Structure and Function 3 and 4 Flashcards
What forms the interface between the dermis and epidermis?
Dermo-epidermal junction
What are the key roles of the dermo-epidermal junction?
Support, anchorage, growth and differentiation of basal cells Semi-permeable membrane (barrier and filter) Wound healing
What are the 3 layers of the dermo-epidermal junction, from superficial to deep?
- Lamina lucida - Lamina densa - Sub lamina densa zone
What are two conditions which affect the DE junction?
Bullous pemphigoid Epidermolysis bullosa
What is bullous pemphigoid?
Autoimmune condition where the immune system attacks the proteins in the DE junction
Who does bullous pemphigoid occur in?
Older people, especially those with a history of stroke/Parkinson’s
How do you test and treat for bullous pemphigoid?
Test: immunofluorescence for antibodies to the basal membrane Treat: oral steroids
What is epidermolysis bullosa?
Inherited genetic problem at the DE junction
What does the dermis mainly contain? What is the function of these?
Fibroblasts- producing collagen
As well as fibroblasts, what other cells can be found in the dermis?
Macrophages, mast cells, lymphocytes and Langerhan’s cells
What structures are found in the dermis?
Muscles, blood vessels, lymphatics and nerves
Why does photoaging occur?
Collagen is broken down and lost
What is angioma?
Overgrowth of blood vessels
What is neurofibromatosis?
A rare genetic condition causing overgrowth of nerve endings or neural tissue
Lymphatics of the skin allows continuous drainage of what?
Plasma proteins, cells and excess fluids
What are the important functions of the lymphatics of the skin?
Immune surveillance by lymphocytes and Langerhan’s cells Channelling microorganisms and toxins
Are problems with skin lymphatics easy to fix?
No, this is almost impossible
What two types of nerves can be found in the skin?
Somatic sensory (dermatomes) Autonomic
What types of somatic sensory receptors are found in the skin?
Free nerve endings (fine touch) Pacinian for pressure Meissner’s for vibration
Autonomic nerves in the skin supply what?
Blood vessels, nerves and glands
What are hair follicles known as?
A pilosebaceous unit
What is acne?
An abnormality of the pilosebaceous unit where the sebaceous gland gets blocked
What is the function of sebaceous glands?
Control moisture loss and protect from fungal infections
As well as the sebaceous glands, what other gland develops as part of the pilosebaceous unit?
Apocrine glands
Deficiency of what can cause problems with hair growth?
Iron
Where are sebaceous glands most common?
Across the face and chest
What do the sebaceous glands secrete? Into where?
Secrete sebum into the pilar canal
What activates the sebaceous glands? When?
Hormones- once puberty has started
Where are apocrine glands found?
Genital regions, especially axillae and perineum
What hormone are apocrine glands dependent on?
Androgens
What do apocrine glands produce?
An oily fluid which causes an odour
What is the function of apocrine glands?
Unknown
What are eccrine glands and where are they found?
Sweat glands, found all over the skin surface but especially the palms, soles and axillae
What is the nerve supply to eccrine glands? What stimulates them?
Sympathetic, cholinergic nerve supply Mental, thermal and taste stimulation
Eccrine glands allow reabsorption of what?
NaCl and HCO3
What is the function of eccrine glands?
Cool by evaporation, moisten the palms/soles to aid grip
What condition does this show?
Bullous pemphigoid
What condition does this show?
Epidermolysis bullosa
What does this photo show?
Photoaging
What does this picture show?
Angioma
What does this picture show?
Lymphoedema
What does this picture show?
Pacinian corpsucles
What condition does this picture show?
Neurofibromatosis
What condition does this picture show?
Alopecia areata
What condition does this picture show?
Acne
What are the 6 main functions of the skin?
- Barrier function
- Metabolism
- Imune defence
- Thermoregulation
- Communication
- Sensory function
What can happen if the barrier function of the skin fails?
- Water loss and dehydration
- Protein loss and hypoalbuminaemia
- Infection
The skin is involved in whcih two metabolic processes?
Vitamin D and thyroid hormone metabolism
What do the warm and cold thermoreceptors on the skin allow?
They allow us to make behavioural changes such as sweating, shivering and vasodilation/constriction
Is the skin involved in specific or non-specific immune defence or both?
Mainly non-specific, but involved in specific to antigens which have already been encountered
What is toxic epidermal necrosis?
Acute skin failure, most commonly caused by drugs. There is a lot of fluid loss, causing the epidermis to come off the dermis
What is steroid sulphatase deficiency?
X-linked disease which can occur as a side effect of HMG-CoA reductase inhibitors (cholesterol medication)
What is eczema herpeticum?
Disseminated herpes virus infection
What are crusted scabies and what makes them different to scabies?
They occur in people who are immunocompromised- there are many more mites than normal, making them more infectious
What does this picture show?
Toxic epidermal necrosis
What does this picture show?
Erythroderma
What does this picture show?
Steroid sulphatase deficiency
What does this picture show?
Crusted scabies
What does this picture show?
Eczema herpeticum
