are papillae?

A

finger like projections, like interlaced fingers locking them together JOINING the dermis and the epidermis

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36
Q

Why are the papillae and ridges interlocking?

A

If they were flat then the dermis and epidermis would rub together easily and be easier to peel off

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37
Q

What is the superficial papillary region?

A

where the actual ‘finger-like’ projections are, the papillae

38
Q

What is the deeper reticular region?

A

deeper, under the papillary dermis

39
Q

How are the collagen fibres orientated?

A

in a particular way known as tension lines or Langer’s lines

40
Q

Why are tension lines important to be aware of?

A

when making an incision, you do not want to make an incision across the lines of tension, you would want to make it ALONG the lines of tension

41
Q

Explain why you wouldn’t want to make an incision across the lines of tension?

A

much harder to bring wound back together as the lines of tension would pull the wound apart

42
Q

Name 7 components of the dermis:

A

blood vessels, lymphatic vessels, nerves, sensory receptors e.g. Pacinian corpuscule, hair follicles, arrector pili muscles, sebaceous + sweat glands

43
Q

Which layer is the most superficial layer of the skin?

A

the epidermis

44
Q

describe the quantity of the cells in the epidermis:

A

rich in cells

45
Q

what does the epidermis lack?

A

nerves and blood vessels

46
Q

what kind of epithelium is the epidermis?

A

stratified squamous epithelium

47
Q

How many layers make up the epidermis?

A

4 or 5 layers

48
Q

How do we name a stratified epithelium?

A

Named after the most superficial layer/most visible layer

49
Q

Give the meaning behind the name stratum basale:

A

right next to the basement membrane

50
Q

What are the 5 layers of a stratified squamous epithelium?

A

Stratum basale (near BM)
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum (most superficial)

51
Q

What are keratinocytes?

A

skin cells

52
Q

Where are keratinocytes produced?

A

stratum basale - by mitotic cell division

53
Q

what is the duration of the complete cycle of keratinocytes?

A

20-30 days

54
Q

Briefly describe the complete cycle of the keratinocytes:

A

they move to the surface of the skin (produced in stratum basale, near BM remember)
Differentiating (changing) as they go before eventually sloughing off (falling off)

55
Q

What does the duration of the complete cycle of cell moving from stratum basale to skin surface depend on?

A

external circumstances: temperature
internal circumstances: age, hormonal status

56
Q

Describe what happens in the stratum basale and where it is found?

A

Attachment to the dermis, most closely spatially related to the dermis (basement membrane)
and it is the site where mitosis of keratinocytes occurs

57
Q

What happens in the stratum granulosum?

A

The keratinocytes are synthesising the protein/keratin granules which are needed for keratinisation.

58
Q

what is keratinisation?

A

the process of turning keratinocytes INTO corneocytes

59
Q

Tell me about the stratum lucidum:

A

very thin layer, sometimes it is there and other times it isn’t

60
Q

Describe the stratum corneum:

A

thick (depends on where you are in the body) waterproof cell membrane
dead cells (no organelles or nuclei)
fewer cell-cell attachments so can slough off
all of their proteins inside have been replaced by keratin which essentially suffocates and kills the cell

61
Q

Describe the varying thickness of the layers, especially the stratum corneum:

A

different layers can be different thicknesses in different parts of the body e.g. S.corneum is thicker at footpad
and it is especially the stratum corneum because this layer has direct contact with the external environment

62
Q

What are melanocytes and where are they found?

A

they are pigment cells and are found in the stratum basale and they protect against sun radiation

63
Q

What 4 cells are found in the epidermis?

A

keratinocytes, corneocytes, melanocytes, langerhans (immune) cells

64
Q

What do melanocytes produce?

A

melanin pigment

65
Q

What do melanocytes do with the melanin pigment?

A

distribute it to other cells - pass to keratinocytes via cellular processes

66
Q

What is the basement membrane (BM) sometimes called?

A

The basal lamina

67
Q

why don’t the melanocytes cells found in the most superficial layer of the epidermis take up stain very well?

A

because the nuclei have died, fewer proteins so don’t take up dye

68
Q

What are Langerhans cells also known as?

A

epidermal macrophages

69
Q

What are Langerhans cells?

A

antigen-presenting cells with cytoplasmic processes

70
Q

What other cells - apart from melanocytes also appear as poorly histologically stained cells?

A

Langerhans cells

71
Q

What do epithelia cells rely on for nutrients?

A

diffusion

72
Q

the epidermis has no…

A

BLOOD VESSLES (no blood supply)

73
Q

The dermis is very well…

A

vascularised

74
Q

meaning of vascularised?

A

lots of blood vessels

75
Q

how are the blood vessels in the dermis arranged?

A

into three plexuses

76
Q

what is a plexus?

A

a network - a mesh type of arrangement of blood vessels

77
Q

Describe the blood supply to the skin in three different points:

A
  • Cutaneous arteries (and veins) leave the subcutaneous plexus and pierce into the dermis
  • Form a deep network of vessels: reticular vascular plexus
  • Arterioles and venules reach the papillary dermis: Superficial papillary plexus
78
Q

What are the three plexuses that the dermis is contains?

A

Subcutaneous plexus
Reticular vascular plexus
Superficial papillary plexus

79
Q

Which plexus do the capillaries branch off of?

A

Off of the superficial papillary plexus

80
Q

How can we control the blood supply to the skin?

A

The walls of the arteries can dilate or constrict in order to increase/reduce blood supply

81
Q

What does this mean ‘Dermis and the subcutis are well-innervated’

A

That the dermis and the subcutis have a good supply of nerves

82
Q

What two types of nerves do the dermis and subcutis have?

A

Sensory and autonomic

83
Q

What do the autonomic nerves do?

A

regulate bodily functions e.g. temperature

84
Q

What 3 things do the autonomic nerves within the dermis supply?

A

sweat glands, arrector pili muscles, blood vessels

85
Q

Sensory nerves can terminate in free nerve endings, what three different types are they?

A

pressure, heat and pain

86
Q

Other sensory nerves terminate in what else? (STATE 2)

A

Corpuscles or hair follicle receptors

87
Q

What are corpuscles?

A

encapsulated nerve endings

88
Q

Which type of sensory neurone are very sensitive pressure sensors?

A

the sensory nerves that terminate in corpuscles or hair follicle receptors

89
Q

How do adipocytes appear under a microscope?

A

they appear as vacant cells with the nucleus pushed to the side - the nucleus is found at the periphery

90
Q

What layer of the integument is the ‘quick’?

A

the dermis

91
Q

Name the 11 components of the foot of the horse:

A

The toe
Quarter
Heel
Bar
Apex of the frog
Central sulcus
Lateral/medial sulcus
Bulb
Sole
White line
Hoof wall

92
Q
A