Tissues 11 (Hair & Nails)

Question 1

What are the 3 types of hair?

Answer 1

• Lanugo: wispy/baby hair (shed before birth, found in anorexics)
• Vellous: unpigmented & wispy (covers body)
• Terminal: thick & pigmented (starts as villous & differentiates in puberty by androgens)

Question 2

What are the functions of hair?

Answer 2

• protection
• sensation
• thermoregulation
• communication

Question 3

What are the 3 layers of hair?

Answer 3

• cortex: main structural component (bulk of fibre)
• medullar: presents in larger fibres (spongy - proteins & air spaces)
• outer cuticle: 5-10 overlapping cell layers (keratin deposits, disulphide bonds & fatty acid chains)

Question 4

What is a hair follicle?

Answer 4

complex interaction of cytokines under autonomous control, affected by external factors

Question 5

What are the phases of hair development?

Answer 5

• anagen: energy intensive - 85% growth (2-6yrs)
• catagen: cell division stops, shaft keratinises & forms club shape that moves to base of muscle insertions (2-3wks)
• telogen: hair actively shed, anagen begins again (2-3mths)

Question 6

What is telogen effluvium?

Answer 6

thinning of hair due to early entry of hair

Question 7

What comprises the hair follicle?

Answer 7

• dermal papilla: loop of capillary blood vessels
• hair bulb: hair grows here (fed by blood from dermal papilla)
• suprabulbar: outer & inner root sheath
• isthmus: gland to insertion of arrector pili muscle
• arrector pili muscle: raises hair in shivering
• sebaceous gland: lubricates hair
• infundibulum: surface of skin to opening of sebaceous gland

Question 8

What are nails used for?

Answer 8

• protection
• touch
• communication

Question 9

What is the curvature of nails?

Answer 9

• 2 dimensions
• across proximal to distal

Question 10

what ridging is present in nails?

Answer 10

• longitudinal
• ridged at junction of bed to nails

Question 11

what type of keratin is used in nails?

Answer 11

• alpha
• hard & dense

Question 12

What is the germinal matrix?

Answer 12

• critical for proper nail growth
• lunula: visible 1/2 moon shape at distal end

Question 13

What is the growth of the nail plate?

Answer 13

• surface produced by proximal nailbed
• nail grows out from adhesion
• top of nailplate produced by most proximal portion of matrix

Question 14

What is the speed of nail growth?

Answer 14

• fingernails: 3mm/month
• toenails: 1mm/month
• grow upto 1 week post-mortem

Question 15

What are the labels of the nail?

Answer 15

1. Hyponychium
2. Nail Plate
3. Eponychium
4. Germinal Matrix
5. Lunula
6. Onychodermal Band

Question 16

What are the labels of the hair?

Answer 16

a. infundibulum
b. isthmus
c. suprabulbar
d. hair bulb
1. sebaceous gland unit
2. arrector pili muscle
3. hair bulb
4. germinal matrix
5. dermal papilla