Structure & Function & Basics

Question 1

What is the largest organ in body?

Answer 1

Skin

Question 2

The epidermis is composed of which type of epithelium

Answer 2

Stratified squamous

Question 3

The epidermis originates from which embryonic layer

Answer 3

Ectoderm

Question 4

The dermis originates from which embryonic layer

Answer 4

Mesoderm

Question 5

Gastrulation occurs how many days after foetal development?

Answer 5

7-10 days

Question 6

Melanocytes are produced where?

Answer 6

Neural crest

Question 7

At 4 weeks what layers of skin are present?

Answer 7

Periderm, basal and dermis (AKA corium)

Question 8

At 16 weeks how many layers of skin are present?

Answer 8

5 (keratin, granular, prickle cell, basal and dermis)

Question 9

At which age do skin appendages (e.g. follicles) appear?

Answer 9

26 weeks

Question 10

Blaschko’s lines are indicative of what

Answer 10

Problems in early skin development

Question 11

What are the layers of mature skin? (5)

Answer 11

• Epidermis
• Appendages (e.g. nails, hair, glands)
• Dermo-epidermal junction
• Dermis
• Sub-cutis

Question 12

What is the main content of epidermis?

Answer 12

Keratinocytes

Question 13

Keratinocytes move “upwards” through 4 distinctive layers of the epidermis, they are:

Answer 13

Keratin layer (sloughed off), granular layer (presence of granules), prickle cell layer (prickly due to psuedopodia) and basal layer

Question 14

In terms of cell turnover, psoriasis is simply a condition of cells turning over faster/slower than they should

Answer 14

Faster

Question 15

The basal cell layer is usually ___ thick and is composed of _____

Answer 15

One cell thick.

Small cubodial cells.

Question 16

The basal layer is highly metabolically active. True/false?

Answer 16

True

Question 17

The Prickle Layer has lots of desmosomes and intermediate filaments. True/false?

Answer 17

True

Question 18

The granules of the granular layer mainly contain which proteins (2)?

Answer 18

Filaggrin & involucrin

Question 19

What’s the distinguishing histological feature of granular layer?

Answer 19

Odland bodies (AKA Lamellar bodies)

Question 20

Granular layer cells have a high/low fat content & why?

Answer 20

High (preparing to make water-tight proteins)

Question 21

The keratin layer is composed of which cell mainly

Answer 21

Corneocytes

Question 22

What’s the important function of the keratin layer?

Answer 22

Forms a water-tight barrier allowing to live without water loss.

Question 23

Other epidermal cells (not keratinocytes) include (3):

Answer 23

• Melanocytes (basal and suprabasal)
• Langerhans Cells (suprabasal)
• Merkel Cells (basal)

Question 24

Melanocytes migrate from the neural crest at which point in development?

Answer 24

First 3 months

Question 25

Which organelle produces pigment in melanocytes?

Answer 25

Melanosomes

Question 26

Melanin is produced from which precursor?

Answer 26

Tyrosine

Question 27

The two types of pigment include:

Answer 27

- Eumelanin (black/brown) | - Phaeomelanin (red/yellow)

Question 28

Mleansoomes are transferred to adjacent keratinocytes via which structures?

Answer 28

Dendrites

Question 29

Melanocyte stimulating hormone is very large/small and is produced from which hormone?

Answer 29

Small (7AAs) and produced from ACTH

Question 30

How many genes must be lost in order to produce clinical albinism?

Answer 30

4

Question 31

What is the clinically "opposite" condition to albinism?

Answer 31

Nelson's Syndrome (excess MSH)

Question 32

Langerhans cells are from which origin and site?

Answer 32

Mesenchymal from bone marrow

Question 33

Langerhans cells are closely associated with which cell in the epidermis?

Answer 33

Prickle cells

Question 34

Langerhans cells have which function in the skin?

Answer 34

Immune (APC cells)

Question 35

The histologically distuinguishing marker of Langerhans cells is

Answer 35

Racket Organelles AKA Birbeck Granules

Question 36

What is the function of the birbeck granule?

Answer 36

Unknown

Question 37

Merkel cells have which function?

Answer 37

Touch (mechanoreceptor)

Question 38

Merkel cells are present at which cell level?

Answer 38

Basal

Question 39

The hair follicle is AKA....

Answer 39

Pilosebacous unit

Question 40

Hair pigmentation is provided from melanocytes above which structure?

Answer 40

Dermal papillae

Question 41

What are the 3 phases of hair growth?

Answer 41

- Anagen (growing) - Catagen (dying) - Telogen (dead)

Question 42

Male pattern baldness occurs in which pattern?

Answer 42

Hamilton Patterns

Question 43

Alopecia areata is caused by what (general)?

Answer 43

Auotimmune

Question 44

What are the 3 distinctive sub-layers of DEJ?

Answer 44

- Lamina lucida - Lamina densa - Sub-lamina densa zone

Question 45

Bullous pemphigoid is caused by what (roughly)?

Answer 45

Antibodies against the DEJ proteins B230 and B280

Question 46

What's the definitive test for bullous pemphigoid?

Answer 46

Immunofluorescence of skin biopsy for antibodies

Question 47

Mitten deformities can be a sign of which condition?

Answer 47

Epidermolysis bullosa

Question 48

The dermis is composed of which cells? (5)

Answer 48

Fibroblasts, macrophages, masts cells, lymphocytes and Langerhans cells

Question 49

What keeps skin "plump"?

Answer 49

Collagen and elastin fibres (as elastin increases, more wrinkles appear)

Question 50

Are skin lymphatics muscular?

Answer 50

No

Question 51

Lymphodema can result in which skin problems? (2)

Answer 51

Cobblestoning & scailing

Question 52

Pacinian corpuscles cells sense what?

Answer 52

Pressure (lower, look like onions)

Question 53

Meissener's cells sense what?

Answer 53

Vibration (and fine touch, high in epidermis - c.f. Pacinian which sense "deep" pressure

Question 54

The apocrine glands are mainly where?

Answer 54

Genitals and sweating areas

Question 55

The eccrine glands are what? Are they common

Answer 55

Sweat glands. Yes, commonest in body.

Question 56

Sebum is produced from what precusors (4)

Answer 56

- Squalene - Wax esters - Triglycerides - FAs

Question 57

What is the function of the sebaceous gland physiologically (2)

Answer 57

- Prevent moisture loss | - Protect against fungal infection

Question 58

Eccrine glands are under what kind of control?

Answer 58

sympathetic, cholinergic

Question 59

What's a common iatrogenic cause of TEN?

Answer 59

Allopurinol posioning

Question 60

Metabolically, the skin is involved which metabolism of which nutrients?

Answer 60

Vitamin D & thyroid hormones

Question 61

The conversion of cholecalciferol to vitamin D3 occurs at which wavelength?

Answer 61

290-320nm

Question 62

Vitamin D3 is converted to vitamin D where?

Answer 62

Kidney

Question 63

80% of conversion of T4 to T3 occurs where?

Answer 63

Skin

Question 64

How to keratinocytes contribute to immunity?

Answer 64

Produce AMPs, cytokines and chemokines

Question 65

Langerhans cells are a type of dendritic cell. True/false?

Answer 65

True

Question 66

In epidermis, what is the main subtype of T-cell? How does this vary from dermis?

Answer 66

CD8+ along with NK cells. Differs from dermis which has CD4+ and CD8+

Question 67

Psoriasis is associated with activation of which T-helper cell subtype?

Answer 67

TH1

Question 68

Atopic dermatitis is assoicated with activation of which t-helper cell subtype?

Answer 68

TH2

Question 69

TH1 cytokines include (2)

Answer 69

IL2, IFN gamma

Question 70

TH2 cytokines include (3)

Answer 70

IL4, IL5, IL6

Question 71

Which type of dendritic cell produces IFN alpha in diseased skin?

Answer 71

Plasmacytoid DCs

Question 72

MHC molecule is found on what chromosome?

Answer 72

6

Question 73

Atopic eczema characteristically an impairment of what, usually due to what?

Answer 73

Impairment of skin barrier due to mutated filaggrin gene

Question 74

Atopic eczema is mainly which type of immune response

Answer 74

TH2

Question 75

Type 1 hypersensitivity is mediated by which antibody?

Answer 75

IgE / histamine

Question 76

Type 2 and 3 hypersensitivities are mediated by what?

Answer 76

IgG and IGM (type 3 is complex)