L19 : Skin structure

Question 1

What are the 3 layers of the skin?

Answer 1

• Epidermis
• Dermins
• Hypodermis

Question 2

State the characteristics and functions of Hypodermis

Answer 2

Characteristics

• adipose tissue, LCT
• also known as sub-cutaneous layer

Function

• Energy store
• Insulator
• shock absorber

Question 3

State the characteristics and functions of Dermis

Answer 3

C :

• known as corium
• consist of papillary, reticular and dermal papillae

F :

• thermoregulation
• senses

Question 4

State the characteristics and functions of Epidermis

Answer 4

C :

• 4 layers if thin skin
• 5 layers if thick skin
• adheren junctions
• no blood vessels

F :

• prevents water loss
• protection againts pathogen ingress

Question 5

What are the 4/5 layers of the skin?

Answer 5

• stratum corneum
• stratum lucidum
• stratum granulosum
• stratum spinosum
• stratum basale

Question 6

Where is stratum lucidum found?

Answer 6

palms and soles of feet

Question 7

Describe the charactersitics of stratum granulosum, stratum spinosum and stratum basal

Answer 7

SG :

• stratified squamous epithelium
• lamellar granules
• tonofibrils

SS :

• cuboidal epithelium in 3 layers
• produces lamellar bodies
• first time golgi apparatus appear

SB :

• tall columnar epithelial cells
• constantly renew keratinocytes
• home to melanocytes

Question 8

What is psoriasis?

Answer 8

Statum corneum is produced in abundance every 2-3days instead of normal 28-40 days

Question 9

What is hyperkeratosis?

Answer 9

Too much keratin on surface of skin

Question 10

What are the other cells in the epidermis? State their functions

Answer 10

• Melanocytes : produce melanin
• Langerhans cell : present antigens to T lymphocytes
• Merkel cells : mechanoreceptors cells associated with sensory nerve endings

Question 11

What are the types of skin

Answer 11

• Non-hairy / thick skin
• Hairy / thin skin

Question 12

State the c and fs of non hairy skin

Answer 12

C :

• palmar surface of hands and foot
• thicker strana corneum
• thinner dermis
• higher mechanoreceptors

F :

• increase friction between skin surfaces
• increase sensation

Question 13

What are the differences between thick and thin skin

Answer 13

Question 14

What is skin appendages? Give examples

Answer 14

skin associated structures that serve a particular function

• Hairs
• arrector pili
• sebaceous and sweat glands
• nails

Question 15

How many types of hair are there? Describe them

Answer 15

• Lanugo : covers developing fetus
• Vellus : replaces lanugo

Short, thin, light coloured, soft

• Terminal : Head, axillae, external genital region

Long, wide, dark coloured, coarse

produced by testosterone

Question 16

What rae the functions of hair?

Answer 16

• Thermoregulation
• Sexual attraction
• sensation
• protection

Question 17

What are the C&Fs of Arrector pili muscle?

Answer 17

• smooth muscle fibres attached to papillary region of dermis (origin) and hair bulb (insertion)
• fight or flight resonse and cold - causes involuntary contraction
• may induce sebum release from sebaceous glands

Question 18

What are the types of mechanoreceptors in the skin?

Answer 18

• thermoreceptors
• nociceptor : pain
• meissner : touch (*Merkel in non hairy skin)
• meissner corpuscle : detect tapping and flicker movements
• pacinian corpuscle : vibration
• ruffini’s corpuscle : joint movement and tissue stretch
• root hair plexus : vibrations in hair shaft

Question 19

What are the C&Fs of nails

Answer 19

C :

• distal surface of phalanges
• a-keratin, nail plate, nail matrix and nail bed, grooves surround nail

F :

• protect distal phalanx and surrounding soft tissue from injury