Hair, skin and nails Flashcards
Integumentary system and functions
- Skin, hair, sweat glands, sensory receptors
- Functions: homeostasis, stores blood, protection from external environment, cutaneous sensation, excretion and absorption of substances, vit D synthesis
4 overarching layers of skin
Epidermis (outer layer)
Demris
Subcunaeous layer (blood vessels etc)
Hypodermis
Epidermis
Protection
Keratinised, stratified squamous
Stratum germinativum
Skin cells multiply and move away from blood supply
Thick skin
Palms of hand, soles of feet, contains stratum lucid
Thin skin
Rest of body - palms and soles
No stratum lucid
Function of keratinocytes
Make keratin and lamellar granules (water repellant sealant)
Where are melanocytes found
Stratum spinous
Function of melanocytes
Produce melanin to give skin colour
What are Langerhans cells
Macrophages in the skin, easily damaged by UV
Function of Merkel cells
In contact with Merkel discs - detects fine touch
How do we detect discriminatory touch
Merkel cells (epidermis) and Meissner’s corpuscles (dermis)
Which cells detect deep sensation and pressure?
Pacinian corpuscles
Layers of the epidermis
Corneum: continuously sheds dead keratinocytes
Lucidum: keratin
Granulosum
Spinosum: keratonicytes, Langerhans cells
Basale: metabolically active to make new keratinocytes, forms basement membrane
Keratinisation
Newly formed epidermal cells from stratum basal to move outwards
What molecules give dermis its tensile strength
Elastin and collagen
2 regions of dermis
Papillary: dermal papillae project into epidermis, contains blood vessels and nerves
Reticular region: thicker, attached to subcutaneous layer, fibroblasts and connective tissue
Function of melanin
Protects epidermal cells from UV and DNA changes
What are commensal bacteria
Good bacteria to protect from bad
What is sebum
Oily surface film with bactericidal chemicals
Striae
Stretch marks
Damage to dermis
Disrupted lateral bonds between collagen fibres
Keloid scars
Overhealing leads to lumpy scar
Skin tension lines
Langer’s lines - where collagen fibres run in one direction
Important in plastic surgery
Which three chemicals determine skin colour?
Melanin, haemoglobin and carotene (yellow-orange
What are the two types of melanin and their colours?
Phenpmelanin (yellow-red) and eumelanin (brown-black)
Freckles are accumulations of melanin
What is carotene a precursor of?
VitA
Albinism
Inability to make melanin - red eyes, prone to skin cancer
Vitiligo
Lose patches of melanocytes and melanin
Function of arrector pili muscles
Stand hair on end
What are the two types of sweat glands and their characteristics?
Apocrine sweat lands (causes BO, axillary and genitals)
Eccrine sweat glands (everywhere else on body, salty water)
Different hair colours and their melanin proportions
- Dark hair = lots of eumelanin
- Blonde and red hair = lots of pheomelanin
- Grey hair = less melanin production
- White hair = no melanin
What is Laguno hair?
Fine hair in babies
Stages of scalp hair growth
Scalp hair has 3 stages: growth (2-3y), regression (2-3w) and resting (2-3m) and then it is shed
Hirsutism
Excessive body hair
Different sections of a hair
Shaft Follicle Root Bulb Sebaceous
What is the germinal matrix?
Where nail grows from
What is a nail made from
Dead, keratinised epidermal cells
What is the eponychium?
The cuticle - stratum corneum
What is the lunula?
Thick white part of the nail
