Hair and Nails Flashcards
What are the functions of Hair
- Protection: from UV, physical ( eyelashes)
- Sensation: which helps to amplify sensation.
- Thermoregulation: sweat evaporation more effectively from hair with greater surface area.
- Communication: hair products etc
What do hair and nails have in common?
Protein product of their hair follicle and nail matrix
What is hair and the hair follicle
Keratin: being a structural protein.
Hair follicle: mini organ. Complex interaction of cytokines under autonomous control.
What are the 3 types of hair
Terminal hairs: long and thick hair. This expands during puberty in response to androgens. Start as vellus hair.
Vellus hair – short and thin hair soft, unmedulated , usually non pigmented –
lanugo – long and thin hair are fine, unpigmented in the fetus at 20 weeks. Normally shed before birth but may be seen in premature or in anorexia.
decribe the structure of the hair follicle
Hair bulb: where the hair grows from, sits in the mid/deep dermis
Arrector pilli muscle: raise the hairs in shivering, to keep warm
Sebaceous gland- lubricate the hair
What are the 3 parts the follicle can be divided into
Infundibulum – surface of skin to opening of the sebaceous glands
Isthmus – gland to insertion of arrector pilli muscle
[suprbulbuar) – outer and inner root sheath. Inner moulds the shape of the hair fibre.
Bulb- fed by blood from the dermal papilla
What is the hair structure
Cortex, Medulla, Outer cuticle
What are the stages at which the hair grows
Anagen: growth phase, most are in this stage
Catagen: cell division slows and stops.
Telogen: hair is shed actively and the next anagen phase begins
Anagen is the growth phase and is an energy intensive process. Normally 85% of hairs are in this stage.
Catagen is when cell division slows and stops. The end of the shaft keratinizes and forms a club shape. The dermal papilla and the club move towards the base of the muscle insertion.
In telogen, hair is shed actively and the next anaphase begins. The club hair can take 4-6 weeks to be released.
What is the function of nails
Protection: chemical/physical
Touch: manual dexterity
Communication: socially
What is the structure of nails
Mostly hard alpha keratin.
Strong- longitudinal ridging, curvature
Describe the features of hair growth and how many phases?
It is random, synchronisation in pregnancy and happens in 3 phases
How does nail grow?
The nail matrix contains dividing cells which mature, keratinize and move forward to form the nail plate.
