Skin and Mucous Membranes

Question 1

Function of the skin

Answer 1

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

​

Question 2

Name the three layers of skin

Answer 2

Epidermis, dermis, subcutaneous layer

Question 3

How many layers does the epidermis have

Answer 3

4-5

Question 4

Structures associated with skin

Answer 4

Nails
Sweat glands
Sebaceous glands
Hair follicles

Question 5

Function of mucous membranes

Answer 5

Protective​
Oral cavity, nasal cavity, oesophagus​
Secretory​
Stomach​
Absorptive​
Entire small intestinal​
Sensation

Question 6

Lamina propria

Answer 6

The supportive areolar (loose fibrous connective tissue) layer found immediately beneath the mucosal epithelium and its basement membrane​

​

Question 7

Functions of the oral mucosa

Answer 7

Protection – barrier to micro-organism​

Sensation – receptors that respond to touch, taste, pain etc​

Secretion – maintains a moist surface ; salivary glands​

Permeability and absorption. A feature utilized in drug delivery.

Question 8

What is the structure of the epidermis

Answer 8

Stratified squamous epithelium
No blood vessels

Question 9

Where is keratin found

Answer 9

In the outer layers of epidermis

Question 10

Where is the stratum lucidum found

Answer 10

Only found in thick skin on heels/palms of hands etc
Not present in mucousa

Question 11

What are Langerhan’s cells

Answer 11

Antigen presenting cells which take foreign antibodies and presents them to the immune system/phagocytes for destruction

Question 12

What cells are present in the epidermis

Answer 12

Keratinocytes (95% of epidermal cells)
Langerhans cells
Melanocytes (produce melanin)
Merkel cells (sensory receptors)

Question 13

What are desmosomes and hemidesmosomes

Answer 13

Epithelial cell attachment:

Desmosomes found between epithelial cells. They are made up of different fibres such as keratin. Referred to as prickle cells due to appearance.

Hemidesmosomes found between basal cells and basement lamina

Question 14

How can we tell thick and thin skin apart

Answer 14

Stratum lucidum is only present in thick skin

Question 15

What is the dermis

Answer 15

Strong flexible connective tissue layer rich in collagen and elastic fibres

Question 16

What can be found within the dermis

Answer 16

-Fibroblasts​

-Macrophages​

-A few adipocytes​

-Nerve endings​

-Blood vessels​

-Glands​

-Smooth muscle (some areas)​

-Lymphatics​

-Hair follicles​​

Question 17

What layers are present within the dermis

Answer 17

Papillary layer - projects into intervals between the epidermal ridges. richly supplied with capillaries and nerve endings

Reticular layer - dense connective tissue and fibre components

**Reti ridges are the most important part of this interphase as they help hold each layer together

Question 18

Skin diseases/conditions

Answer 18

Psoriasis- autoimmune disease accelerated turnover of epithelial cells, usually 28-30 in psoriasis its only 7 days rarely affects oral cavity might have lesions on tongue. Patients with psoriasis may be taking steroids so should be aware​

Acne - shouldn’t be of concern as a dentist however some medication could be involved

Pemphigus - Protein forms desmosomes. (Desmoglein) weakens attachment of epithelial cells to each other allowing spaces to form which fill with fluid causing blisters which rupture quicky and leave ulcerated areas, loss of water, without treatment in extreme cases can cause death.​

Vitiligo - Loss of skin pigment (melanocytes affected)

Skin cancer:
-Squamous cell carcinoma
-Basal cell carcinoma
Keratinocytes in the epidermis grow out of control to form a tumour. Can occur on any part of your body (usually parts exposed to sunlight) appears scaly or crusty with red infammed base.

Malignant melanomas (5th most common cancer in the uk)

Question 19

What are mucous membranes

Answer 19

Specialized epithelial lining which produces 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 20

Functions of mucous membranes

Answer 20

-protective (oral/nasal cavity)
-secretory (stomach)
-absorptive (small intestine)
-sensation

Question 21

What are the names of the layers in a mucous membrane

Answer 21

Epithelium
Lamina propria (mucosea)

Question 22

What is the lamina propria

Answer 22

The supportive areolar (loose fibrous connective tissue) layer found immediately beneath the mucosal epithelium and its basement membrane​

Question 23

Structure of the lamina propria mucosea

Answer 23

Cells​:
Fibroblasts​
Immune cells​
Virtually lacking adipocytes​

Extracellular matrix :
Collagen
Elastin fibres

**The epithelium and the lamina propria mucosae together constitute the mucosa

Question 24

Where can the mucosa be found

Answer 24

Oesophagus

Trachea - Composed of a ciliated, pseudostratified epithelium and an elastic, fibre-rich lamina propria​

Small intestine (absorptive epithelium)

Question 25

Functions of the oral mucosa

Answer 25

Like skin, the main function of oral mucosa is protection. The oral cavity contains a vast number of various pathogens and is also exposed to daily sources of trauma, whether acids, chemicals, food and smoke. A good intact healthy mucosa is essential for maintain oral health. As a person gets older the oral mucosa becomes thinner and this barrier function is diminished. This may one of the reasons why the elderly are more prone to developing oral cancer then in younger age groups.​ Sensation: the oral mucosa contains receptors for all types of sensations in addition to taste which is only present in the oral cavity.​ Secretion: oral mucosa also contains minor salivary glands which maintain a moist surface essential for oral health and function.​ Permeability and absorption: like skin, oral mucosa has the ability to absorb substances which can be utilised in drug delivery. Medications for use in cardiovascular disease particularly for angina can be delivered as sublingual tablets or buccal spray for ease of use and rapid action.​

Question 26

Structure of the oral mucosa

Answer 26

Epithelium - Stratified squamous epithelium Lamina propria Gross types: ​ Lining- buccal mucosa, soft palate​ Masticatory- hard palate​ Gustatory (specialized type)-tongue​ Microscopic:​ non-keratinised​ keratinised orthokeratosis or parakeratosis​

Question 27

Keratin within the oral mucosa

Answer 27

Keratin obscures colour of underlying blood vessels​ Non keratinised epithelium - (inside cheeks, under tongue and soft palate) is a deeper red as the lack of keratin allows underlying tissues to show through ​ Ability to store glycogen – paler white cells​

Question 28

A condition which affects the skin and mucous membranes

Answer 28

Lichen planus (autoimmune)

Question 29

What is cystic fibrosis

Answer 29

An inherited autosomal recessive disease of ion transport ​ Abnormality in chloride channel protein (CFTR)​ Abnormal viscous secretions​ Affects epithelial lining of the respiratory, gastrointestinal and reproductive tracts​ Salivary glands may also be affected​