Lecture 9: Skin Flashcards
What is the function of the skin?
Sensory Reception
Thermoregulation
Excretion
Protection
Vit D production
What are the 2 main layers of the skin
Epidermis: stratified keratinized squamous epithelium
Dermis: Deeper connective tissue with embedded structures + subcutaneous layer which houses areolar and adipose tissue
What are the main cell types that make up the epidermis?
- Keratinocytes - Most abundant and produce keratin
-
Melanocytes- produce melanin which absorbs UV and gives skin colour
-
Langerhans Cell- Immune response recognise foreign substance
- Tactile Epithelial Cell- touch sensation
-
Langerhans Cell- Immune response recognise foreign substance
What are the 5 layers of the epidermis?
- Stratum Basale
- Stratum spinosum
- Stratum Granulosum
- Stratum Lucidium
- Stratum Corneum
Identify all key features of the epidermis
What role does the stratum Basale play?
Single layer of Basal columnar or cuboidal cells on the basement membrane at the dermal-epidermal junction
Contains frequently mitotic stem cells which is responsible for the production of keratinocytes
What is the function of the stratum spinosum?
slightly flattened cuboidal or slightly flattened keratinocytes
PREKERATIN FILAMENTS
What is the function of stratum granulosum
3-5 layers of polygonal keratinocytes which undergo apoptosis
Contain lamellar granules for waterproofing!
What is the function of stratum lucidum
Translucent dead flattened cells
Densely packed keratin filaments which are not found in thin skin
What is the function of the stratum corneum
Cornified surface layer
no nucleus and are packet with keratin
How does the epidermis produce skin colour?
Melanocytes produce melanin which varies skin colour.
UV stimulates the production of melanin
Where is the dermis located?
Supporting CT on which epidermis sits and which binds to the subcutaneous tissue.
What are the epidermal appendages in the dermis?
hair follicles
hair
sweat glands
sebaceous glands
nails
mammary glands
ALSO HAS BLOOD VESSELS NERVES AND NERVE ENDINGS
What are the two main layers of the dermis?
Upper pappilary layer
Lower reticular layer
What are characteristics of the upper papillary layer?
Areolar CT
Meissner’s corpuscles, fine blood vessels and free nerve endings
What are characteristics of the lower reticular layer?
Dense irregular CT
LYMPH and collagen provides strength
What are the dermis cleavage lines?
Lines where dermal collagen fibres run.
Cuts perpendicular to cleavage lines may gape and take longer to heal
Cuts parallel to cleavage lines will take shorter to heal
Describe the dermal-epidermal junction
Irregular wave like pattern
Dermal papillae interdigitate with epidermal ridges (GAS EXCHANGE OCCUR HERE)
What are the 3 main parts of the hair
Hair bulb
hair root
hair shaft
What are the 3 layers of the hair
- Medulla
- Cortex
Cuticle
- Cortex
What makes up the hair follicle?
Internal root sheath
external root sheath
dermal root sheath
What is the muscle that can make a hair strand erect
Arrector Pilli: smooth muscle band
What is the function of sebaceous glands?
= Secretes sebum (oil)→ coats hair and skin and makes them waterproof
= more frequent of face, forehead and scalp
= located in dermis
What is the function of sweat glands and what are the main types?
- Sudoriferous glands.
- Two main types-
- Apocrine sweat glands- connected to hair follicle and produces body odour
- Eccrine sweat glands- Simple coiled tubular structure
function : THERMOREGULATION
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