Week 4 Skin, epithelium & connective tissue

Question 1

3 Layers of skin

Answer 1

1. Epidermis - stratified epithelium
2. Dermis - connective tissue
3. Subcutis - fat

Question 2

4 Layers of epidermis

Answer 2

1. Stratum Corneum
2. Stratum Granulosum
3. Stratum Spinosum
4. Stratum Basale

Question 3

3 Importance of the dermo-epidermal junction (DEJ)

Answer 3

1. Adhesion
2. Cellular migration
3. Cellular signalling

Question 4

What are the 2 major protein fibres in dermis? What are their main functions?

Answer 4

1. Collagen - tensile strength

2. Elastin - Elasticity

Question 5

Main functions of the subcutis layer

Answer 5

1. Energy reserve (adipose tissue)
2. Cushion effect
3. Insulation

Question 6

4 Classes of pilosebaceous unit and their locations

Answer 6

1. Terminal - scalp, beard
2. Vellus - majority of skin
3. Apopilosebaceous - axilla, groin
4. Sebaceous - face, chest, back

Question 7

3 phases of cyclical hair growth

Answer 7

1. Anagen - growing
2. Catagen - regressing
3. Telogen - resting (hair shedding occurs)

Question 8

What is the type of skin that doesn’t contain any pilosebaceous unit? Characteristics? Example?

Answer 8

Glabrous skin

• non-hair bearing
• lack of hair follicles and sebaceous gland
  e. g. palm, sole

Question 9

Characteristics of sebaceous gland

Answer 9

1. Large and well-developed in fetus
2. size rapidly reduced after birth
3. Regain of function at puberty

Question 10

2 Types of sweat glands

Answer 10

1. Eccrine - entire body surface

2. Apocrine - axilla, genitalia, mammary areas

Question 11

2 Types of perspiration

Answer 11

1. Insensible perspiration - passive evaporation from skin surface
2. Active sweating - mainly through eccrine glands

Question 12

4 Functions of nail

Answer 12

1. Mechanical protection
2. Enhance sensory discrimination
3. Dexterity (scratching/grooming)
4. Cosmetic accessory

Question 13

What are the skin appendages?

Answer 13

1. Hair
2. Nail
3. Adnexal structures - pilosebaceous unit, eccrine glands, apocrine glands

Question 14

4 Components of the pilosebaceous unit

Answer 14

1. Hair shaft
2. Hair follicle
3. Sebaceous gland
4. Arrector pili muscle

Question 15

Origin of skin (development)

Answer 15

Ectoderm: nervous system, epidermis
Mesoderm: dermis, skin appendages

Question 16

7 Functions of skin

Answer 16

1. Mechanical barrier
2. UV protection
3. Thermoregulation
4. IMmunity
5. Sensation - innate + adaptive
6. Endocrine - production of vitamin D
7. Communication

Question 17

6 Functions of epithelium

Answer 17

1. Cover surfaces and cavities of body2
2. Protection
3. Secretion
4. Absorption (e.g. digestive epithelium)
5. Transport
6. Sensory

Question 18

5 Common properties of epithelium

Answer 18

1. Avascular
2. Little/no intercellular matrix
3. Junctional structures
4. Rest on basement membrane
5. Contains cytokeratin

Question 19

What is the basement membrane made up of?

Answer 19

Basal lamina (type IV collagen) + Reticular lamina (type I collagen)

Question 20

2 types of special epithelia

Answer 20

1. Pseudostratified ciliated columnar epithelium with globet cells (in respiratory epithelium)
2. Transitional epithelium - allow changes in shape
   (e. g. in bladder)

Question 21

Special types of simple epithelium (single layer)

Answer 21

1. Mesothelium: lining of pleural and abdominal cavities, surfaces of internal organs
2. Endothelium: lining of all blood vessels and lymphatics

Question 22

Specializations at different surfaces of epithelium

Answer 22

1. Apical surface: microvilli / cilia
2. Lateral surface: junctional complex
3. Basal surface: adhesion to basal lamina/anchoring junction(actin or hemidesmosomes)/basal membrane infolding (interdigitation)

Question 23

What is a single cell gland? Where is it found?

Answer 23

Goblet cell

found in tracheal and intestinal epithelium

Question 24

3 Modes of secretion

Answer 24

1. Merocrine
2. Apocrine
3. Holocrine

Question 25

5 types of exocrine glands

Answer 25

1. Simple tubular 2. Simple coiled tubular 3. Simple branched tubular 4. Simple branched acinar 5. Compound tubuloacinar

Question 26

5 Main functions of connective tissue

Answer 26

1. Support epithelium 2. Protection 3. Connect tissues/organs 4. Tissue repair 5. Extracellular matrix is important in regulating behaviour in cells

Question 27

What is the extracellular matrix (ECM) of connective tissue composed of?

Answer 27

1. Ground substance | 2. Fibrous components

Question 28

What makes up the gel-like ground substance of connective tissue?

Answer 28

1. Proteoglycans | 2. Glycoproteins

Question 29

3 Types of fibers in ECM of connective tissue

Answer 29

1. Collagen fibers (type I collagen) 2. Elastic fibers (elastin) 3. Reticular fibers (type III collagen)

Question 30

3 Broad types of connective tissue

Answer 30

1. Connective tissue proper 2. Specialized connective tissue (e.g. adipose tissue, blood, lymphatics, cartilage, bone) 3. Embryonic connective tissue

Question 31

3 criteria for classification of connective tissue`

Answer 31

``` 1. Abundance of fibers: loose/dense 2. Arrangement of fibers: irregular/regular 3. Nature of fibers: white (collagen) / yellow (elastin) ```

Question 32

6 Common types of cells found in connective tissue and their functions

Answer 32

1. Fibroblasts: synthesize fibres and ground substance 2. Macrophages: phagocytosis 3. Plasma cells: antibody production 4. Mast cells: release histamine 5. Fat cells: storage of fat 6. Leukocytes: defense

Question 33

2 types of adipose tissue

Answer 33

1. Unilocular adipose tissue (white) - 1 large fat vacuole, common in adults 2. Multiocular adipose tissue (brown) - several fat vacuoles in each cell, important for baby

Question 34

3 types of specialized connective tissues

Answer 34

1. Cartilage and bone 2. Adipose 3. Haemopoietic tissue