Histology

Question 1

What cell type makes up the most outer layer of the skin?

Answer 1

Keratinised stratified squamous epithelium

Question 2

What is Blaschko’s Lines and why are they important?

Answer 2

Developmental growth pattern of skin

If a condition runs along these lines -> inborn error

Question 3

What are the 3 layers of skin?

What appendages can be found within it?

Answer 3

1. Epidermis
2. Dermis
3. Subcutaneous tissue

Hair
Nails
Glands
Mucosae

Question 4

What defines a scar?

Answer 4

No appendages present

Question 5

Name the 4 layers of the epidermis

Answer 5

Keratin layer
Granular layer
Prickle cell layer
Basal layer

(kerry’s gran pricks basil)

Question 6

A loss of control of epidermal turnover can result in what?

Answer 6

Skin cancer

Psoriasis

Question 7

What makes up the majority of the dermis

Answer 7

Collagen fibres (that’s what makes leather …)

Question 8

How long does it take for skin to regenerate? (Keratinocytes migrate from basement membrane)

Answer 8

28 days

Question 9

Describe the histological makeup of basal layer?

Answer 9

One cell thick

Small cubodial

Question 10

What cell type makes up the prickle cell layer?

Answer 10

Larger polyhedral cells

Question 11

How can granular layer be identified on slide?

Granular layer contains filaggrin. True or false?

Answer 11

2-3 layers of flatter cells that have NO NUCLEI

True

Question 12

How does skin retain water and keep hydrated?

Answer 12

Filaggrin found in granular layer and keratin layer (short fillaggrin break-down products = retain water)

Question 13

What layer of the skin is responsible for tight waterproof barrier?

Answer 13

Keratin layer

Question 14

Describe the pattern between kertainisation of mucosal membranes and level of trauma and activity the muscosal layer is subject to

Answer 14

Mucosal layers are more kertainised/are kertainised in areas that need more protection

e.g. kertainised inside mouth
lips = non-keratinised

Question 15

What within a melanocyte produces melanin?

Where are melanocytes found?

Answer 15

Melanosomes

Basal layer - just above dermo-epidermal junction

Question 16

Explain the process by which melanocytes are used to help protect nuclear DNA in basal cells

Answer 16

Melanocytes contain melanosomes.

Melanosomes convert tyrosine -> melanin

Fully converted melanosomes travel to neighbouring keratinocytes where they form a melanin cap over nucleus

Melanin absorbs UV light

Question 17

What causes the variation in skin tone?

Answer 17

Variation in melanin production NOT the difference in number of melanoyctes

Question 18

What drives melanin production?

Answer 18

UV light trigger hormones to convert tyrosine to melanin

Question 19

Where are langerhans cells produced?

Where are they found in the skin?

What is their role?

Answer 19

Bone marrow (mesenchymal origin)

Prickle cell layer (and dermis/lymph nodes)

APC - pick up antigen via bring to lymph
Subset of dendritic cells

Question 20

What are Merkel cells?

Where are they found?

Answer 20

Important for sensation

Basal layer between keratinocytes and nerve fibres

Question 21

What sticks the dermis to epidermis?

Why is it important?

Answer 21

Dermo-epidermal junction

Allows flow of nutrients to epidermis

Provides barrier and filtration

Question 22

What are the 2 parts of the dermis?

Answer 22

Papillary dermis - more surface
- less dense collagen

Reticular dermis - deeper
- more dense collagen

ADD

Question 23

What helps with solute transfer in dermis?

Answer 23

Ground substance (jelly substance)

Question 24

Why are fibroblasts important in dermis?

Answer 24

They produce collagen and elastic fibres etc. for structure and strength

Question 25

What WBC are found in dermis?

Answer 25

- Macrophages - Mast cells - Langerhans cells (o way to lymph from prickle cell layer)

Question 26

What causes wrinkles?

Answer 26

Degradation of elastic fibres caused by UV radiation

Question 27

How do blood vessels flow under the epidermis?

Answer 27

Horizontal plexuses (horizontal to skin layer)

Question 28

There are no blood vessels in the epidermis. True or false?

Answer 28

True

Question 29

What in the skin allows for reception of: Vibrations Pressure Pain Where are they found? What is a distinguishing feature on slides?

Answer 29

Meissner's corpuscle - vibration - dermis just under epidermis - bulb with stem appearance Pacinian corpuscle - pressure - deep dermis - onion ring appearance Free nerve endings - Pain - basal layer of epidermis

Question 30

Name the 3 different types of glands in the skin: - state action of each - where they are found in highest abundance Go to Onenote and complete diagram of position of glands

Answer 30

Eccrine glands - thermoregulation - palms, soles and axilla Sebaceous glands - holocrine secretion - produce sebum into hair follicule to coat hair and skin - largest in face + chest Apocrine glands - likely to feremoan secretion/ odour secretion - axillae/nipples and genitals

Question 31

What kind of collagen is found in skin?

Answer 31

I and III

Question 32

What is perikeratosis?

Answer 32

Nuclei present in the keratin layer

Question 33

What is the most metabolically active layer of the skin?

Answer 33

Basal cell layer

Question 34

Mucosal membranes are highly specialised for function. True or false?

Answer 34

True

Question 35

What cell makes up 95% of epidermal cells and what is its role?

Answer 35

Keratinocytes Vitamin D production

Question 36

What layer of the skin contains obland bodies? What are they and why are they important?

Answer 36

Granular layer Lamellar bodies excreted by keratinocytes that form the high lipid content secretion that acts as a water barrier