Skin

Question 1

What is the integumentary system?

Answer 1

Comprises of skin and its appendages
Includes hair, feathers, hooves, nails
Protects the body from damage

Question 2

What are the functions of skin?

Answer 2

• Protection - from pathogens, UV, injury
• Thermoregulation - via blood vessels, sweat, hair
• Water regulation - prevents moisture loss
• Sensation - touch, temperature, pain
• Absorption
• Storage and synthesis - Vitamin D, fat, glucose, water, salt

Question 3

What are the layers in skin?

Answer 3

Epidermis
Dermis
Subcutaneous layer

Question 4

What are some of the structures associated with skin?

Answer 4

Nails, hair follicles, sweat glands, sebaceous glands

Question 5

Describe the structure of and layers of the epidermis

Answer 5

• Stratified squamous epithelium (layered, flat scale-like cells)
• No blood vessels
• 4-5 layers (Stratum basalae, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum)

Question 6

Which layer of the epidermis contains desmosomes?

Answer 6

Stratum spinosum

Question 7

What are the 5 layers of epidermis?

Answer 7

Stratum basalae, stratum spinosum, stratum granulosum, stratum lucidum and stratum corneum

Question 8

Describe what happens to cells as they migrate from the basal layer to the stratum corneum

Answer 8

The nucleus shrinks and cells begin to flatten and become keratinised

Question 9

Which type of skin has a stratum lucidum layer?

Answer 9

Thick skin

Question 10

What is the function of melanocytes?

Answer 10

Make melanin to give skin pigment and colour

Question 11

What are Merkel cells?

Answer 11

Sensory receptors

Question 12

What are Langerhans cells?

Answer 12

Antigen presenting cells (APCs)

Long, spine-like projections

Question 13

What is the difference between thick skin and thin skin?

Answer 13

• Presence of the stratum lucidum layer in thick skin (absent in thin skin)
• Thick skin has thicker keratin layer/stratum corneum
• Thick skin joined by hemidesmosomes rather than desmosomes

Question 14

Where would you find thick skin?

Answer 14

Palms of hands and soles of feet

Question 15

Describe the dermis layer of skin

Answer 15

Under the epidermis
Contains: fibroblasts, macrophages, adipocytes, nerve endings, blood vessels, glands, smooth muscle, lymphatics, hair follicles

Question 16

Which layer of skin contains hair follicles?

Answer 16

Dermis

Question 17

What do fibroblasts form?

Answer 17

Collagen fibres

Question 18

What are the 2 layers of the dermis?

Answer 18

Papillary layer

Reticular layer

Question 19

Describe the papillary layer of the dermis

Answer 19

Projects into intervals between the epidermis ridges. Richly supplied with capillaries and nerve endings

Question 20

Describe the reticular layer of the dermis

Answer 20

Dense connective tissue and fibre components

Question 21

What is acne?

Answer 21

• Infection that occurs on the skin during puberty mostly caused by hormones
• Bacteria, diet, smoking can also cause acne

Question 22

What is psoriasis?

Answer 22

• Chronic skin condition
• Auto-immune
• Usually affects knees, elbows, scalp
• Increased epithelial cell division
• Red scaly skin
• Cells divide quickly: thicker skin and more blood vessels -> causes redness

Question 23

What is pemphigus?

Answer 23

• Autoimmune condition
• Antibodies target protein in desmosomes
• Cells start to separate
• Fluid accumulates in spaces between cells
• This ruptures and causes large eroded spaces
• Causes loss of fluid
• Can affect skin and mouth

Question 24

What is vitiligo?

Answer 24

• Lack of pigmentation

- Loss of melanocytes in the skin

Question 25

Name 2 types of skin cancer

Answer 25

Squamous cell carinoma

Basal cell carcinoma

Question 26

What happens in skin cancer?

Answer 26

Keratinocytes in epidermis grow out of control to form a tumour
Can occur in any part of the body (commonly areas exposed to sun)
Appears as scaly or crusty area of skin, with a red and inflamed base

Question 27

What are risk factors for malignant melanomas?

Answer 27

Moles, UV exposure, fair skin with freckles, sunburn, family history

Question 28

What are mucous membranes?

Answer 28

Specialised epithelial lining which produce a lubricating fluid containing the sticky protein mucin which traps microbes and dirt particles and protects any body structure which is continuous with the external environment

Question 29

What is the structure of mucous mebranes?

Answer 29

• Epithelium
• Basement membrane (has hemidesmosomes)
• Lamina propria

Question 30

Describe the lamina propria layer in mucous membranes

Answer 30

• Contains fibroblasts, immune cells

- ECM: collagen, elastin fibres

Question 31

What type of epithelium is found in the trachea?

Answer 31

Ciliated, pseudostratified epithelium and an elastic, fibre-rich lamina propria

Question 32

What are goblet cells?

Answer 32

Glands (made of one cell) that produce mucous

Question 33

Describe oral mucosa

Answer 33

• Stratified squamous epithelium
• Lamina propria
• Lining (buccal mucosa, soft palate), gustatory (tongue dorsum) and masticatory (hard palate, gingiva)
• Masticatory = parakeratinised, gustatory = keratinise, lining = non-keratinised

Question 34

What are the functions of oral mucosa?

Answer 34

• Protection: barrier to microorganisms
• Sensation: receptors that respond to touch, taste, pain, etc
• Secretion: maintains a moist surface, salivary glands
• Permeability and absorption

Question 35

What is lichen planus?

Answer 35

• Autoimmune condition
• Antibodies against epithelium
• Can affect both skin and mucous membranes
• Shows as white patches
• Sometimes painless, sometimes burning or itchy

Question 36

What is cystic fibrosis?

Answer 36

• An inherited disorder of ion transport (gene that codes Cl- channel is mutated)
• Abnormal viscous secretions (lots of mucous)
• Affects epithelial lining of respiratory, G.I., and reproductive tracts
• Salivary glands may also be affected