Anatomy of the skin - Part 2 Flashcards
Where is hair found?
All over the body except the palms, soles and lips
What is a hair shaft?
- Projects from a hair follicle
- Made of keratinized cells and is dead
What does the erector pilli muscles do?
They pull on the hair shaft causing it to stand upright, trapping a pocket of hair that aids in insulation –> goosebumps
Root hair plexus
Collection of sensory nerves at the base of each follicle and heightens sensation
What are sebaceous glands?
Epithelial tissue that secretes sebus
Sebum
An oily secretion that is H2O repellent, nourishes the hair shaft and mousturizes the skin
How is acne caused?
Too much sebum, blocks the shaft and if is infected with bacteria, leads to acne
Sheep sebum
Lanolin
Eccrine functions
- Found in most areas of the skin
- Pour watery secretions directly
onto the skin surface aka sweat - Important in thermoregulation
and excretion - Some antibacterial action
Apocrine function
- Found in specific areas eg: armpit,
groin and around the nipples - Secrete sticky/oily and at times,
potentially odorous secretions
into the base of the hair follicle i.e not directly at the skin surface - Influenced by hormones, eg.
lactation
3 Types of receptors
- Tactile (close to surface)
- Lamellar
- Bulbous
all are also called corpuscles
Nails functions
- Protect fingertips / toes
- Enhance sensation
- Sensory receptors require deformation due to pressure to activate it and nails protect from too much deformation
When do we see visible changes in the skin?
Around the 45 year mark
What does reduced blood flow from the subpap layer cause to the epi + dermis
- Affects cells in the stratum basale –> they divide less
- Affects sweat glands –> less cooling
- Affects the melanocytes so less melaning production –> paler
- Affects the sebaceous glands so drier skin
- Slower skin repair as less nutrients are transported to the skin
What causes saggy skin?
The collagen in the reticular layer is less produced
What does smoking do to skin?
-Contains agents that thins out epi + dermis and hence accelerates aging
- Affects blood flow and hence affects the collagen and elastin production in the dermis
- also leads to poor wound healing, acne, skin and oral cancers
What causes premature aging?
Tobacco
What does vaping do to skin?
- Nicotine reduces blood circulation
in the dermis - Contact dermatitis (skin
inflammation) due to metal coating
on e-cigarettes that flakes off, can cause other type of cancers if ingested
What is melanin?
A yellowish brown pigment
Where are melanocytes found?
Stratum basale and are not shed
What do melanosomes do?
They are vesicles that transport melanin to any layer of the epidermis and can be shed with keratinocytes
What is a mole?
A lot of melanocytes in the stratum basale clusters, overproliferation can be caused by sun exposure
Freckles
Melanocytes produce too many melanosomes due to sun exposure, can be shed
What does vit D deficiency cause?
No active form of vit D i.e calcitriol and hence this causes rickets
How is vit D synthesised?
Through UV exposure of the skin
Who is susceptible to vit D deficiency?
Highly pigmented people at higher latitudes especially during winter
Who is susceptible to vit D deficiency?
Highly pigmented people at higher latitudes
Why does NZ have one of the highest skin cancer rates?
Air is thinner, ozone hole so lightly pigemented ppl are more suscepible
Two types of cancers
Basal cell carcinoma
Malignant melanoma
Basal cell carcinoma
- common but Usually benign
- Originates in stratum basale
- metastasis is rare as the cells of the stratum basale move up from the blood circulation
Basal cell carcinoma
- common but Usually benign
- Originates in stratum basale
- metastasis is rare as the cells of the stratum basale move up from the blood circulation
Malignant melanoma
- Rare but deadly if not treated
- Originates in the melanocytes
- Highly metastatic, gets thicker and spreads into the dermis
- Mortality rate depends on tumor
Where is the tattoo ink deposited?
Artificial pigmentation (usually ink) deposited deep within the skin
– Dermal layer, ie. Not shed
– captured (but not broken down) inside immune cells/scar tissue
* ‘Lena” tattoo, pigmentation of lymph node
Why is there pain during a tattoo?
There is a lot of pain receptors and free nerve endings in the dermis layer
