Wk 5: Integumentary (Skin)

Question 1

What kind of epithelia in skin

Answer 1

Skin consists of stratified squamous epithelium

Question 2

Metaplasia

Answer 2

The transformation of an epithelium into another type of epithelium

Question 3

Dysplasia

Answer 3

The enlargement of a tissue by proliferations of cells of an abnormal nature

Question 4

Adenocarcinoma

Answer 4

Malignant tumour formed from glandular structures in epithelial tissues

Question 5

5 functions of skin

Answer 5

1. Protection
2. Thermoregulation
3. Sensation
4. Secretion/excretion
5. Synthesis of Vit D

Question 6

What are the 3 layers of skin

Answer 6

1. Epidermis - outer
2. Dermis - middle
3. Hypodermis - inner (subcutaneous layer)

Question 7

What is the primary structure of the epidermis

Answer 7

Keratinocytes

Question 8

What is the primary structure of the dermis (2)

Answer 8

1. Connective tissue
2. Dermal capillaries

Question 9

What is the primary structure of hypodermis (2)

Answer 9

1. Loose connective tissue
2. Adipose tissue

Question 10

What other cells are found in the epidermis

Answer 10

• Keratinocytes
• Melanocytes
• Merkel cells
• Langerhans

Question 11

3 functions of epidermis

Answer 11

1. Maintenance of fluid & electrolyte balance
2. Protection from UV light (mediated through melanocytes)
3. Sensory (Merkel cells) & immune function (Langerhan cells)

Question 12

What are the 4 layers of epidermis

Answer 12

1. Stratum corneum
2. Stratum granulosum
3. Stratum spinosum
4. Stratum basale

Question 13

What is the thickest layer of the epidermis

Answer 13

The stratum corneum

Question 14

What does the stratum corneum contain

Answer 14

• Dead cells called corneocytes
• Keratin
  (Corneocytes dead in the sense that they have no nucleas but do contain large amounts of keratin, corneocytes are the final stage of differentiation of keratinocytes)

Question 15

What do the granules in the stratum granulosum contain & for what purpose

Answer 15

Granules contain glycolipids.
For waterproofing.

Question 16

What are the keratinocytes linked by in the stratum spinosum

Answer 16

Desmosomes

Question 17

What do cells in the stratum spinosum contain

Answer 17

Cells contain bundles of prekeratin

Question 18

What does the stratum basale consist of

Answer 18

• Stem cells
• Younger keratinocytes

Question 19

There is a 5th layer of the epidermis found only in thick skin, what is this called

Answer 19

Stratum lucidum

Question 20

Where are melanocytes found in the epidermis & what is their function

Answer 20

• Found in the stratum basale
• They scavenge free radicals to protect against UV (damage to nucleus = uncontrolled proliferation

Question 21

Where are merkel cells found in the epidermis & what is their function

Answer 21

• Found in the stratum basale
• Function as sensory receptors for touch

Question 22

Where are langerhans cells found in the epidermis & what is their function

Answer 22

• Mainly found in the stratum spinosum
• Function as a type of macrophage - engulf pathogens, become antigen presenting cells, release signalling molecules that attract cells of immune system to area of invading pathogen

Question 23

What is basal cell carcinoma derived from

Answer 23

Derived from basal keratinocytes

Question 24

What is squamous cell carcinoma derived from

Answer 24

Derived from mature differentiated keratinocytes

Question 25

What is malignant melanoma derived from

Answer 25

Derived from melanocytes - uncontrolled proliferation

Question 26

What are the 2 layers of the dermis

Answer 26

1. Papillary dermis 2. Reticular dermis

Question 27

What does the papillary dermis contain & what is the function of these

Answer 27

* Includes the dermal papilla which project into the epidermis * These increase contact area preventing epidermal detachment

Question 28

Components of the dermis

Answer 28

* Connective tissue * With fibroblasts * Macrophages * In a collagen & elastin matrix * Large numbers of capillaries, nerve endings & lymphatics

Question 29

What are the specialised structures found in the dermis

Answer 29

1. Sweat glands 2. Apocrine glands 3. Sebaceous glands 4. Hair follicles

Question 30

What are the two types of sweat glands

Answer 30

1. Eccrine glands 2. Apocrine glands

Question 31

Where are eccrine glands found

Answer 31

Almost everywhere

Question 32

Where are apocrine glands found

Answer 32

Mainly in axilla & anogenital area

Question 33

What's the difference between eccrine & apocrine glands

Answer 33

* Secretions in apocrine glands contain more fat & protein than eccrine glands - bacterial breakdown of this is the basis of body odour * Secreted onto hair follicles, not skin

Question 34

What do sebaceous glands secrete

Answer 34

Oily substance called sebum

Question 35

What are sebaceous glands activated by

Answer 35

Androgens

Question 36

Functions of the hypodermis

Answer 36

1. Connects skin to underlying fascia of bones & muscles 2. Insulator 3. Shock absorber 4. Protection

Question 37

Structure of hypodermis

Answer 37

* Well vascularised, loose, areolar connective tissue & adipose tissue