Skin

Question 1

What is the epidermis made up of?

Answer 1

Stratified squamous keratinising epithelium

Question 2

What are the 8 functions of skin?

Answer 2

protection
control of evaporation
sensation
absorption
manufacture of vitamin D
Thermoregulation
Storage and synthesis 
Excretion

Question 3

How does skin act as protection?

Answer 3

an anatomical barrier

langerhans cells in the skin are part of the adaptive immune system

Question 4

How does skin control evaporation?

Answer 4

Provides a relatively dry and semi-impermeable barrier to reduce fluid loss and prevent dehydration

Question 5

How does the skin show sensation?

Answer 5

Variety of nerve endings that respond to hot and cold

pressure , vibration , and tissue injury

Question 6

How does the skin absorb?

Answer 6

route of exposure for bioactive substances including medications

Question 7

What is the role of skin on the manufacture of vitamin D?

Answer 7

Vitamin D3 is synthesised when exposed to UV radiation mainly in the keratinocytes

Question 8

What is the role of skin in thermoregulation?

Answer 8

Sweat glands and dilated blood vessels aid heat loss while constricted vessels greatly reduce cutaneous blood flow and conserve heat

Question 9

What is the role of skin in storage and synthesis?

Answer 9

Acts as a storage centre for lipids and water

Question 10

What is the role of skin in excretion?

Answer 10

Sweat glands excrete perspiration through skin pores.

Question 11

What are the three primary layers of skin?

Answer 11

Epidermis
Dermis
Hypodermis

Question 12

What is the dermis made up of?

Answer 12

Dense irregular CT abundant in collagen

Question 13

What is the hypodermis made up of?

Answer 13

Adipose Tissue

Question 14

How many layers in thick skin?

Answer 14

5

Question 15

How many layers in thin skin?

Answer 15

4

Question 16

What are the 5 layers and which is only present in thick skin?

Answer 16

Stratum Coreum
Stratum Lucidum (thick skin only)
Stratum Granulosum
Stratum Spinosum
Stratum Basale

Question 17

Describe the stratum corneum?

Answer 17

Surface stratum- cells have no organelles-almost entirely composed of keratin

Question 18

Describe the Stratum lucidum?

Answer 18

Thick skin only and not always observed

Question 19

Describe Granulosum

Answer 19

2-3 layers of flattening cells ; granules contain a lipid rich scecretion, which acts as a water sealant

Question 20

Describe the stratum spinosum

Answer 20

2-8 layers: “prickle cells”; desmosomes and tonofilaments

Question 21

Describe the stratum basale

Answer 21

Deepest stratum; single layer of cubodial cells; hemidesmosomes bond layer to basal lamina and dermis. It is here that new cells are generated for the renewal of the epidermal layers of skin

lots of mitosis occurs here and the cuboidal cells are tightly packed together

Question 22

What are the four cells of the epidermis?

Answer 22

Keratincoytes
Melanocytes
Langerhans cells
Merkel cells

Question 23

What is the role of keratinocytes?

Answer 23

Make up the majority of cells - produce keratin

Question 24

What is the role of melanocytes?

Answer 24

Synthesis of melanin- skin colour is due to the production and breakdown

Question 25

What is the role of langerhans cells?

Answer 25

Antigen presenting cells

Question 26

What is the role of merkel cells?

Answer 26

sensitive mechanoreceptors essential for light touch sensation

Question 27

Describe the stages of keratinocyte development

Answer 27

Proliferation- DNA synthesis and mitosis Early differentiation- growth arrest, exit from cell cycle Intermediate differentiation- reinforcement of the cytoskeleton Late differentiation- expression of late markers Cornification- Cornified cell envelope- nuclear breakdown

Question 28

What are the two indistinct layer of the dermis?

Answer 28

Papillary layer(superficial) and reticular layer (deeper)

Question 29

How does skin become wrinkled?

Answer 29

With age collagen and elastin breaks down

Question 30

What is hypodermis also known as?

Answer 30

Subcutabneous tissue

Question 31

What is the role of the hypodermis?

Answer 31

Provides padding to the body and helps skin anchor to underlying tissue

Question 32

What appendages are there on the epidermis?

Answer 32

Sweat glands Hair follicles Sebaceous glands

Question 33

What are two sweat glands present on the epidermis and where are they located?

Answer 33

Merocine- highest density in palms and soles | Apocrine- axillary and anogenital regions

Question 34

What smooth muscle attaches to hair follicles?

Answer 34

Arrector pili

Question 35

What do sebaceous glands do?

Answer 35

Secrete sebum into base of hair follicle sebum softens & lubricates hair and skin prevents brittleness, slows water loss and kills bacteria

Question 36

What are hair follicles?

Answer 36

Hairs are elonagted keratinised structures that form within epidermal invaginations

Question 37

What is acne vulgaris?

Answer 37

An inflammatory disorder of the pilosebaceous unit occuring during adolescence.

Question 38

What are the three unencapuslated receptors?

Answer 38

Merkel cells Freee nerve endings Root hair plexuses

Question 39

What are the four encapsualted receptor?

Answer 39

Meissner corpuscles Pacinian corpuscles Krause end bulbs Ruffini corpuscles