Structure and function of Skin Flashcards
What does integument or integumentary system refer to?
Refers to the skin, hair and nails
What is the largest and heaviest organ of the body?
Skin is the largest and heaviest organ of the body
What are the main function of skin?
1) Barrier against:
- Dehydration
- Infection
- Injury
- Solar radiation
2) Thermoregulation
3) Sensation
4) Repair
5) Vitamin D production
What are the 3 layers of skin?
- Epidermis
- Dermis
- Hypodermis
Where does the thickness of the epidermis vary?
Thickness varies around the body
What are the 4 main layers of the epidermis?
- Basal layer
- Stratum spinosum
- Stratum granulosum
- Stratum corneum
What does the basal layer contain?
Contain the stem cells of skin that constantly proliferate
What does the stratum spinosum have many of?
The cells have many desmosomes visible as spines between cells
What is the stratum granulosum?
1-4 layers of cells containing prominent granules
What does the stratum granulosum contain?
Contain lamellar bodies containing lipids
What do the cell of the stratum granulosum do?
The cells are differentiating to form the stratum corneum
What is the stratum corneum?
It is the outer protective layer of the epidermis
What is the stratum corneum made up of?
Are squamous cells which have lost their nucleus
What does it mean by the stratum corneum being cornified?
Means they’re full of keratin thus tough to injury
What are between the cells in the stratum corneum layer?
Non-polar lipids are between the cells
What are the other epidermal cell types?
- Melanocytes
- Langerhans cells
- Merkel cells
What do melanocytes synthesise?
Synthesise melanosomes and transfer them to basal keratinocytes through long dendrites
How do keratinocytes arrange melanin pigments?
Keratinocytes arrange melanin pigments in a cap distal to the nucleus
What are langerhans cells involved in?
Involved in the immune system as antigen presenting cells
What type of cells are langerhans cells?
Are dendritic cells
Where does vitamin D production occur?
Made in the epidermis, mostly in the basal cells and also stratum spinosum
What does vitamin D production require?
Requires UV light
Where is vitamin D converted into the active form?
Converted to active form in liver and kidney:
-1,25 dihydroxyvitamin D3
What is the dermis?
Is dense, irregular connective tissue
What does collagen in the dermis provide?
Collagen in the dermis provides tensile strength hence protection against abrasion and impact
What does the dermis contain giving its elasticity?
Contains elastin
What does the dermis carry?
Carries blood and nerve supply for the epidermis
Properties of the dermal epidermal border?
Dermal epidermal border is often wavy to resist shear forces
- Can have finger like dermal papillae
- The epidermis can have rete ridges
What is one effect of UV light on skin?
One effect of UV light on skin is damaged/loss of elastic fibres, resulting in loss of elasticity
-Wrinkles
What syringe do you use for the hypodermis?
Where you put a hypodermic syringe for a subcutaneous injection
What is the hypodermis composed of?
Composed of fat, containing glands, hair follicles, nerves and blood vessels
What is the thickest layer of skin?
The hypodermis
What is the function of the hypodermis?
Function is to provide insulation, cushioning and energy storage
What does the sebaceous gland secrete?
Secretes oily sebum into hair follicles
What is the eccrine sweat glands and what does it secrete?
- Normal sweat glands
- Watery secretions onto skin surface and cools body by evaporation
What does the apocrine secrete?
Secretes oily fluids into hair follicles
Where are apocrine glands found?
Found in armpits and any genital region
What sense organs are present in the skin?
Thermoreceptors -Senses heat or cold Meissner's corpuscle -Senses touch Nociceptor -Senses pain Pacinian corpuscle -Senses pressure
