Dermatology Flashcards
1
Q
Functions of skin
A
- Protective barrier against environmental insults
- Temperature regulation
- Sensation
- Vitamin D synthesis
- Immunosurveillance
- Appearance/cosmesis
2
Q
Skin appendages (4)
A
- Hair
- Nails
- Sebaceous glands
- Sweat glands
3
Q
4 major cell types in epidermis and their roles
A
- Keratinocytes -produce keratin as a protective barrier
- Langerhan’s cells - present antigens and activate T-lymphocytes for immune protection
- Melanocytes - produce melanin, which gives pigment to the skin and protects cell nuclei from UV radiation-induced DNA damage
- Merkel cells - contain specialised nerve endings for sensation
4
Q
4 skin layers and composition
A
- Stratum basale (basal cell layer) - actively dividing cells, deepest layer
- Stratum spinosum (prickle cell layer) - differentiating cells
- Stratum granulosum (granular cell layer) - cells lose their nuclei and contain granules of keratohyaline, Secrete lipid into the intercellular spaces
- Stratum corneum (horny layer) - layer of keratin, most superficial layer
5
Q
What extra skin layer might you find on the sole of the foot?
A
Stratum lucidum - beneath the stratum corneum. Consists of paler, compact keratin.
6
Q
Pathology of the epidermis
A
- Changes in epidermal turnover time, e.g. psoriasis = reduced
- Changes to surface of skin or loss of epidermis, e.g. scales, crusting, exudate, ulcer
- Changes in pigmentation (hypo or hyper)
7
Q
What is the dermis made up of?
A
- Primarily collagen
- Elastin
- Glycosaminoglycans (synthesised by fibroblasts)
Also contains:
- Immune cells
- Nerves
- Skin appendages
- Lymphatics
- Blood vessels
8
Q
Pathology of the dermis
A
- Changes in contour of skin or loss of dermis, e.g. papules, nodules, skin atrophy
- Disorders of skn appendages, e.g. hair, acne (sebaceous glands)
- Changes related to lymphatic and blood vessels
9
Q
List some outcomes of changes to lymphatic and blood vessels in dermis
A
- Erythema (vasodilation)
- Urticaria (increased permeability of capillaries and small vessels)
- Purpura (capillary leakage)
10
Q
3 types of hair
A
- Lanugo hair (fine long hair in fetus)
- Vellus hair (fine short hair on all body surfaces)
- Terminal hair (coarse long hair on scalp, eyebrows, eyelashes, pubic areas)
11
Q
What does a single hair consist of
A
- Modified keratin
Divided into:
- Hair shaft (keratinised tube)
- Hair bulb (actively dividing cells and melanocytes)
12
Q
Hair growth cycle
A
- Anagen (long growing phase)
- Catagen (short regressing phase)
- Telogen (resting/shredding phase)
13
Q
Hair pathology
A
- Reduced or absent melanin pigment production (grey/white hair)
- Changes in duration of growth cycles, e.g. hair loss = premature entry of hair follicles into telogen phase
- Shaft abnormalities
14
Q
Nail
Made up of?
A
- Nail plate (hard keratin)
- Arises from nail matrix at posterior nail fold
- Nail bed contains blood capillaries
15
Q
Nail pathologies
A
- Abnormalities of nail matrix (pits and ridges)
- Abnormalities of nail beds (splinter haemorrhages
- Abnormalities of nail plate (discoloured nails, thickening of nails)
16
Q
Sebaceous glands
PHysiology
A
- Produced sebum via hair follicles
- Secrete sebum onto skin surface to lubricate and waterproof the skin
- Are stimulated by conversion of androgens to dihydrotestosterone (become active during puberty)
17
Q
Pathology of sebaceous glands
A
- Increased sebum production can leas to bacterial colonisation, e.g. acne
- Sebaceous gland hyperplasia
18
Q
Sweat glands
Physiology
A
- Regulate body temp
- Innervated by sympathetic nervous system
19
Q
Sweat glands
Two types
A
- Eccrine - distributed in the skin
- Apocrine - found in axillae, aerolae, genitalia, anus and modified glands are found in external auditory canal. Only function from puberty onwards. Bacteria action on sweat causes body odour.
20
Q
Pathology of sweat glands
A
- Inflammation/infection of apocrine glands (hidradenitis suppurativa)
- Overactivity of eccrine glands (hyperhidrosis)
21
Q
Principle of wound healing
4 stages
A
- Haemostasis
- Inflammation
- Proliferation
- Remodelling
22
Q
Haemostasis processes
A
- Vasoconstriction and platelet aggregation
- Clot formation
23
Q
Inflammation processes
A
- Vasodilation
- Migration of neutrophils and macrophages
- Phagocytosis of cellular debris and invading bacteria
24
Q
Proliferation processes
A
- Granulation tissue formation (synthesised by fibroblasts) and angiogenesis
- Re-epithelialisation (epidermal cell proliferation and migration)
25
Q
Remodelling processes
A
- collagen fibre re-organisation
- scar maturation
