Structure and Function of the Skin

Question 1

What structures are found of the epidermis of the skin?

Answer 1

avascular epithelium which undergoes proliferation and synthesises keratin

Question 2

Components of the dermis

Answer 2

blood vessels, lymphatics, cutaneous nerves

collagen and elastic present but not replaced with age

Question 3

Components of the hypodermis

Answer 3

blood vessels, nerves, lymphatics
adipose tissue
skin ligaments

Question 4

What happens when the skin is burned?

Answer 4

There is a loss of the skin barrier function which can result in dangerous fluid loss and infection

Question 5

What type of epithelium is found at the epidermis?

Answer 5

Stratified squamous keratinised epithelium

Question 6

What is the deepest layer of the epidermis?

Answer 6

Stratum basale

Question 7

What is the function of hemidesmosomes in the stratum basale?

Answer 7

Anchors basal cells to basal lamina

Question 8

What attaches the dermis to the basal lamina of stratum basale?

Answer 8

Collagen VII

Question 9

What is the medical term for blistering?

Answer 9

Dystrophic epidermolysis bullosa

Question 10

What changes during blistering?

Answer 10

Collagen VII is mutated

Question 11

What is found at the stratum spinosum?

Answer 11

Intermediate filaments K1/K10 expressed
Desmosomes link cell to cell
Hemidesmosomes which link basal cells with basement membrane

Question 12

What regulates keratin in skin?

Answer 12

Differentiation programme regulates keratin expression pattern

Question 13

Where is filaggrin found?

Answer 13

Keratohyaline granules in S.granulosum

Question 14

Uses of filaggrin and its precursor profilaggrin

Answer 14

Maintain optimal skin barrier
Aids keratin filament aggregation
Inhibits water loss

Question 15

What can mutations of filaggrin cause?

Answer 15

keratinisation disorders
eczema
null mutations associated with asthma

Question 16

Where are melanocytes found?

Answer 16

Basal layer of epidermis

Question 17

What is the function of melanocytes?

Answer 17

Release brown pigment melanin

Question 18

What does melanin do?

Answer 18

Absorbs UV-B and prevents DNA damage to underlying cells of hypodermis

Question 19

What is melanoma?

Answer 19

Tumor of melanocytes caused by exposure to UV radiation

Question 20

Where are melanocytes derived from?

Answer 20

neural crest cells that originate near the developing nervous system and spread into the embryo

Question 21

How are melanosomes developed and transferred to keratinocytes?

Answer 21

Melanosomes are specialised lysosomes which are synthesised in melanocytes and undergo exocytosis to be transferred to keratinocytes

Question 22

Where are Langerhan cells derived from?

Answer 22

Monocytes

Question 23

Where are most Langerhan cells found?

Answer 23

Stratum spinosum

Question 24

What is the antigen processing function of Langerhan cells?

Answer 24

Langerhan cells activated in skin, migrate to lymph nodes, capture, process and present antigens

Question 25

Explain virus degradation

Answer 25

Langerhan cells express Langerin which help degrade viruses in specialised endosomes called Birbeck granules

Question 26

Where is the dermo-epidermal junction and what is its function?

Answer 26

Found in the dermis and is complex to prevent shearing. Papillae flatten with age

Question 27

Where is the papillary dermis found and what is it comprised of?

Answer 27

Found superficial to the reticular dermis comprised of fine collagen fibres, elastic fibres, small blood vessels and nerves

Question 28

What does the hypodermis support?

Answer 28

Deepest part of hair follicles Eccrine/merocine and apocrine sweat glands Site of vitamin D production

Question 29

Composition of eccrine sweat glands

Answer 29

Simple coiled and tubular, secrete a watery fluid. Found in dermis and superficial fascia but ducts open onto the surface of the skin

Question 30

What controls eccrine sweat glands?

Answer 30

Sympathetic nervous system- important in thermoregulation and as a response to fear

Question 31

Properties of apocrine sweat glands?

Answer 31

Open into hair follicles in axillary and genital region and secrete milky fluid containing pheromones

Question 32

Where does the hair shaft grow from and what is it composed of?

Answer 32

Grows from the hair bulb and is composed of keratin, associated with sebaceous glands that open into the follicle and secrete sebum

Question 33

Describe how goose bumps are produced?

Answer 33

Arrector pili contracts smooth muscle attached to the papillary dermis and the sheath of the follicle which pulls the hair upright- controlled by sympathetic NS

Question 34

What forms a pilosebaceous unit?

Answer 34

hair follicle, sebaceous gland, hair shaft and arrector pilli

Question 35

What are mammary glands?

Answer 35

modified apocrine sweat glands, lactation under hormonal control

Question 36

Properties of nails

Answer 36

Nail plate formed from keratin | Growth from nail root which passes deep into the dermis

Question 37

Properties of teeth

Answer 37

Enamel develops from epithelium | dentine, pulp and periodontal membrane is mesodermal

Question 38

What is the periodontal membrane?

Answer 38

Fibrous joint between teeth and skull

Question 39

What are pain receptors?

Answer 39

Free nerve endings | Nociceptors which responds when tissues are being damaged or close to being damaged

Question 40

Temperature receptors?

Answer 40

Free nerve endings | Separate receptors for cold and heat

Question 41

Touch organs?

Answer 41

Meissner's corpuscles- beneath the epidermis | Merkel cells for light touch- stratum basale

Question 42

Pressure organ?

Answer 42

Pacinian corpuscles - dermis

Question 43

Vibration organ?

Answer 43

Meissner's and Pacinian corpuscles- dermis

Question 44

What comprises the reticular epidermis?

Answer 44

Coarser collagen and elastic fibres and larger blood vessels and nerves

Question 45

What are the layers of the epidermis from top to bottom?

Answer 45

``` S. corneum S. Lucidum S. Granulosum S. Spinosum S. Basale ```