Skin and mucous membranes

Question 1

Functions of the skin

Answer 1

Protection (pathogens, UV, injury), thermoregulation (blood vessels, hair, sweat), water regulation, sensation, absorption, storage and synthesis (vit D)

Question 2

Layers of the skin

Answer 2

epidermis, dermis, subcutis/ subcutaneous layer

Question 3

What are sebaceous glands?

Answer 3

Found in hair follicles, secrete sebum

Question 4

Basic structure of the epidermis

Answer 4

Keratinised stratified, squamous epithelium. No capillaries and no nerve endings.

Question 5

Layers of the epidermis

Answer 5

Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum in thick skin, stratum corneum.

Question 6

What is stratum basale?

Answer 6

Basal cell layer. One cell remains and acts as a stem cell that divides to form epithelial cells.

Question 7

What is stratum spinosum?

Answer 7

Prickle cell layer. Cells have desmosomes

Question 8

Desmosomes function

Answer 8

attach epithelial cells to each other

Question 9

What is stratum granulosum?

Answer 9

Granular cell layer. Cells become smaller and fatter and accumulate keratohyaline granules. The nucleus degenerates and disappears.

Question 10

What is stratum corneum?

Answer 10

Keratin

Question 11

Which epidermis cell layer is only visible in thick skin?

Answer 11

Stratum lucidum (clear cell layer). Between stratum granulosum and stratum corneum. Pale waxy appearance with no nucleus.

Question 12

Name of cells that produce keratin

Answer 12

Keratinocytes (95% of epidermal cells)

Question 13

Name and features of antigen presenting cells found in the epidermis

Answer 13

Langerhans cells. Have dendritic cell projections from cell body

Question 14

Name and location of sensory receptors

Answer 14

Merkel cells found underneath basal cell layer

Question 15

Function and location of melanocytes

Answer 15

produce melanin and found in stratum basale

Question 16

How to identify melanocytes in specimen

Answer 16

Tend to be paler in colour. No desmosomes. Shrinking of cells gives appearance of clear space around melanocytes

Question 17

Difference between thick and thin skin

Answer 17

Thick skin has stratum lucidum, thicker stratum corneum, more prominent stratum granulosum (more keratin granules).

Question 18

Location of thick skin

Answer 18

Palms of hands and soles of feet. Areas of fingers (e.g. where pen is held)

Question 19

Dermis description

Answer 19

strong flexible connective tissue layer rich in collagen (mostly) and elastic fibres

Question 20

location of dermis

Answer 20

beneath epithelium/epidermis

Question 21

What are fibroblasts?

Answer 21

Thin spindle shaped cells that produce collagen. Found in dermis

Question 22

Contents of dermis

Answer 22

fibroblasts, macrophages, adipocytes, nerve endings, blood vessels, smooth muscle, lymphatic vessels, glands, hair follicles

Question 23

2 layers of dermis

Answer 23

Papillary layer and reticular layer

Question 24

What are rete / epidermal ridges?

Answer 24

Papillary layer has upward projections while epithelial layers of epidermis have downward projections. Hold epidermis and dermis tightly together.

Question 25

Description of papillary layer

Answer 25

Has rete ridges. Richly supplied with capillaries and nerve endings

Question 26

Description of reticular layer

Answer 26

Dense connective tissue containing blood vessels and lots of fibres

Question 27

Causes of acne

Answer 27

overproduction of sebum from sebaceous glands, infections from bacteria on skin, hormones, diet (fat), smoking

Question 28

What is psoriasis?

Answer 28

Autoimmune condition that primarily affects skin

Question 29

Feature of psoriasis in oral cavity

Answer 29

lesion on tongue

Question 30

cause of psoriasis

Answer 30

rapid turnover of epidermis cells (7 instead of 28 days) which causes a thicker epidermis. Blood in underlying capillaries due to inflammation

Question 31

Signs of psoriasis

Answer 31

Red, scaly patches typically on scalp ad areas of friction (knees and elbows)

Question 32

What is Pemphigus vulgaris?

Answer 32

Autoimmune condition that affects skin and mucous membranes

Question 33

Sign of pemphigus vulgaris

Answer 33

Blisters on skin and oral cavity. May look like raw, painful areas of mouth due to blisters rupturing very quickly.

Question 34

How do blisters form in Pemphigus vulgaris?

Answer 34

Autoantibodies attack desmoglein (protein that forms desmosomes) which breaks up attachment of epithelial cells. Spaces form between epithelial cells which become filled with fluid - blisters.

Question 35

How do lesions impact the water regulating ability of the skin?

Answer 35

Loss of fluid can occur from lesions -> dehydrations

Question 36

What drug can be used to bring pemphigus vulgaris into reemission

Answer 36

corticosteroids

Question 37

What is vitiligo?

Answer 37

Autoimmune condition that causes loss of skin pigment - autoantibodies formed against melanocytes or melanocyte-stimulating hormone.

Question 38

two commonest skin cancers

Answer 38

squamous cell carcinoma (malignancy of epithelial cells), basal cell carcinoma

Question 39

What is skin cancer?

Answer 39

Uncontrolled growth of epithelial cells that creates lump that breaks down to create a crusty, scaly area of skin with a red, inflamed base

Question 40

One of most dangerous skin malignancy

Answer 40

Malignant melanomas

Question 41

risk factors for malignant melanomas

Answer 41

UV radiation, moles (collection of melanocytes), fair skin with freckles, sunburn, family history

Question 42

What are mucous membranes?

Answer 42

specialised epithelial lining which produced a lubricant fluid (mucous) containing mucin (sticky protein)

Question 43

Function of mucous membranes

Answer 43

defence mechanism, protective, secretory (stomach can produce gastric enzymes and acid), absorptive (small intestine), sensation

Question 44

Structure of mucous membranes

Answer 44

Contains 2 layers - epithelial and lamina propria (mucosae) separated by basement membrane

Question 45

What cell type makes up the epithelial layer in mucous membranes?

Answer 45

Stratified squamous epithelia

Question 46

What is the lamina propria?

Answer 46

A supportive areolar layer (loose fibrous CT) beneath the mucosal epithelium and its basement membrane.

Question 47

What makes up the lamina propria mucosae?

Answer 47

Cells (fibroblasts, immune cells, lymph nodules), extracellular matrix (ground substance, collagen, elastin fibres)

Question 48

Example: cells that make up the trachea

Answer 48

pseudostratified ciliated columnar epithelium and goblet cells. Lamina propria under epithelium

Question 49

Example: composition of small intestine

Answer 49

absorptive epithelium with a brush border, goblet cells that produce mucin, villi containing lots of lymphatics

Question 50

Functions of the oral mucosa

Answer 50

Protection, sensation (touch, pain, taste), secretion (salivary glands), permeability and absorption (rapid drug delivery)

Question 51

Composition of oral mucosa

Answer 51

stratified squamous epithelium, lamina propria

Question 52

3 types of mucous membrane in mouth

Answer 52

lining, masticatory, gustatory

Question 53

Structure and location of lining mucous membrane

Answer 53

non-keratinised stratified squamous epithelium. red tissue. Buccal, floor of mouth, soft palate

Question 54

Structure and location of masticatory mucous membrane lining

Answer 54

thick layer of keratin. present in areas of trauma from food - gingiva, hard palate and tongue

Question 55

Composition and location of gustatory mucous membrane

Answer 55

taste buds. tongue

Question 56

How can keratinised tissue be divided microscopically?

Answer 56

orthokeratosis (pure keratin, no nuclei) or parakeratosis (remains of nuclei - little dark dots)

Question 57

Congenital meaning

Answer 57

present from birth

Question 58

What is lichen planus?

Answer 58

A rash that can affect skin and mucous membranes. Painless or stinging/burning sensation

Question 59

Cause of cystic fibrosis

Answer 59

Autosomal recessive condition causes a mutation in CFTCR gene (cystic fibrosis transmembrane conductive regulator gene)

Question 60

Effects of cystic fibrosis

Answer 60

thick and stagnated mucous affects the epithelial lining of the respiratory, gastrointestinal and reproductive tracts, and salivary glands (prone to calcification and inflammation). Site for invasion of pathogens (respiratory tract infections)