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Tissues > 11. Hair and Nails > Flashcards

11. Hair and Nails Flashcards

1
Q

Function of hair

A

Protection (against UV damage)
Sensation (sensory innervation within follicles which can amplify sensation)
Thermoregulation (minimal in humans)
Communication

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2
Q

What are hair and nails comprised of?

A

Keratin

Products of hair follicle and nail matrix (respectively)

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3
Q

Where is hair?

A

Everywhere except mucous membranes, palms and soles

Only 5% of hair is on scalp

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4
Q

When does hair start growing?

A

3rd Trimester in utero

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5
Q

What is the pilo sebaceous unit comprised of?

A

Hair follicle
Hair shaft
Arrector pili muscle
Sebaceous gland

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6
Q

What is a hair follicle?

A

Invagination of epidermis containing a hair

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7
Q

What is the hair shaft comprised of?

A

Outer cuticle that encloses a cortex of packed keratinocytes

+ An inner medulla (in terminal hairs)

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8
Q

Where are germinative cells and melanocytes found?

A

In hair bulb

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9
Q

Arrector pilli muscle (autonomic control) is vestigal in humans

A

Contracts with cold, fear and emotion

To erect hair, produces goose pimples

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10
Q

Where are sebaceous glands found?

A

Associated with follicles, especially those of the scalp, face, chest and back

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11
Q

What are sebaceous glands formed of and what do they produce?

A

Formed of epidermis derived cells

Produce an oily sebum

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12
Q

When do sebaceous glands become large and active?

A

At puberty

As sensitive to Androgens

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13
Q

How is Sebum produced?

A

By holocrine secretion

In which cells disintegrate to release their lipid cytoplasm

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14
Q

Name the 3 types of hair

A

Lanugo
Vellus
Terminal

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15
Q

Describe Lanugo hair

A

Fine and long
Formed in fetus at 20 weeks.
Normally shed before birth but may be seen in premature babies
Occur in anorexia.

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16
Q

Describe Vellus hair

A

Short, fine and light coloured

Cover most of body

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17
Q

Describe Terminal hair

A

Longer, thicker and darker.
Found on scalp, eyebrows, eyelashes, and pubic, axillary and beard areas.
Originate as a vellus hair, differentiation is stimulated at puberty by androgens.

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18
Q

Pubic Louse

A

Adapted to grip terminal hair
Related to gorilla louse
Eyelashes – site for pubic louse attachment

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19
Q

Head lice and body lice are genetically different

A

Head lice only target hair on head - do not carry disease

Body lice can carry disease and do not target hair on head

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20
Q

Demodex mite

A

lives inside hair follicle of everyone,

not harmful

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21
Q

What is the only type of hair that a medulla is found in?

A

Terminal

22
Q

How are hair fibres composed?

A

Keratin protein forms filaments which are supercoiled to form larger filaments, grouped/ linked together to form strong strands

23
Q

Genetic defects in keratin

A

causes genetic syndromes with effects on hair, skin and nails

24
Q

The Hair cycle

A

Anagen- Growing phase
Catagen- Resting phase, stops growing
Telogen- Sheds

25
Q

Different hairs in different locations have different

A

Anagen length

determines maximum length of hair

26
Q

Synchronicity of hair

A

Hair in synchronicity at birth
All hairs synchronise,
Leading to complete hair loss at 3 months

27
Q

What is the normal synchronicity of hair?

A

normal for all hairs to asynchronous

Occurs after birth

28
Q

Telogen effluvium

A 
A cause of hair loss
All hairs become synchronous again
Premature termination of Anagen -->Telogen
Diffuse Hair Loss
Many causes e.g. stress
Regrowth over 3-6 months
29
Q

Testosterone Paradox

A

Hairs become thicker & pigmented
Androgens cause vellus follicle to become terminal follicle
Occurs on scalp of men (androgen sensitive area- Androgenic alopecia)
Causes hair to undergo miniaturisation

30
Q

Miniturisation of hair

A

Each cycle hair becomes slightly smaller until it is wispy

and no follicle is left

31
Q

Female pattern alopecia

A

hair thinning on top of head, but side preserved

androgens have a smaller role as more complex

32
Q

Hirsutism

A

Hairy, in male patterned distribution (when it should not be) e.g. beard
e.g. In females / children caused by excessive androgen drive e.g. By PCOS, Drugs, Excess androgens

33
Q

Alopecia Areata

A

autoimmune condition

Immune privileged state of anagen stops, leading to patchy hair loss

34
Q

Folliculitis

A

Inflammation of follicles e.g. acne

35
Q

Function of nails

A 
Protection (weapon)
–	Chemical, physical
Touch
–	Manual dexterity
Communication 
–	socially
36
Q

Structure of nails

A

Mostly hard “hair” keratin
Strong:
– Longitudinal Ridging
– Curvature

37
Q

What does nail matrix contain?

A

Dividing cells which mature, keratinize and move forward to form nail plate

38
Q

Thickness and growth rate of nail plate

A

Thickness: 0.3-0.5mm

Growth rate: 0.1mm /day (finger nail)

39
Q

What produces the small amount of pink colour of nails?

A

Adjacent dermal capillaries

40
Q

What is the visible part of the nail matrix?

A

White lunula

41
Q

What is the Hyponychium of a nail?

A

Thickened epidermis that underlies the free margin of the nail.

42
Q

What is the nail surface produced by?

A

Proximal nail bed

43
Q

Clubbing

A

Tip of fingers swollen
Nail is distorted >180 degrees
Many disorders cause clubbing e.g. Lung cancer

44
Q

Beau’s Lines

A

Systemic illness or severe trauma causes ridge in nail

45
Q

Koilonychia

A

spoon shaped nails

inherited, can indicate iron deficiency anaemia, hyperthyroid, drugs

46
Q

Psoriasis

A

Pitting in nail
Salmon spots- psoriatic plaques visible under nail
Onycholysis- nail plate splits away from nail bed

47
Q

Yellow nail syndrome

A

Rare

Onset 40-50 with lung/sinus disease

48
Q

Nail Pigmentation

A

Melanonychia Striata or Melanoma

Streaks indicates something in nail matrix is making pigment

49
Q

Systemic sclerosis

A

Giant capillaries

Microhaemorrhages

50
Q

Dermoscopy finding disrupted/ irregular/ thrombosed hairpin vessels on nail cuticle

A

sign of Systemic Sclerosis

Tissues (11 decks)

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