Skin Histology

Question 1

What are the 3 layers of the skin?

Answer 1

1. epidermis
2. dermis
3. subcutis

Question 2

What are the types of cells present in the epidermis?

Answer 2

contains continuously proliferating stratified squamous epithelium

it produces keratin

it is in direct contact with the external environment

it is constantly shed and contains no blood vessels

Question 3

What is present in the dermis?

Answer 3

fibrous and fibroadipose tissue that supports the epidermis, both physically and metabolically

it contains blood vessels, nerves and sensory receptors

Question 4

What is present in the subcutis?

Answer 4

it contains adipose tissue with supporting fibrous bands (septa)

it contains larger blood vessels

Question 5

What type of epithelium is the epidermis?

Answer 5

keratinised stratified squamous epithelium

Question 6

What type of skin is present on the foot?

Answer 6

glabrous skin

this is non-hair bearing and thick skin

Question 7

What are the 5 layers of the epidermis that are present in thick skin?

Answer 7

1. stratum basale - basal cell layer
2. stratum spinosum - prickle cell layer
3. stratum granulosum - granular layer
4. stratum lucidum
5. stratum corneum - keratin layer

Question 8

What layer of the skin is not present in thin skin?

Answer 8

stratum lucidum

Question 9

What is shown by letters a-e in this picture?

Answer 9

a - stratum basale

b - stratum spinosum

c - stratum granulosum

d - stratum lucidum

e - stratum corneum

Question 10

What is shown by the letters in the high magnification of keratinised squamous epithelium?

Answer 10

b - stratum spinosum

c - stratum granulosum

e - stratum corneum

Question 11

What is shown in this image?

Answer 11

resin section of stratified squamous epithelium

Question 12

What is shown in the image?

What is the composition of this layer like?

Answer 12

stratum lucidum of the sole of the foot

this consists of several layers of flattened dead cells

nuclei already begin to degenerate in the outer part of the stratum granulosum

in the stratum lucidum, faint nuclear outlines are visible in only a few of the cells

Question 14

What 3 types of cells are found in the epidermis?

Answer 14

• keratinocytes
• melanocytes
• langerhans cells

Question 15

What type of cell is shown here?

What is their role?

Answer 15

melanocytes

these produce melanin (skin and hair colour)

they are transferred to the keratinocytes through a network of melanocyte cytoplasmic processes

Question 16

What is shown in this image?

Answer 16

Langerhans cells

these are intra-epidermal antigen presenting cells

they are present in all layers of the epidermis but are most easily recognised in the prickle cell layer

Question 17

How can Langerhans cells be recognised?

Answer 17

they are pale-staining in the epidermis

they have irregularly lobulated nuclei and almost clear cytoplasm

cytoplasmic processes (CP) extend from the cells and insinuate between keratinocytes of all layers

Question 18

Where are keratinocytes present?

Answer 18

they are present in all layers of the epidermis, but are most easily recognised in the prickle cell layer

they are present in the upper dermis, particularly around small blood vessels

when stimulated, they migrate to the dermis and then via lymphatics to the lymph nodes

Question 19

What structures are labelled in the diagram?

Answer 19

Question 20

What is the role of the sebaceous glands?

Answer 20

they secrete sebum

one type is associated with the hair follicle and secretes sebum into the hair follicle

the other type secretes sebum directly onto the surface of the skin

Question 21

What is the role of eccrine glands?

Answer 21

they have a thermoregulation function and produce sweat

they are the major sweat glands of the human body that are found in virtually all skin

they have the highest density in the palm and soles and lowest density on the trunk and extremities

Question 22

What is the role of the apocrine glands?

Answer 22

apocrine glands in the skin and eyelid are sweat glands

most are found in the armpits, groin and area around the nipples

apocrine glands in the skin are scent glands and their secretions usually have an odour

Question 23

What is the role of the arrector pili muscle?

Answer 23

it is a bundle of smooth muscle fibres

it inserts at one end into the follicle sheath just below the sebaceous glands and the other in the superficial dermis

Question 24

What is shown in this image?

Answer 24

hair bearing skin

Question 25

What is shown in this image?

Answer 25

**pilosebaceous unit** this consists of hair, sebaceous gland and arrector pili muscle this image is from the scalp

Question 26

What is shown by a, b and c?

Answer 26

a - arrector pili b - hair follicle c - sebaceous gland

Question 27

What are the 4 different types of skin receptors?

Answer 27

* meissner corpuscles * merkel cells * pacinian corpuscles * ruffini endings

Question 28

What is the role of meissner corpuscles?

Answer 28

they are an encapsulated body in the papillary dermis they are fast-adapting discriminatory touch and vibration receptors

Question 29

What is the role of Merkel cell neurites?

Answer 29

they are slow-adapting discriminatory touch and pressure receptors

Question 30

What is the role of Pacinian corpuscles?

Answer 30

they are encapsulated bodies in the deep skin they are fast-adapting for rapid vibration

Question 31

What is the role of Ruffini endings?

Answer 31

they detect stretching and shearing

Question 32

What is shown here?

Answer 32

fingertip

Question 33

What is shown in this image of the fingertip?

Answer 33

each lamella is composed of flattened Schwann cells and endoneurial fibroblasts there is fluid between each layer delicate collagen fibres may be present as well as occasional capillaries

Question 34

What cells are shown here and what type of staining is used to see them?

Answer 34

**CK20** staining is used for **Merkel cells** these are intra-epidermal receptors for touch they are rounded cells without dendritic processes found in the basal layer of the epidermis they are associated with a myelinated nerve forming a Merkel cell-neurite complex

Question 35

What is shown in this image?

Answer 35

**Meissner's corpuscles** these are an encapsulated body in the papillary dermis they are fast-adapting discriminatory touch and vibration receptors

Question 36

What is meant by a first degree burn?

Answer 36

an injury that affects only the outer layer of skin - the epidermis symptoms of redness, minor inflammation and swelling but no blistering

Question 37

What is a second degree burn?

Answer 37

this affects both the epidermis and dermis there is blistering and some thickening of the skin

Question 38

What is a third degree burn?

Answer 38

this type of burn destroys the whole of the epidermis and the dermis the skin has a widespread thickness and a white, leathery appearance

Question 39

What is a fourth degree burn?

Answer 39

a burn that includes all of the symptoms of a third-degree burn and also extends beyond the skin into the tendons and bones

Question 40

What does the skin look like in a first degree burn? What is capillary refill like?

Answer 40

the skin is red and painful but is not blistered capillary refill blanches and then rapidly refills

Question 41

What does the skin look like in a second degree burn? What is capillary refill like?

Answer 41

the skin is pale pink and painful with blistering capillary refill - blanches but regains its colour slowly

Question 42

What does the skin look like in a third-degree burn? What is capillary refill like?

Answer 42

the skin appears dry or moist, blotchy and cherry red it may be painful or painless and there may be blisters capillary refill - does not blanch

Question 43

What does the skin look like in a fourth degree burn? What is capillary refill like?

Answer 43

the skin is dry and white, brown or black in colour with no blisters it may be described as leathery or waxy it is painless capillary refill - does not blanch

Question 44

How should capillary refill be assessed in burns?

Answer 44

by pressing with a sterile cotton bud, such as a bacteriology swab

Question 45

Which layers of the skin are affected in all 4 types of burn?

Answer 45

**first degree burn:** * the epidermis is affected, but the dermis is intact **second degree burn:** * the epidermis and upper layer of the dermis are involved **third degree burn:** * the epidermis, upper and deeper layers of the dermis are involved **fourth degree burn:** * the burn extends through all layers of the skin to subcutaneous tissues