Lecture 2- Anatomy of the skin part 2 Flashcards
Where is hair located?
- On the skin all over the body, but not the palms +soles of feet (thick skin).
- Most prominent on head
What does hair consist of?
- Hair shaft
- Hair follicle
- Arrector pili muscle
- Sebaceous gland
What is the role of the arrector pili muscle associated with hair?
- Contracts to make hair stand on end
- This is useful for insulation and also in fight or flight
What does the sebaceous gland associated with hair do?
- Produces sebum which is a natural moisturizer/ water repellent
- Sebum travels from the gland up the hair shaft to the surface of the skin
What is lanolin?
Sheep sebum, is used in skin care products
How does acne occur? What areas have increased risk of acne due to this?
- Acne is when hair follicles are blocked and infection occurs
- An increase in sebum production increases the risk of acne
- There is the highest production of sebum on shoulders +face and so this why acne common in these places
What are the two types of sweat glands?
- Eccrine = found everywhere, used for thermoregulation
- Apocrine = specialized, situated deeper in the skin for release in the base of the hair follicle. Are ‘oily’
What are the three types of skin receptors?
- Tactile
- Lamellar
- Bulbous
What is the basic difference between tactile and lamellar skin receptors?
- Tactile are situated shallow on the skin (near surface) and detect finer details
- Lamellar are situated a lot deeper in the skin and detect intense stimuli
What is the function/s of nails?
- Protect fingertips
- Enhance sensation: sensory receptors require deformation and fingernails allow this and when force is applied receptors will push against hard surface and change shape (particularly important for tactile receptors)
What are some examples of accessory structures of the skin?
- Hair
- Sweat glands
- Receptors
- Nails
How does skin anatomy relate to its function?
- Aging
- Pigmentation
- Skin cancer/ Vitamin D insufficiency
- Tattoo
What does the melanin pigment do?
Absorbs UV light protecting cells from damage
Where is the pigment melanin produced in the skin?
Melanocytes (cells)
Where is the melanin in melanocytes taken and how?
- Dendrites from melanocyte reach up between cells and melanosomes containing melanin bud off
- These vesicles transfer melanin to epidermal cells (outer layer of skin)
What are melanosomes?
Vesicles containing melanin
What do moles and freckles have in common?
- Both areas of skin that have higher levels of pigmentation
- Triggered by higher levels of sun exposure
How are moles and freckles different?
- Moles are a cluster of melanocytes (more cells i.e over proliferation), they 3D
- Freckles are due to melanocytes over producing melanosomes (more vesicles i.e over production), they 2D
Where are melanocytes found?
- Only found in stratum basal (deep level of epidermis at the dermal/epidermal boundary)
- Means are not shed so don’t lose pigment
Where are melanosomes found?
-Found throughout the epidermis and are therefore shed with keratinocytes
How does the density of melanocytes vary?
-Varies throughout the body but not between races
Why does human skin pigmentation vary?
- Skin pigment matches UV exposure
- As humans migrated out of Africa we lost the pigment in our skin
- There is a greater incidence of lightly pigmented skin at higher altitudes due to less UV exposure
What is Vitamin D essential for?
Normal calcium metabolism and strong bones (also effects mood if don’t have enough)
What is the disease that may arise due to not enough UV light?
- UV light exposure is required for synthesis of vitamin D
- When not enough vitamin D is synthesized this is known as Rickets
