ic 8 : skin

Question 1

3 layers of the skin

Answer 1

epidermis : outer layer

dermis : middle layer

hypodermis –> subcutaneous layer : bottom layer

Question 2

5 diff layers in the epidermis

Answer 2

stratum basale : deepest layer

stratum spinosum : spiny layer

stratum granulosum : granular layer

stratum lucidum : clear layer ( ONLY IN THICK SKIN )

stratum corneum : outer layer

Question 3

histology of the epidermis

Question 4

features of thick skin ( 4 )

Answer 4

found on parts with very high contact –> palms , sole , fingers & toes

has stratum lucidum –> translucent layer of flattened keratinocytes

has sweat glands

but no hair & sebaceous glands

Question 5

features of thin skin ( 2 )

Answer 5

covers the rest of the body

has fair follicles , sebaceous glands & sweat glands

Question 6

functions of the stratum basale / basale layer ( 3 )

Answer 6

• deepest layer
• has basal cells that generate new skin cells thru cell division
• new cells gradually move up the layer

Question 7

functions of the stratum spinosum ( 2 )

Answer 7

• provides strength & flexibility to the skin
• has keratinocytes –> spiny appearance under microscope

Question 8

functions of the stratum granulosum ( 4 )

Answer 8

• keratinocytes cells that contain keratohydlin granules & keratin filaments start to flatten
• the granules contains proteins that binds to the filaments
• the keratinocytes filaments get aggregated to form dense bundles
• helps with structural integrity of the keratinocyte cells

Question 9

functions of the stratum lucidum 2 )

Answer 9

• only in thick skin

thin transparent layer of dead keratinocytes that provide extra protection

Question 10

functions of the stratum corneum (5)

Answer 10

keratinocytes loses their nucleus & organelles

become cornocytes filled with tightly packed keratin filaments

form the outer layer of the skin

acts as a barrier protecting against mechanical damage , pathogens & water loss

Question 11

process of how keratinocytes become skin (6)

Answer 11

kerationcytes in the stratum granulosum produces keratin & keratohyalin granules

keratinocytes move towards the surface & unergoes keratinization where they lose organelles & become flattened

keratohyalin granules & keratin crystallise to form granules & filaments

the keratohyalin granules has proteins that bind to the filaments

the filaments get aggregated into dense bundles

keratinocytes flatten & lose moisture –> forming a protective barrier against environmental damage , pathogens & water loss

Question 12

layers of the dermis ( 2 )

Answer 12

papillary layer : top 1/5 of the dermis layer –> has dermal papillae

reticular layer : rest of the dermis

Question 13

how are the epidermis & dermis layer held together 5

Answer 13

the dermis layer has dermal papillae

the epidermis layer has epidermal ridges

those 2 would interdigitate –> forming an interlocking structure

increases SA between the 2 layers & strength their connection , preventing them from splitting under pressure

shapes of the epidermal ridges determine our fingerprints

Question 14

special structures & its function in the dermis layer 4

Answer 14

hair follicles ( only in thick skin ) –> produces hair

arrector pili smooth muscle ( only in the thin skin ) –> small smooth muscle that attaches to hair follicies , making the hair stand

sebaceous glands ( only in thin skin ) –> secretes oil

sweat glands ( both !!! ) –> secretes sweat

Question 15

functions of the subsutaneous tissue 2

Answer 15

• anchors the dermis to deeper structures

contains adipose tissue for protection & cushion

Question 16

2 diff types & functions of sweat glands 10

Answer 16

eccrine sweat glands :
- majority of the sweat glands in the body
- sweat to skin surface
- helps to cool the body

apocrine sweat glands :
- only in certain locations –> like axilla ( armpits ) , areola & nipples
- larger than eccrine sweat glands
- usually connected with hair follicles
- secretion more viscous as it has more fatty acids & proteins
- odorous when broken down

Question 17

sebaceous glands ( location + functions ) 5

Answer 17

mostly connected to hair follicles

produces sebum –> oily substance containing fat , salt , cholesterol & proteins

functions :
- keeps hair from drying
- forms a protective film to prevent excessive water evaporation from skin
- inhibits bacteria

Question 18

acne

Answer 18

clogged or infected sebaceous glands & hair follicles

blackheads : dried sebum & keratin

pimples : infected black