Skin

Question 1

Functions of skin

Answer 1

Protection against chemical, thermal and mechanical insults, bacterial and fungal invasion, dessication and uv light
Has sensors for touch, pressure, pain and temperature
Thermoregulation
Production of vitamin D3
Significant energy store

Question 2

Layers of skin

Answer 2

Epidermis, dermis and hypodermis

Question 3

Epidermis

Answer 3

Composed of keratinised stratified squamous epithelium

Question 4

Dermis

Answer 4

Composed of a layer of fibrocollageous and elastic connective tissue that contains blood vessels, nerves and sensory receptors

Question 5

Hypodermis

Answer 5

Composed mainly of adipose tissue
Varies in thickness
Scattered septa made up of bundles of collagen

Question 6

What is the function of septa in the hypodermis

Answer 6

Help anchor the skin to the underlying deep fascia

Question 7

Layers of the epidermis

Answer 7

Stratum basale, stratum spinosum, stratum granulosum and stratum corneum

Question 8

What is a possible 5th layer of the epidermis

Answer 8

Stratum lucidum

Question 9

Statum basale

Answer 9

Single layer of cells sitting on basal lamina

Stem cells for the epidermis

Question 10

Stratum spinosum

Answer 10

5 cells thick

Many desmosomes attaching cells to each other

Question 11

Stratum granulosum

Answer 11

Cells aquire large numbers of dense cytoplasmic granules
Cells produce lamellar bodies
Further up the layer, the cells gain more keratin and organelles are being progressively lost

Question 12

Stratum corneum

Answer 12

Composed of dead squamous cells packed with keratin in a specialised matrix

Question 13

What are the dense cytoplasmic granules called

Answer 13

Keratohyalin granules

Question 14

What do keratohyalin granules contain

Answer 14

Profilaggrin

Question 15

What does profilaggrin promote

Answer 15

The aggregation of cytokeratin intermediate filaments

Question 16

Aggregations of cytokeratin intermediate filiments known as

Answer 16

Keratin

Question 17

Stratum lucidum

Answer 17

Thin layer found only in thick skin consisting of dead cells with abundant keratin

Question 18

Non-keratinising cells of epidermis

Answer 18

Melanocytes, langerhans’ cells and merkel cells

Question 19

Melanocytes

Answer 19

Many long cell processes

Produce melanin

Question 20

What does melanin complex with and what does it form

Answer 20

Proteins to form melanoprotiens

Question 21

What are melanoprotiens passed to and through

Answer 21

Keratinocytes and through granules called melanosomes

Question 22

Two forms of melanin

Answer 22

Pheomelanin and eumelanin

Question 23

Langerhans’ cells

Answer 23

Resident immune cells
Act as antigen presenting cells
Have a network of cell processes to increase surface area
Numbers increase during inflammatory conditions
Invade the skin from the blood stream

Question 24

Merkel cells

Answer 24

Touch receptors found in basal layer of epidermis

Associated with a nerve ending and form low threshold/slowly adapting receptors

Question 25

Two layers of dermis

Answer 25

Papillary dermis - superficial | Reticular dermis - deep

Question 26

Papillary dermis

Answer 26

Forms dermal papillae which project upwards and interdigitate with downwards projections of the epidermis called rete ridges Consists of bundles of fine collagen and elastic tissue

Question 27

Reticular dermis

Answer 27

Forms dense irregular connective tissue with thick bundles of collagen fibres and elastic fibres embedded in small amounts of extracellular material

Question 28

Other name for hypodermis

Answer 28

Subcutis

Question 29

Epidermal skin appendages

Answer 29

Hair follicles, sebacous glands and sweat glands

Question 30

Hair follicles

Answer 30

Tubular structure extending down through the epi into the dermis and hypo Has 5 layers At the bottom extension = hair bulb Concave region = dermal hair papilla

Question 31

Sebaceous gland

Answer 31

Usually associated with hair follicle Produce sebum Utilise holocrine secretion

Question 32

Arrector pili muscles

Answer 32

Associated with hair follicle Small band of muscle Runs obliquely upwards and ends in upper part of dermis Innervated by sympathetic nervous system

Question 33

Sweat glands

Answer 33

2 types - eccrine and apocrine Coiled tube located near junction of dermis and hypo Made up of secretory and duct segements

Question 34

Secretory segment of sweat gland

Answer 34

Coiled tubular gland | Pseudostratified epithelium

Question 35

Duct segment of sweat gland

Answer 35

Initially coiled but then straightens | Stratified cuboidal epithelium

Question 36

Apocrine sweat glands

Answer 36

``` Restricted to axillae, genitalia and areolae of the nipple Produce a milky fluid Ducts typically end on hair follicles Secretory sections have large lumen Utilise merocrine secretion ```

Question 37

Nails

Answer 37

Hard plates of keratin Formed by cells of the nail matrix Nail bed is analogus and continuous with epidermis

Question 38

Visible half moon portion of nail matrix

Answer 38

Lunula

Question 39

Sensory receptors of skin can be classified by

Answer 39

Free nerve endings or encapsulated nerve endings

Question 40

Free nerve endings form

Answer 40

Meissner's corpusce

Question 41

Encapsulated nerve endings from

Answer 41

Pacinian corpuscle