Structure and function of skin

Question 1

What are the three layers of the skin?

Answer 1

Epidermis - outer layer

Dermis - connective tissue

Subcutaneous - fat layer

Question 2

Where does the epidermis come from embryologically?

Answer 2

Ectoderm cells forming a single layer periderm

Question 3

Where does the dermis come from embryologically?

Answer 3

Mesoderm

Question 4

What are melanocytes?

Answer 4

Pigment producing dendritic cells

Question 5

Where do melanocytes come from embryologically? When?

Answer 5

Neural crest

The first 3 months of development

Question 6

What are Blaschko’s lines?

Answer 6

Developmental growth pattern of the skin

Question 7

What are the appendages of the skin?

Answer 7

Nails
Hair
Glands
Mucosae

Question 8

What cell types make up the epidermis?

Answer 8

Keratinocytes - 95%

Melanocytes
Merkel cells
Langerhans cells

Question 9

What type of epithelium is the epidermis?

Answer 9

Stratified squamous epithelium

Question 10

What are the four cell layers of the epidermis?

Answer 10

Keratin layer

Granular layer

Prickle cell layer

Basal layer

Question 11

Hoe long does it take keratinocytes to migrate from the basement membrane to the epidermis?

Answer 11

28 days

Question 12

What can be found in the basal layer?

Answer 12

Intermediate filaments - keratin

Question 13

What are the main basal layer properties?

Answer 13

One cell thick

Small cuboidal cells

Highly metabolically active

Question 14

What is found between the epidermis and dermis?

Answer 14

Dermo-epidermal junction

Question 15

What are the three skin layers at 4 weeks gestation?

Answer 15

Periderm

Basal layer

Dermis (corium)

Question 16

What are found in the prickle cell layer?

Answer 16

Desmosomes - connections

Question 17

What connects to desmosomes?

Answer 17

Intermediate filaments

Question 18

What cells make up the prickle cell layer?

Answer 18

Large polyhedral cells

Question 19

How many layers of cells make up the granular layer?

Answer 19

2-3 layers

Question 20

What bodies are present in the granular layer?

Answer 20

Odland bodies - lamellar bodies

Question 21

What are Odland bodies?

Answer 21

Secretory organelles that contribute to the skin barrier

Question 22

Which granules are found in the granular layer of the skin?

Answer 22

Large keratohyalin granules

Question 23

Which layer has a high lipid content and a loss of cell nuclei?

Answer 23

Granular layer

Question 24

What is the keratin layer made up of?

Answer 24

Corneocytes

Question 25

What are corneocytes?

Answer 25

Overlapping non-nucleated cell remnants

Question 26

What is the key functional property of the keratin layer?

Answer 26

It is a tight waterproof barrier

Question 27

What is 80% of the keratin layer made up of?

Answer 27

Keratin and filaggrin

Question 28

What are the organelles found in melanocytes called?

Answer 28

Melanosomes

Question 29

What is converted to melanin in melanocytes?

Answer 29

Tyrosine

Question 30

What is the difference between melanosomes in lighter and darker skin types?

Answer 30

Darker skin types have larger melanosomes which contain more melanin than lighter skin types

Question 31

What is eumelanin?

Answer 31

Melanin that gives a brown / black pigment

Question 32

What is phaeomelanin?

Answer 32

Melanin that gives a red / yellow pigment

Question 33

Is there more eumelanin or phaeomelanin in darker skin types?

Answer 33

Eumelanin

Question 34

What is the mesenchymal origin of Langerhans cells?

Answer 34

Bone marrow

Question 35

Where can Langerhans cells be found?

Answer 35

Prickle cell layer Dermis Lymph nodes

Question 36

Where are Merkel cells found?

Answer 36

Between keratinocytes and nerve fibres

Question 37

What are Merkel cells?

Answer 37

Basal mechanoreceptors

Question 38

Which oral mucosa is keratinised? Which is non-keratinised?

Answer 38

Masticatory mucosa Lining mucosa

Question 39

What type of organ is the skin?

Answer 39

Neuroimmunoendocrine organ

Question 40

Where do blood vessels run in the skin?

Answer 40

Dermis

Question 41

What are the functions of the dermo-epidermal juntion?

Answer 41

Give support and anchorage to the growth and differentiation of basal cells Semi-permeable membranes acting as a barrier and a filter between the dermis and epidermis

Question 42

What two proteins are essential in the dermo-epidermal junction?

Answer 42

Desmosomes Hemidesmosomes

Question 43

What allow the bypass of superficial capillaries when cold?

Answer 43

\Shunts - AV anastomoses

Question 44

What happens in the overabundance of vessels in the skin?

Answer 44

Angioma

Question 45

What are the two key immune functions of lymphatic vessels?

Answer 45

Allowing passage of Langerhans cells to lymph nodes Channelling of micro-organisms / toxins

Question 46

What type of special receptor detect pressure?

Answer 46

Pacinian corpuscles

Question 47

What type of special receptor detect vibration?

Answer 47

Meissner's corpuscles

Question 48

What skin layer can Meissner's corpuscles be found in?

Answer 48

Dermis

Question 49

What skin layer can Pacinianq corpuscles be found in?

Answer 49

Subcutaneous

Question 50

What are the three main types of skin gland?

Answer 50

Sebaceous Apocrine Eccrine

Question 51

What is produced by sebaceous glands?

Answer 51

Sebum - squalene, wax esters, cholesterol and free fatty acids

Question 52

What is produced by apocrine sweat glands?

Answer 52

Produce oily fluid that have an odour after bacterial decomposition

Question 53

What type of nerve supply controls eccrine sweat glands?

Answer 53

Sympathetic cholinergic nerves

Question 54

What is the main function of eccrine sweat glands?

Answer 54

Cooling by evaporation

Question 55

What four components make up a pilosebaceous unit?

Answer 55

Hair follicle Hair shaft Arrector pilli muscle Sebaceous glands

Question 56

What are the three main segments of a hair follicle?

Answer 56

Infundibulum Isthmus Hair bulb

Question 57

What are the four phases of hair growth?

Answer 57

Anagen Catagen Telogen Exogen

Question 58

What is the growing phase of hair follicles?

Answer 58

Anagen

Question 59

What is the involuting phase of hair follicles?

Answer 59

Catagen

Question 60

What is the resting phase of hair follicles?

Answer 60

Telogen

Question 61

What are the three types of hair follicle?

Answer 61

Lanugo (in utero) Vellus Terminal

Question 62

What is the average growth rate of nails?

Answer 62

0.1mm per day

Question 63

What are the three regions of a fingernail?

Answer 63

Nail plate Lateral nail fold Lunula

Question 64

What are sebaceous glands?

Answer 64

Holocrine secretions opening into a pilary canal

Question 65

From tip to base, what are the layers underneath a fingernail?

Answer 65

Epidermis Hyponychium Nail bed Nail matrix

Question 66

What is the shedding phase of hair follicles?

Answer 66

Exogen

Question 67

Give some key functions of the skin?

Answer 67

Physical barrier Metabolism Thermoregulation Immune defence Sensory functions

Question 68

What two metabolic pathways are carried out in the skin?

Answer 68

Vitamin D metabolism Thyroid hormone metabolism - 80%