Skin (1) Epidermis Flashcards
What are the 4 primary tissues of the skin?
epithelium
connective tissue
muscle
nerve
What are epidermal cells called?
keratinocytes
Does the skin have itsown nerve an dblood supply?
YES
What is one of the first organs noticeable in patients?
skin
What are some pathological conditions associated with skin?
sunburn, acne, eczema, psoriasis, melanoma
What can the skin reveal about a patient?
Provides important external evidence of underlying systemic conditions: eg. liver disease, systemic sclerosis, mitral stenosis, urticaria
What are the 3 main layers of skin?
What is the role of the epidermis?
prevents water loss by evaporation
What is the function of the dermis?
- reduces risk of external injury
- maintains the epidermis by its blood flow
- permits body cooling
What are some general functions of the skin?
Immune surveillance
UV protection
Energy storage
sensory information
What layer of the skin prevents water loss by evaporation?
epidermis
Name skin layers A-C
What characterises the epidermis?
epithelium
Forms boundary between internal and external environments
What characterises the dermis?
connective tissue
- Gives structural strength
What characterises the hypodermis?
adipose tissue
anchors skin to underlying tissue
Name structures A-C
What layer of the skin is characterised by adipose tissue?
hypodermis
What layer of skin is characterised by connective tissue?
dermis
What is the outer layer of the skin?
epidermis
How many strata does the epidermis have?
5
What does strata mean?
sublayers
Define the epithelium - tissue morphology?
Epithelium = stratified squamous keratinising epithelium
How many basic types of epidermal cells are there?
4
What are the 4 basic types of epidermal cells?
- keratinocytes
- melanocytes
- langerhans cells
- Merkel cells
What is the most frequent type of epidermal cell in the epithelium?
keratinocytes
What is the role/characterise keratinocytes?
– Most frequent, contain keratin (contains sulphur), hard, resistance to abrasion.
– Extrude lipids – waterproofing.
– Constantly dividing – self regeneration protecting from trauma and other damage.
What do keratinocytes extrude?
lipids - waterproofing
Why do the keratinocytes constantly renew?
protecting from trauma and other damage.
What are arrows A-C pointing to? (epidermal cells)
What is the role of melanocytes?
PIGMENT FUNCTION
What is the role of langerhans cells?
immune surveillance
What is the role of Merkel cells?
touch receptors
What are the 5 layers of the epidermis?
- Str basale
- Str spinosum
- Str granulosum
- Str lucidum
- Str corneum
Are the layers of the epidermal layers sharply defined?
NO
Name layers A-E of the epidermis
Describe the tissue of the Stratum basale layer of the epidermis
Tall columnar cells interspersed with melanocytes and Merkel cells
What cells are found in the Stratum basale?
melanocytes and Merkel cells
How are cells bound to the basal membrane of in the epithelium?
hemidesmosomes
What direction do keratinocytes mature?
inside to surface
How would you describe the interface between the dermis and stratum basale?
irregular
How is there constant cell proliferation in the stratum basale?
undifferentiated stem cells
How would you describe the stratum spinosum?
spinous layer
What layer of the epidermis is the Str spinous located?
The stratum spinosum is a layer of the epidermis found between the stratum granulosum and stratum basale
How does the stratum spinosum form spines?
Created post-mortem:
Cells shrink but desmosome junctions
“create” spines
Their spiny appearance is due to shrinking of the microfilaments between desmosomes
What is the stratum spinosum composed of?
polyhedral keratinocytes
What is the stratum spinosum joined with?
desmosomes
How is the stratum spinosum involved in making keratin cells?
Preparative layer for keratinisation
What epidermal layers does the stratum granulosum lie in-between?
Above the Stratum spinosum and below the Stratum lucidum
What defines the stratum granulosum?
Presence of granules defines the layer
What granules in the stratum granulosum contain possible precursors of keratin?
Granules of keratohyalin (possible precursors of keratin)
Name epithelial layers A-D
What layer of the epithelium is shown here?
stratum granulosum
What 2 layers are difficult to distinguish?
Stratum lucidum & Stratum corneum
What layers are responsible for the conversion of keratohyalin to keratin?
Stratum lucidum & Stratum corneum
What give the Stratum lucidum & Stratum corneum strength?
disulphide linkages
Does the Stratum corneum have organelles?
NO
What binds cells together in the Stratum lucidum & Stratum corneum?
desmosomes
What is the turnover of Stratum lucidum & Stratum corneum?
15-30 day turnover
Name areas of the body with thick skin
palms of hands and soles of foot
Name areas of the body with thin skin
abdominal skin
Is this an image of thick of think skin?
Thick
Is this an image of thick of thin skin?
Thin
Which image is thick skin and which is thin skin?
left thin
right thick
Can skin thickness be dynamic?
YES
What layer of skin varies the most in epidermal thickness?
stratum corneum
(dermis also does)