Week 8: Skin histology

Question 1

What are the functions of the skin?

Answer 1

• protection- moisture control, barrier to pathogens, UV
• metabolic function e.g production of VitD
• thermoregulation
• sensory organ
• rapid repair of injury

Question 2

What are the 3 layers of skin?

Answer 2

1. Epidermis
2. Dermis
3. Subcutis

Question 3

What type of cells are found in the epidermis (the most superficial layer)?

Answer 3

keratinised stratified squamous epithelial cells

keratinised just means produces keratin

Question 4

What two layers is the dermis made up of and what does this layer contain?

Answer 4

-papillary dermis (top)
-reticular dermis
made up of fibrous and fibroadipose tissue
contains blood vessels, nerves, muscles and sensory receptors

Question 5

What is the subcutis layer made of?

Answer 5

largely made up of adipose tissue, with supporting fibrous bands and larger blood vessels

Question 6

What does stratified mean?

Answer 6

made up of different layers, where not all of the layers are in contact with the basement layer

Question 7

What does glabrous skin mean?

Answer 7

non-hair bearing

Question 8

What are the 5 layers of the epidermis in thick skin? (from bottom to top)

Answer 8

1. Basal layer / stratum basale
2. Prickle cell layer / stratum spinosum
3. Granular layer / stratum granulosum
4. Stratum lucidum
5. Keratin layer / stratum corneum

Question 9

Which layer of the epidermis is NOT in thin skin/ is only found in thick skin?

Answer 9

stratum lucidum

Question 10

What happens to nuclear integrity as cells move further up the epidermis?

Answer 10

they start to loose nuclear integrity until they reach the top of the epidermis where there is no nuclear detail left

Question 11

What cells do we find in the epidermis?

Answer 11

• keratinocytes
• melanocytes
• langerhans cells

Question 12

What are melanocytes?

Answer 12

• cells responsible for pigment in the skin

- brown pigment = melanin

Question 13

What are langerhans cells?

Answer 13

• found in the upper epidermis
• mostly cluster round blood vessels
• antigen presenting cells mostly visible in prickle cell layer
• when these cells are stimulated (when something is presented to them), they migrate down into the dermis to find the lymphatics and go to the lymph nodes

Question 14

Name 5 appendages within the skin

Answer 14

1. Sebaceous glands
2. Hair follicles
3. Eccrine glands
4. Apocrine glands
5. Arrector pilli

Question 15

What do sebaceous glands do?

Answer 15

-secrete sebum
2 types:
-those associated with the hair follicle and secrete sebum into the hair follicle
-those that secrete directly onto the surface of the skin

Question 16

What do eccrine glands do?

Answer 16

twisty glands that extend all the way to the top of epidermis –> thermoregulation function, produce sweat

Question 17

What do apocrine glands do?

Answer 17

produce odour

Question 18

What are arrector pili muscles and what is their function?

Answer 18

• bundle of smooth muscle fibres
• insert at one end into the follicle sheath just below sebaceous gland and the other in the superficial dermis
• function is to make hair stand on end or be flat depending on temperature of person

Question 19

What is a pilosebceous unit?

Answer 19

made up of:

• sebaceous gland
• hair follicle
• arrector pilli muscle

Question 20

What are the 4 types of skin receptors?

Answer 20

1. Meissner corpuscles
2. Merkel cells
3. Pacinian corpuscles
4. Ruffini endings

Question 21

Where are meissner corpuscles found?

Answer 21

papillary (upper) dermis

Question 22

What is the function of meissners corpuscles?

Answer 22

fast adapting for detecting discriminatory touch and vibration

Question 23

What is the function of merkel cells?

Answer 23

slower adapting

discriminatory touch and pressure receptors

Question 24

What is the function of pacinian corpuscles?

Answer 24

large encapsulated sensory receptors responsive to pressure, coarse touch and rapid vibration

Question 25

Where are pacinian corpuscles found?

Answer 25

deep to the dermis, ligaments and joint capsules

Question 26

What is the lamella of a pacinian corpuscle composed of?

Answer 26

flattened schwann cells and endoneurial fibroblasts

Question 27

Where are merkel cells found?

Answer 27

in the basal layer of the epidermis (dermal-epidermal junction)

Question 28

Where are meissner’s corpuscles found?

Answer 28

found in the papillary dermis of the fingertips, soles of the feet, nipples, eyelids, lips and genitalia

Question 29

What is 1st degree burn?

Answer 29

• superficial burn that only effects the epidermis
• doesn’t extend into dermis or subcutaneous tissue
• quite painful but will resolve relatively quickly
• e.g sunburn

Question 30

What is 2nd degree burn?

Answer 30

• burn reaches dermis
• epidermis is lost
• inflamed and painful (pain level is determined by how deep it goes)

Question 31

Whats a third degree burn?

Answer 31

• full thickness burn
• goes through epidermis, dermis and subcutaneous tissue
• this might not be painful as all the nerve fibres and pain receptors could be damaged

Question 32

What is the papillary layer of the dermis made up of?

Answer 32

small blood vessels, lymph & nerves, fine collagen and elastic fibres

Question 33

What is the reticular layer of the dermis made up of?

Answer 33

vascular plexus
lymph
nerves & appendages
compact collagen fibres & thick elastic fibres

Question 34

What is a difference between thin and thick skin?

Answer 34

thin skin has hair follicles while thick skin is glabourous (non-hairy)

Question 35

Where is thick skin located in humans?

Answer 35

areas where there is lots of abrasion - fingertips, palms and soles of your feet

Question 36

What is the stratum basal layer (deepest layer) made of?

Answer 36

basal cells, merkel cells and melanocytes

Question 37

What is the stratum spinosum (prickle cell layer) made of?

Answer 37

made of keratinocytes, langerhans cell

Question 38

What is found in the stratum granulosum and stratum lucidum?

Answer 38

keratinocytes

Question 39

What is the function of langerhans cells?

Answer 39

they play an immunological role

Question 40

What are the 3 types of skin cancer and from which layer does each originate?

Answer 40

1. basal cell carcinoma –> basal cell layer, the lower part of the epidermis
2. squamous cell carcinoma –> upper outer epidermis
3. malignant melanoma

Question 41

What are warts?

Answer 41

• small non-cancerous growths that appear when you’re skin is infected with a virus from the HPV family
• they appear on fingers, palms, knuckles and knees

Question 42

except from hair follicles, which appendages are absent from thick skin?

Answer 42

sebaceous glands and apocrine sweat glands

Question 43

How are the arrector pilli muscles innervated?

Answer 43

• sympathetic nerve fibres

- cause arrector pili to contract and trap heat

Question 44

What is the dermis made up of?

Answer 44

connective tissue containing irregular bundles of collagen fibres plus networks of elastic fibres

Question 45

What is a blister?

Answer 45

fluid filled bumps under the epidermis. can fill with pus, blood or serum

Question 46

What is a dermatome?

Answer 46

an area of skin in which sensory nerves derive from a single spinal root

Question 47

What are the two types of cutaneous sensory receptors?

Answer 47

1. free nerve endings / unencapulated nerve endings / simple receptors
2. encapsulated nerve endings/ compound receptors

Question 48

What are free nerve endings?

Answer 48

-branching axons devoid of surrounding schwann cells

Question 49

What do merkel cell-neurite complexes do?

Answer 49

mechanoreceptors

Question 50

What do encapsulated nerve endings do?

Answer 50

mechanoreceptors

Question 51

Where are ruffini endings found and what is their function?

Answer 51

• located in superficial dermis

- stretching, tension shearing, deformation within joints and warmth