BMS08-1007 Skin Flashcards
1
Q
What is the epithelial layer called?
A
The epidermis
2
Q
What does the epidermis rest on?
A
The dermis
3
Q
What is the top of the dermis called?
A
Dermal papillae
4
Q
What is the bottom of the epidermis called?
A
Epidermal ridges
5
Q
Name the 4 functions of the skin
A
Protection
Prevent dryness
Sensation
Thermoregulation
6
Q
Which part of the skin is responsible for thermoregulation?
A
Dermis and hypodermis
7
Q
What is responsible for sensation?
A
Dermis
8
Q
What is responsible for stopping dryness?
A
The waterproof cornified layer in the epidermis
9
Q
What element of the skin is responsible for protection?
A
Epidermis
10
Q
What does the skin need to be protected from?
A
Chemicals Heat Cuts Infection UV
11
Q
Which vitamin does the skin make?
A
D
12
Q
How is the skin involved in metabolism?
A
Fat deposits in the hypodermis can be used as an energy store
13
Q
What can the skin excrete small amounts of?
A
Urea, uric acid and ammonia in sweat
14
Q
What’s the difference between thick and thin skin?
A
Cornified layer is larger in thick skin and it doesn’t have hair follicles
15
Q
What is body skin called?
A
Vellus
16
Q
What is scalp skin called?
A
Terminal
17
Q
How does skin and scalp skin differ?
A
The body is sparse and fine while the scalp has many closely packed thick hair
18
Q
What is the main cell type in the epidermis?
A
Stratified squamous keratinizing epithelium (keratinocytes)
19
Q
How are keratin proteins organised in the epidermis?
A
In bundles of filaments
20
Q
Where do the bundles converge?
A
Desmosomes
21
Q
What is a desmosome?
A
Structure linking adjacent cells
22
Q
What is pemphigus?
A
Blistering disease due to antibodies attacking desmosomes
23
Q
What cell type forms the basal layer?
A
Cuboidal or columnar epithelial cells
24
Q
What occurs at the basal layer?
A
Cell division due to the presence of stem cells
25
What do the prickle cells do?
Enlarge and make lots of keratin
26
What are there lots of in the prickle cell layer?
Desmosomes
27
What do the cells in the granular layer synthesise?
Profilaggrin
28
How are the granular and cornified layers linked?
Profilaggrin is cleaved to filaggrin in the cornified layer
29
What does filaggrin do?
Combine slots of keratin filaments together to help cell flattening
30
Describe the appearance of the granular layer?
Flattened cells
| Keratohyaline granules
31
What do keratohyaline granules do?
Involved in keratinization
32
What is the appearance of the cornified layer?
Very flattened cells
33
What happens in keratins in the cornified layer?
Disulphide bonds cross link them using cysteine
34
Why do keratin filaments get more packed together in the cornified layer?
Cells die and loose their organelles
35
How is the cornfiied and prickle layer linked?
Involucrin proteins that are made in the prickle layer get cross linked to form a cornified envelope
36
What are involucrins?
Precursors of the certified envelope
37
What is cornification?
When keratinocytes are converted into dead corneocytes
38
What forms the cornified envelope?
The cell membrane of corneocytes is replaced by ceramides which all link up
39
What are ceramides?
Waxy lipid molecule
40
What are lamellar bodies?
Secretory organelles between keratinised cells
41
What appears in the prickle cell layer?
Lamellar bodies
42
What are lamellar bodies made of?
Phospholipid sheets
43
What is the purpose of lamellar bodies?
Seals gaps between cells to make a water tight barrier
44
Which cell makes melanin?
Melanocytes
45
How do different skin colours arise?
The amount of melanocytes are similar but their activity varies
46
Which AA makes melanin?
Tyrosine
47
Where does melanin accumulate?
Malenosomes
48
How are melanosomes formed?
Bud off from melanocytes
49
What takes up melanosomes?
Keratinocytes
50
Tumors of melanocytes
Melanomas
51
How do epidermal cells arrange melanin?
As a cap over the nucleus
52
What is vitiligo?
Antibodies attack melanocytes
53
Where are Langerhans found and what is their function?
Upper prickle cell layer
| Immunological defence
54
Where are merkel cells found?
Basal layer
55
What is the role of merkel cells?
Associated with nerve endings, thought to be involved in sense perception
56
What are the 2 layers of the dermis?
Top is the papillary and the bottom if the reticular
57
What is the dermis?
Dense irregular connective tissue made of parallel bundles of collagen fibres
58
Is the dermis innervated?
Yes
59
How are the collagen fibres orientated in the dermis?
Along lines of cleavage
60
What is below the dermis?
Hypodermis
61
What regulates how much blood flows near the skins surface and how much flows in the dermal layer?
Arteriovenous shunts
62
In the skin which 2 vessels are used for thermoregulation?
Superficial subpapillary plexus and deep cutaneous plexus
63
Which elements are responsible for superficial and deep sensation, where are they and what kind of touch do they provide?
Deep: pacinian corpuscles in the hypodermis for coarse touch
Messners corpuscles in the dermis for light touch
64
What can be associated with merkel cells?
Free nerve endings
65
What do free nerve endings respond to?
Temperature, touch and pain
66
What type of connective tissue is the hypodermis?
Loose connective tissue
67
What does the hypodermis allow for?
Mobility of the skill
68
What type of cell is there lots of in the hypodermis?
Fat cells
69
What anchors the dermis to deep fascia?
Fibrous bands (bundles of collagen)
70
What are hair follicles associated to?
Errector pili muscles and sebaceous glands
71
How do hair follicles form?
As a down growth from the epidermis
72
Which part of the NS innervates the sweat glands?
Sympathetic
73
What's the difference between tubular and alveolar glands?
Alveolar have a sac like part that tubular glands don't as they remain tube shaped
74
Describe the shape of the secretory portion
Highly coiled
75
Where is the secretory portion found?
Between the dermis and hypodermis
76
What cells form the secretory portion of the gland?
Single layer of cuboidal cells ad myoepithelial cells
77
What does the secretory portion secrete?
Isotonic fluid
78
What cells form the excretory duct?
Double layer of the cuboidal cells
79
What does the excretory duct absorb and why?
NaCl to make hypotonic sweat
80
What's the difference between isotonic and hypotonic?
Hypotonic means the solution is less concentrated, isotonic means its the same concentration
81
Which parts of the excretory ducts are found where?
Straight bit is in the dermis and the coiled bit is in the epidermis
82
How is the epidermis organised?
Basal layer, prickle layer, granular layer, cornified layer and the epidermal ridges
83
How do apocrine sweat glands work?
Tip of the cell buds off forming a vesicle
84
Where are apocrine sweat glands found?
Genitalia
| Arm pits
85
What do apocrine and sebaceous glands discharge into?
Hair follicles
86
What is in apocrine vesicles?
The secretion, lipids and some cytoplasm
87
What where mammary glands originally?
Apocrine glands
88
Which part of hair follicles to sebaceous glands discharge into?
The upper third
89
What do seb. glands release?
Lipid rich sebum
90
What do seb. glands maintain?
Maintains oiliness of skin and hair
91
What is holocrine secretion?
When cells disintegrate to release the sebum
92
What type of tissue does the arr pili muscle insert into and which layer of the skin is this in?
Connective tissue sheath around the hair follicle in the papillary layer of the dermis
93
Which keratinocytes have a different differentiation pathway?
Hair bulb ones
94
How are cells organised in hairs?
Concentric rings
95
Describe the cell layers of the hairs?
```
Medulla
Cortex
Cuticle
Inner root sheath
Outer root sheath
```
96
Organise these layers into order of most keratinized; cortex, cuticle, medulla
Cuticle
Cortex
Medulla
97
Whats the role of the inner root sheath?
Provide space for the sebum to be discharged into
98
What does the outer root sheath do?
Has steam cells which can regenerate the epidermis
99
What is the outer root sheath continuous with?
Epidermis
100
What type of tissue forms the hair papilla?
Connective tissue
101
Why do we go bald?
If connective tissue in hair papilla is destroyed no hair will grow back it forms only once during development
102
How can you tell the difference between an active and dormant hair cells?
Dormant are shorter, when they are active they get longer again
103
What is the name of inactive hair?
Quiescent follicle
| Club hair
104
What gland are all hair follicles attached to?
Sebacious
