The Common Integument Flashcards
Lect 3 Week 1 Basu
1
Q
What is the common integument?
A
the outer barrier of the organism
2
Q
What does the common integument reflect?
A
the health of the animal
3
Q
What is the common integument often affected by?
A
underlying diseases
4
Q
What are the components of the common integument?
A
The subcutis and the cutis
5
Q
What is the cutis made up of?
A
The dermis and the epidermis
6
Q
What is the subcutis also known as?
A
Hypodermis or superficial fascia or subcutaneous tissue
7
Q
What is the subcutis?
A
the piece of tissue that is beneath the skin
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
9
Q
Describe what the subcutis is:
A
loose connective tissue between the skin and the muscle fascia
10
Q
What component of the skin contains white fat?
A
the subcutis
11
Q
What is white fat also known as in terms of tissue?
A
adipose tissue
12
Q
Give three uses and benefits of adipose tissue:
A
Insulation, energy source, padding/protection (e.g. footpads)
13
Q
The texture of the subcutis is dependent on what?
A
on water content
DRIER = STIFFER
14
Q
What causes folds in the subcutis?
A
regional variations in fat and thickness of subcutaneous tissues
15
Q
Why is the subcutaneous space important?
A
subcutaneous injection site
and is also a source of breed variation in dogs
16
Q
What does the subcutis ‘sit on’, what is it attached to?
A
underlying cutaneous muslce
17
Q
What is cutaneous muscle?
A
‘flat muscle sheets’
Thin, interrupted sheets spread over the body in the subcutis
18
Q
What provides means for active movement of the skin?
A
muscle
19
Q
Why is active movement of the skin useful?
A
e.g. horses use it as a diagnostic tool to shift flies
20
Q
What is the cutaneous muscle called that is found over the neck and face?
A
platysma
21
Q
What is the cutaneous muscle found over the frontal bone of the skull?
A
Frontalis
22
Q
In which animal is the frontalis absent?
A
horses
23
Q
What is the cutaneous trunci?
A
Covers the lateral sides of the trunk (torso) AND DORSALLY IN CATS to the tail
24
Q
Describe the location of the cutaneous colli?
A
from sternum. spreads up neck
25
In what animal is the cutaneous colli best developed in?
horses
26
Name 6 cutaneous muscles:
platysma, frontalis, cutaneous trunci, cutaneous colli, cutaneous omobrachialis (continuation of trunci), preputial muscles
27
Describe the location of the cutaneous omobrachialis:
continuation of the cutaneous trunci over the shoulder and arm (ruminants and horses)
28
Describe the location of the preputial muscles:
connecting ventral midline to prepuce (carnivores, ruminants, pigs)
29
How is the dermis attached to the epidermis?
via interlocking papillae and ridges
30
What can adhesion (between the dermis and epidermis) be disrupted by?
repeated mechanical stress e.g. a blister
31
What is the dermis primarily composed of?
Connective tissue
32
What is the connective tissue composed of and what property does this give the skin?
composed of collagen (types I & II) and elastin = makes skin tough and stretchy
33
Describe quantity of cells the dermis has?
has few cells
34
What two regions does the dermis have?
a superficial papillary region & a deeper reticular region
35
What are papillae?
finger like projections, like interlaced fingers locking them together JOINING the dermis and the epidermis
36
Why are the papillae and ridges interlocking?
If they were flat then the dermis and epidermis would rub together easily and be easier to peel off
37
What is the superficial papillary region?
where the actual 'finger-like' projections are, the papillae
38
What is the deeper reticular region?
deeper, under the papillary dermis
39
How are the collagen fibres orientated?
in a particular way known as tension lines or Langer's lines
40
Why are tension lines important to be aware of?
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
Explain why you wouldn't want to make an incision across the lines of tension?
much harder to bring wound back together as the lines of tension would pull the wound apart
42
Name 7 components of the dermis:
blood vessels, lymphatic vessels, nerves, sensory receptors e.g. Pacinian corpuscule, hair follicles, arrector pili muscles, sebaceous + sweat glands
43
Which layer is the most superficial layer of the skin?
the epidermis
44
describe the quantity of the cells in the epidermis:
rich in cells
45
what does the epidermis lack?
nerves and blood vessels
46
what kind of epithelium is the epidermis?
stratified squamous epithelium
47
How many layers make up the epidermis?
4 or 5 layers
48
How do we name a stratified epithelium?
Named after the most superficial layer/most visible layer
49
Give the meaning behind the name stratum basale:
right next to the basement membrane
50
What are the 5 layers of a stratified squamous epithelium?
Stratum basale (near BM)
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum (most superficial)
51
What are keratinocytes?
skin cells
52
Where are keratinocytes produced?
stratum basale - by mitotic cell division
53
what is the duration of the complete cycle of keratinocytes?
20-30 days
54
Briefly describe the complete cycle of the keratinocytes:
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
What does the duration of the complete cycle of cell moving from stratum basale to skin surface depend on?
external circumstances: temperature
internal circumstances: age, hormonal status
56
Describe what happens in the stratum basale and where it is found?
Attachment to the dermis, most closely spatially related to the dermis (basement membrane)
and it is the site where mitosis of keratinocytes occurs
57
What happens in the stratum granulosum?
The keratinocytes are synthesising the protein/keratin granules which are needed for keratinisation.
58
what is keratinisation?
the process of turning keratinocytes INTO corneocytes
59
Tell me about the stratum lucidum:
very thin layer, sometimes it is there and other times it isn't
60
Describe the stratum corneum:
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
Describe the varying thickness of the layers, especially the stratum corneum:
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
What are melanocytes and where are they found?
they are pigment cells and are found in the stratum basale and they protect against sun radiation
63
What 4 cells are found in the epidermis?
keratinocytes, corneocytes, melanocytes, langerhans (immune) cells
64
What do melanocytes produce?
melanin pigment
65
What do melanocytes do with the melanin pigment?
distribute it to other cells - pass to keratinocytes via cellular processes
66
What is the basement membrane (BM) sometimes called?
The basal lamina
67
why don't the melanocytes cells found in the most superficial layer of the epidermis take up stain very well?
because the nuclei have died, fewer proteins so don't take up dye
68
What are Langerhans cells also known as?
epidermal macrophages
69
What are Langerhans cells?
antigen-presenting cells with cytoplasmic processes
70
What other cells - apart from melanocytes also appear as poorly histologically stained cells?
Langerhans cells
71
What do epithelia cells rely on for nutrients?
diffusion
72
the epidermis has no...
BLOOD VESSLES (no blood supply)
73
The dermis is very well...
vascularised
74
meaning of vascularised?
lots of blood vessels
75
how are the blood vessels in the dermis arranged?
into three plexuses
76
what is a plexus?
a network - a mesh type of arrangement of blood vessels
77
Describe the blood supply to the skin in three different points:
- 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
What are the three plexuses that the dermis is contains?
Subcutaneous plexus
Reticular vascular plexus
Superficial papillary plexus
79
Which plexus do the capillaries branch off of?
Off of the superficial papillary plexus
80
How can we control the blood supply to the skin?
The walls of the arteries can dilate or constrict in order to increase/reduce blood supply
81
What does this mean 'Dermis and the subcutis are well-innervated'
That the dermis and the subcutis have a good supply of nerves
82
What two types of nerves do the dermis and subcutis have?
Sensory and autonomic
83
What do the autonomic nerves do?
regulate bodily functions e.g. temperature
84
What 3 things do the autonomic nerves within the dermis supply?
sweat glands, arrector pili muscles, blood vessels
85
Sensory nerves can terminate in free nerve endings, what three different types are they?
pressure, heat and pain
86
Other sensory nerves terminate in what else? (STATE 2)
Corpuscles or hair follicle receptors
87
What are corpuscles?
encapsulated nerve endings
88
Which type of sensory neurone are very sensitive pressure sensors?
the sensory nerves that terminate in corpuscles or hair follicle receptors
89
How do adipocytes appear under a microscope?
they appear as vacant cells with the nucleus pushed to the side - the nucleus is found at the periphery
90
What layer of the integument is the 'quick'?
the dermis
91
Name the 11 components of the foot of the horse:
The toe
Quarter
Heel
Bar
Apex of the frog
Central sulcus
Lateral/medial sulcus
Bulb
Sole
White line
Hoof wall
92
