PBL 1 Flashcards
1
Q
What are the three layers of skin?
A
Epidermis, Dermis, Subcutis
2
Q
Where are the epidermal cells found?
A
On top of the dermis and subcutis
3
Q
What is the thin layer of extracellular proteins on the bottom called?
A
Basement membrane
4
Q
What comes after the Basement membrane?
A
Stratum basale
5
Q
What is the stratum basale?
A
a thin layer of mitotically active cells
6
Q
What type of junction connects the stratum basale to the basement membrane?
A
Hemidesmosomes
7
Q
What are hemidesmosomes (desmosomes)?
A
strong junctions
8
Q
What comes on top of the stratum basale?
A
stratum spinosum
9
Q
What is the stratum spinosum?
A
A layer of keratinocytes
10
Q
What are keratinocytes?
A
keratin producing cells
11
Q
what are the functions of keratin?
A
Waterproofing skin
12
Q
What holds the stratum spinosum (keratinocytes) together?
A
Desmosomes
13
Q
what is on top of the stratum spinosum?
A
Stratum granulosum
14
Q
What happens in the stratum granulosum?
A
Cells become flattened and are starting to lose nuclei and cytoplasm
15
Q
What is the top layer of the epidermis?
A
Stratum corneum
16
Q
What is the stratum corneum?
A
Large plate - like envelopes filled with keratin and are all linked together. It also contains some lipids
17
Q
What are the layers of the epidermis?
A
Basement membrane, Stratum basale, Stratum spinosum, Stratum granulosum and the Stratum corneum.
18
Q
what happens as cells move up the epidermis?
A
They become keratinised and begin to die as they can’t get enough nutrients
19
Q
Is the epidermis vascular or avascular?
A
Avascular
20
Q
How many layers of keratin are there?
A
20-30 layers
21
Q
How does the epidermis get its nutrients?
A
Supplied by the dermis
22
Q
What are the layers of the dermis?
A
The papillary and the reticular layer
23
Q
Where is the papillary layer?
A
The upper portion of the epidermis
24
Q
What is in the papillary layer?
A
Connective tissue
25
What is connective tissue?
Tissue that connects, supports, binds or separates other tissues or organs
26
Where is the reticular layer found?
The lower portion of the dermis
27
What is the reticular layer made of?
Highly dense connective tissue
28
What is the connective tissue in the reticular layer made up of?
Collagen type 1 and elastin fibers
29
What property does collagen give the skin?
Strength
30
What property does elastin give the skin?
Stretchiness
31
What are some additional feature of the dermis?
Blood vessels, Glands, Hair follicles, receptors and muscles.
32
Where is the subcutis?
Below the dermis and the epidermis. It is the lowest layer of the skin.
33
What does the subcutis contain?
Cells such as macrophages and fat cells and a network of protein fibers.
34
What are some functions of skin?
Protection - the skin forms a barrier
Thermoregulation - 80% of body heat is lost through the skin
Cutaneous sensation - including touch and pressure
Excretion - metabolic waste products can be released in the sweat
Absorption - lipid - soluble substances enter the body via the skin
Vit. D synthesis - starts in the skin triggered by uv light
35
Where are keratinocytes found?
In the epidermis - Aprox. 90% of epidermal cells are keratinocytes
36
What is keratin?
A tough fibrous protein
37
What else (apart from keratin) do keratinocytes produce?
Lamellar granules
38
What is the function of Lamellar granules?
To help waterproof the skin
39
Where are melanocytes found?
In the epidermis - Aprox. 8% of epidermal cells are melanocytes
40
What do melanocytes produce?
Melanin granules
41
What is the function of melanin?
To absorb UV radiation so protects the skin from sun damage
| It is also partly responsible for skin colour
42
What are Langerhans cells?
They are part of the immune system that originate in the bone marrow and move to the epidermis
43
What are the functions of Langerhans cells?
To recognise foreign microbes and engulf them.
| They can then present antigens to the immune system for further action.
44
Where are merkel cells found?
At the border of the epidermis
45
What feature do merkel cells possess?
Small dendrites that pass in between nearby keratinocytes
46
What is each merkel cell associated with?
A nerve ending called a merkel disc.
47
What does the combination of the merkel disc and the merkel cell function as?
A slow adapting touch receptor
48
What are the functions of fibroblasts?
To synthesise collagen, elastin and other extracellular components.
They also play a critical role in wound healing as a connective tissue.
49
Where can most of the lymphocytes in the skin be found?
The dermis
50
What are the functions of the lymphocytes?
Part of the immune response
| Carry out immuno-surveillance
51
What are the functions of mast cells?
Producing substances that cause inflammation e.g. histamine
52
How often does the skin renew?
Every 24hrs the skin sheds a layer of dead cells with the skin renewing completely every 28 days
53
How does renewal of the skin benefit the immune system?
It removes any potentially harmful pathogens from the surface of the skin
54
What happens as epidermal skin cells move up towards the surface of the epidermis?
They become keratinised - becoming flatter and gradually losing their nucleus and cytoplasm. They eventually die
55
What is another reason for the death of cells as they move towards the surface?
There is a lack of nutrients and oxygen they receive as they get higher up since the epidermis is receiving its nutrients from the dermis
56
What are the three overlapping stages of wound healing?
Inflammatory, proliferative, and remodelling
57
How are clots formed?
Fibrin and platelets combine to seal the wound from the external environment
58
What is the formation of the clot known as?
Haemostasis
59
What is inflammation triggered by?
The changes in microvasculature.
60
when does inflammation resolve?
after the neutrophils have finished clearing out the dead tissue
61
What are the main purposes of inflammation?
- expel any foreign bodies
- isolate the damaged area
- mobilise cells and molecules
- promote healing and tissue repair
62
What happens during the proliferative phase?
A lot of cell proliferation and the movement of epithelial cells to the injury site
63
How do fibroblasts move to the injury site?
Along fibrin threads
64
How do the fibroblasts contribute to clotting?
They secrete collagen which strengthens the clot
65
What is granulation tissue?
Delicate tissue that grows under the scab
66
How is the collagen deposited?
In a random arrangement
67
What is the change in type of collagen in the remodelling phase?
Type 3 to Type 1
68
What happens when the collagen changes?
The granulation tissue becomes scar tissue
69
What does the amount of scarring depend on?
The severity/depth of the wound.
70
Does scar tissue or normal tissue have more collagen fibers?
Scar tissue
71
Does scar tissue or normal tissue have reduced elasticity/stretchiness?
Scar tissue
72
Why are scars sometimes a lighter colour than normal tissue?
The way blood vessels arrange themselves
73
What is an incised wound?
Caused by a clean cut from a sharp edged object.
74
What treatment is required for an incised wound?
If the wound is deep, stitches may be required.
| They may be healed by primary intention as there is usually little or no tissue loss
75
What is a laceration?
These wounds occur when there is a blunt/ripping force
They may bleed less but there is likely to be more tissue damage
It is also more susceptible to infection due to the increased surface area
76
What treatment is required for an laceration?
These wounds require a lot of cleaning.
| Even if they are repaired very neatly by primary intention they often leave a lot of scarring
77
What is an abrasion (graze)?
A superficial wound in which the topmost layers of skin are scraped off. They can often contain lots of foreign particles meaning a high risk of infection
78
What is a contusion (bruise)?
A blunt blow can cause the rupture of capillaries below the skin
79
What is a puncture wound?
A deep wound with a small entry site
80
How should a puncture wound be treated?
It's often best to leave this type of wound open so that if there is any infection the wound can drain.
81
What is healing by primary intention?
- A clean, uninfected wound
- not much loss of tissue/cells
- The edges of the wound are approximated by sutures
82
What is healing by secondary intention?
- a wound with large tissue defects
- potentially infected
- the wound would not be approximated but is left open
83
At what age is a young person presumed to have capacity?
16
84
What are the laws in Scotland for 16/17 year olds who do not have capacity?
They are treated as an adult who doesn't have capacity and treatment may be given where required.
85
What is the law in Scotland to do with parents overriding consent?
In Scotland parents cannot override the competent consent of a young person to treatment that the doctor believes is in the patients best interests
86
What is the law in Scotland to do with parents authorising treatment a young person has refused?
Parents cannot authorise treatment that a competent young person has refused
