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The Patient (Y3-1) > Skin > Flashcards

Flashcards in Skin Deck (57)
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What are the four layers of the epidermis?



What is the main function of the epidermis?

Replace damaged cells - to maintain skin's protective properties


Which two cells are contained in the stratum basale layer?



How does the skin replace damaged cells?

Continual production of keratinocytes - these are pushed up through the four layers of the epidermis until they are shed


What is the role of melanocytes?

Production of melanin which acts to protect the skin from UV by absorbing it. Melanin is produced on exposure to sunlight


What is the role of the stratum spinosum?

Anchors cells together by interlocking cytoplasmic processes


What takes place in the stratum granulosum?

Cells undergo enzyme-induced destruction - losing their nuclei and cytoplasmic organelles.
Lipid-rich secretions acting as the skins water sealant
Keratin is laid down, further meshing structures together


What does the stratum corneum consist of?

Dead cells which are flattened and contain densely packed keratin
Corneocytes are shed from the skin


What is the function of the dermis?

Provides strength (contains fibroblasts and collagen) but also provides elasticity (contains elastin)


Name some specialised structure that are present within the dermis

Sweat glands
Smooth muscle


What is the function of the hypodermis?

Cushions and insulates tissue below the hypodermis


Which layer of the skin contains fat?



What are the three layers of the skin from top to bottom?



What are the four main functions of the skin?

Production of Vitamin D
Sensory organ for touch, pain and temperature
Controls body temperature
Barrier to protect tissues and organs


Describe the function of the skin in producing vitamin D

7-dehydrocholestrol in the skin produces vitamin D3 (cholecalciferol) in the presence of sunlight/UV
Vit D3 is then converted into calcidiol in the liver
calcidiol -> calcitriol in the kidney
calcitriol is the active form of vitamin D


How does vitamin D increase calcium levels?

It stimulates intestinal epithelium to produce more carrier protein molecules for calcium transport


Name three sensory receptors in the skin and outline their role

Mechanoreceptors - light touch and deep pressure detection
Thermoreceptors - warmth and cold detection
Nociceptors - respond to pain


Describe the role of the skin in controlling body temperature

Contains capillaries
In hot weather - capillaries open, increasing blood flow = vasodilaton -> heat loss at surface of skin
In cold weather - vasoconstriction -> minimising heat loss
Sweat glands actively secrete water and salts when body temperature is above 37 to cool body down


The skin acts as a protective barrier for tissues and organs. Name four things it protects against

Mechanical damage and trauma
UV radiation


Which cells in the skin are involved in the immune response against foreign matter and where are they found?

Langerhans cells found in the epidermis. They are antigen-presenting and so ingest the foreign particles and present them to T and B cells to induce immune response


What are the four phases in the healing process of the skin?

Inflammatory phase
Proliferative phase
Maturation phase


What events take place if the epidermis of the skin is broken as a result of a burn/graze?

Keratinocytes in the stratum basale break from the basement membrane.
They enlarge and move across the wound until they meet another cell = contact inhibition, where growth and stops


What happens in the haemostasis stage of skin healing, following injury to the epidermis and dermis?

Main priority is to stop bleeding
Platelets recognise exposed collagen in the exposed dermis. They become sticky and release thromboxane A2. Platelets are now activated and begin to aggregate, forming a temp. plug.
Seratonin is released from activated platelets and works to reduce blood supply around the wound.
Both the plug and vasoconstriction reduce blood loss from the injury.
Thromboplastin, released from damaged tissues combines with calcium to form insoluble fibrin at the end of the clotting cascade
The fibrin combines with platelet aggregates to form a clot, and if this is left uncovered -> dries -> scab


What takes place in the inflammatory phase of skin healing?

The main aim is to clean the wound
Langerhans cells are activated and release inflammatory mediators
Bradykinin increases pain at the site
Leukotrienes increase blood flow causing the skin to warm
There is an increase in vascular permeability, allowing WBCs to move to the wound from the blood
WBCs produce neutrophils which digest bacteria
Monocytes then move to the wound, maturing into macrophages which continue the wound cleaning process throughout healing


What takes place in the proliferative stage of skin healing?

Main aim is dermis repair and epidermis regeneration
Macrophages commence this stage
If the wound has low oxygen levels, macrophages release angiogenic growth factors to develop new blood vessels
Macrophages release chemicals to attract granulation tissue to the wound -> new connective tissue
Platelet derived growth factors and macrophages activate fibroblasts which grow and divide to produce a collagen network to strengthen the wound
Epithelial cells move over the top of the moist granulation tissue. Once the cells meet at the top of the wound, they stop due to contact inhibition


What takes place in the maturation stage?

The phase forms a scar. This can take up to 2 years
Collagen is re-aligned to improve strength. Collagen strands pull the wound inwards
Extra blood vessels close


Which intrinsic patient factors affect the wound healing process?

Nutrition - vitamins and proteins needed
Skin perfusion - disease such as peripheral vascular disease can affect this and so reduce O2 levels
Age - younger patients better perfusion


Which extrinsic factors affect the wound healing process?

Moist wound - better
Wound temp - 37 degrees optimal
Tissue oxygenation
Clean wound surface


Where are sebaceous glands found?



What is isotretinoin used for and what is its mechanism of action?

Treatment of severe acne, unresponsive to topical treatments and oral antibiotics
Reduces sebum excretion by ~90% after 6 weeks
Decreases hyperkeratinisation
Anti-inflammatory effects