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Flashcards in 11. Hair and Nails Deck (50)
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1

Function of hair

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

2

What are hair and nails comprised of?

Keratin
Products of hair follicle and nail matrix (respectively)

3

Where is hair?

Everywhere except mucous membranes, palms and soles
Only 5% of hair is on scalp

4

When does hair start growing?

3rd Trimester in utero

5

What is the pilo sebaceous unit comprised of?

Hair follicle
Hair shaft
Arrector pili muscle
Sebaceous gland

6

What is a hair follicle?

Invagination of epidermis containing a hair

7

What is the hair shaft comprised of?

Outer cuticle that encloses a cortex of packed keratinocytes
+ An inner medulla (in terminal hairs)

8

Where are germinative cells and melanocytes found?

In hair bulb

9

Arrector pilli muscle (autonomic control) is vestigal in humans

Contracts with cold, fear and emotion
To erect hair, produces goose pimples

10

Where are sebaceous glands found?

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

11

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

Formed of epidermis derived cells
Produce an oily sebum

12

When do sebaceous glands become large and active?

At puberty
As sensitive to Androgens

13

How is Sebum produced?

By holocrine secretion
In which cells disintegrate to release their lipid cytoplasm

14

Name the 3 types of hair

Lanugo
Vellus
Terminal

15

Describe Lanugo hair

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

16

Describe Vellus hair

Short, fine and light coloured
Cover most of body

17

Describe Terminal hair

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.

18

Pubic Louse

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

19

Head lice and body lice are genetically different

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

20

Demodex mite

lives inside hair follicle of everyone,
not harmful

21

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

Terminal

22

How are hair fibres composed?

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

23

Genetic defects in keratin

causes genetic syndromes with effects on hair, skin and nails

24

The Hair cycle

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

25

Different hairs in different locations have different

Anagen length
determines maximum length of hair

26

Synchronicity of hair

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

27

What is the normal synchronicity of hair?

normal for all hairs to asynchronous
Occurs after birth

28

Telogen effluvium

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

Testosterone Paradox

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

Miniturisation of hair

Each cycle hair becomes slightly smaller until it is wispy
and no follicle is left

31

Female pattern alopecia

hair thinning on top of head, but side preserved
androgens have a smaller role as more complex

32

Hirsutism

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

Alopecia Areata

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

34

Folliculitis

Inflammation of follicles e.g. acne

35

Function of nails

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

36

Structure of nails

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

37

What does nail matrix contain?

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

38

Thickness and growth rate of nail plate

Thickness: 0.3-0.5mm
Growth rate: 0.1mm /day (finger nail)

39

What produces the small amount of pink colour of nails?

Adjacent dermal capillaries

40

What is the visible part of the nail matrix?

White lunula

41

What is the Hyponychium of a nail?

Thickened epidermis that underlies the free margin of the nail.

42

What is the nail surface produced by?

Proximal nail bed

43

Clubbing

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

44

Beau’s Lines

Systemic illness or severe trauma causes ridge in nail

45

Koilonychia

spoon shaped nails
inherited, can indicate iron deficiency anaemia, hyperthyroid, drugs

46

Psoriasis

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

47

Yellow nail syndrome

Rare
Onset 40-50 with lung/sinus disease

48

Nail Pigmentation

Melanonychia Striata or Melanoma
Streaks indicates something in nail matrix is making pigment

49

Systemic sclerosis

Giant capillaries
Microhaemorrhages

50

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

sign of Systemic Sclerosis