Skin

Question 1

What are the 4 primary tissue types?

Answer 1

• Epithelium
• Connective tissue]
• Muscle
• Nerve

Question 2

What are epidermal cells termed as?

Answer 2

Keratinocytes

Question 3

What is the function of the epidermis?

Answer 3

Prevents water loss by evaporation

Question 4

What are the functions of the dermis?

Answer 4

• Reduces the risk of external injury
• Maintains the epidermis by its blood flow
• Permits body cooling
• Immune surveillance
• UV protection
• Energy storage
• Sensory information

Question 5

What does the epidermis consist of?

Answer 5

Epithelium which forms boundaries between internal and external compartments

Question 6

What does the dermis consist of?

Answer 6

Connective tissue which give structural support

Question 7

How can epithelial be described?

Answer 7

Stratified squamous keratinising epithelium

Question 8

What kind of origin does epidermis have?

Answer 8

Ectodermal origin

Question 9

What are the 4 types of epidermal cells?

Answer 9

• Keratinocytes
• Melanocytes
• Langerhans cells
• Merkel cells

Question 10

Describe keratinocytes.

Answer 10

• Most frequent
• Contain keratin
• Hard and resistant to abrasion
• Extrude lipids making it waterproof
• Constantly dividing

Question 11

What is the function of melanocytes?

Answer 11

Pigment formation and injection of melanin in the str. germinaticum

Question 12

What is the function of Langerhan cells?

Answer 12

Immune surveillance

Question 13

What is the function of Merkel cells?

Answer 13

Touch receptors

Question 14

What are the 5 layers of the epidermis from outside in?

Answer 14

• Stratum corneum
• Stratum lucidum
• Stratum granulosum
• Stratum spinosum
• Stratum basale

Question 15

Describe the stratum spinosum.

Answer 15

• Spinous layer
• Cells shrink post mortem and desmosomes create spines
• Little structural evidence of activity
• Preparative layer for keratinisation

Question 16

Describe the stratum granulosum.

Answer 16

• Presence of granules defines the layer

- Granules of keratohylain

Question 17

What 2 layers can be difficult distinguish?

Answer 17

Stratum corneum and Stratum lucidum

Question 18

Describe the stratum corneum.

Answer 18

• Conversion of keratohyalin to keratin
• Lots of disulphide linkages give strength
• No organelles
• Desmosomes bind cells
• Fortnightly turnover

Question 19

What is keratinisation?

Answer 19

Organic process whereby keratin is deposited in cells and these become horny as in dead skin, nails and hair

Question 20

How does epidermal thickness vary?

Answer 20

• Palms and soles of feet are thick skin

- Abdominal skin is thin

Question 21

What are the 2 layers of the dermis?

Answer 21

• Papillary layer

- Reticular layer

Question 22

Describe the papillary layer

Answer 22

• Loose connective tissue
• Cellular
• Irregular interface with epidermis
• Protective against pathogens
• Contains blood vessels and nerve endings

Question 23

Describe the reticular layer.

Answer 23

• Dense irregular connective tissue
• Collagen bundles in three planes
• Elastic fibres

Question 24

How does keratin originate?

Answer 24

Originates as lamellated granules in str. granulosum

Question 25

How is skin waterproofed?

Answer 25

- Keratin in cells waterproofs | - Intracellular spaces filled with lipid cement

Question 26

What is responsible for skin colour?

Answer 26

- Blood - Carotene - Melanin

Question 27

What does melanin do?

Answer 27

Protects us against UV

Question 28

Describe hair in relation to skin.

Answer 28

- Mainly for vanity but has a practical use in skin repair | - Derived from the epithelial layer

Question 29

Describe the origin of hair follicles.

Answer 29

- From epidermis in utero - Down growth of epithelial cells - Invasion of know of blood vessels - Growth of hair - Continuity with layers of epidermis

Question 30

What does a hair follicle consist of?

Answer 30

- Hair and sheath - Arrector pili muscles - Sebaceous glands

Question 31

Describe arrector pili muscles?

Answer 31

- Attached to follicle root and base epidermis - Follicle at angle - Hair straightens when muscle contracts

Question 32

Describe sebaceous glands?

Answer 32

- Between follicle and arrector pili muscle - Secretes sebum - Function uncertain

Question 33

What skin glands are there?

Answer 33

- Sebaceous- hair follicles - Apocrine sweat glands (BO) - Eccrine sweat glands

Question 34

Describe eccrine sweat glands.

Answer 34

- Simple tubular glands - Located in the dermis - Coiled secretory portion - Coiled and straight duct in dermis - Spiral channel in epidermis - Watery secretion - Thermoregulatory

Question 35

What is involved in thermoregulation/

Answer 35

- Sweat glands - Blood vessels - Hair (but not in human)

Question 36

What sensory endings are there in skin?

Answer 36

- Meissener's corpuscles: light touch in fingertips - Paccinian corpuscles: vibration and pressure - Pain receptors - Thermoreceptors