Anatomy of the skin - Part 1 Flashcards
How much does the skin make of the total human body weight?
16% with a 1.5-2mˆ2 SA
What makes our skin unique?
We lost our hair through evolution as our skin was open to the savannahs we became bare and as we began to run, it became sweaty to cool our skin down
How does sweating allow us to lose heat
Our muscles generate heat from movement and sweat evaporates the heat from our skin
Why is the skin our first line of barrier?
It protects our internal organs and underlying tissues from the environment
What does the keratin in our skin do?
Protects against abrasion and acts as a water repellent
What pigments our skin and protects it prom UV radiation?
Melanin
Where are lipids stored in the skin?
In the adipocytes in the dermis and adipose tissue in the subcutaneous layer
How does the skin help us make sense of the world around us?
Through touch, pressure, pain and relaying info to the brain
Why is skin a composite organ?
Made of all 4 tissue types
3 layers of the skin
-Epidermis
- Dermis
- Hypodermis
Epidermis features
- A stratified barrier
- Made of keratinocytes
- Avascular
Dermis features
- Provides strength to skin through collagen and elastin
- Vascular
- Split into papillary and reticular layer
Cutaneous layer
Epi + dermis
Hypodermis features
- Fat reserve
- Made of adipocytes that make fat
- Subcutaneous layer
What is epidermis predom made of?
Stratified Squamous Epithelial tissue
What is squamous meaning
Scaly and flattened
How many layers of epidermis?
4 - 5 layers
- Thin skin
- Thick skin
What is the epidermis of the thin skin made of?
4 layers from outer to inner
- Stratum corneum - spikey layer
- Stratum granulosum
- Stratum spinosum
- Stratum Basale
Stratum layer
- Exists purely to form a barrier
- Spiky layer
- Dead, dried out without a nucleus, flat
Granulosum
- Granules dehydrates the cells and push them up
- Crosslinked by the keratin fibres, cells are held together
- Gaps filled by a waxy substance to prevent any leakage
Spinosum
-Intracellular bridges i.e desmosomes, links cells within the dermis
- Where the flattening starts
Basale
- STEM cells, columnar regenerative cells
- Cells divide and daughter cells migrate upwards and dehydrate and flatten along the way
The only dead layer of the thin skin is…
The corneum
Hemidesmosome
Attaches the stratum Basale to the Dermis layer, prevents layers from sliding off
Thick skin
- Extra layer stratum lucidum so 5 layers
- No hair
-Below stratum corneum and above granulosum - Come Lets Get Some Burgers
Dermis features
- Does not shed
- Two layers: Papillary and reticular
Dermis features
- Does not shed
Papillary layer
Pokes the epidermal ridges, close to the dermal papilla
- Highly vascularised layer that nourishes pap layer and basale layer
Retucular
- Mesh like structure
-Collagen, elastin + blood vessels, lymphatic and nerves - Gives strength to the skin
Plexus
A network of nerves, bloodvessels or both
Cutaneous plexus
- Present at hypo/dermis (reticular layer) junction
- Bigger blood vessels that supply nutrients to hypo, deeper part of dermis, hair follicles and sweat glands
Subpap
- Above cutaneous, branches from it
- Below pap
- Provides nutrients to upper dermis and epidermal layers
Hypo
- Subcut layer
- Dominated by adipocytes aka subcut fat that is used in fasting and insulation
- Common site of injection i.e hypo/subcut injections
1º burns
- Outer layers of epidermis
- Redness aka erythema, dry and painful
- No blisters eg most sunburns
- Skin still has a barrier of repelling water
2º burns
1st type: both epi and some layers of dermis
- Blisters and moist
- Pusy and red
- Heals in 1-2 weeks
2nd type: Epi + deeper layers
- Whitish, waxy areas
- Hair follicles and sweat glands remain intact
- Heals in a month
- Some loss of sensation and scarring
3º burn
aka a full thickness burn
- extends into the subcutaneous and may affect bone and tissue
- Varied color from waxy white
through to deep red or black
* Hard, dry and leathery skin
* No pain in these areas as
sensory nerve endings
destroyed
* May require skin grafting
* Weeks to regenerate + scarring
Where are the desmosomes most prominent
Spinosum
Where are desmosomes found
All throughout the epidermis
Where do desmosomes lose there holding strength?
In the granulosum layer so the cross linking of keratin holds it together
