WEEK 11 INTEGUMENTARY Flashcards
What is integumentary?
Skin and derivatives;hiar nails sweat glands, oil glands, mammary glands(apocrine sweat glands)
What is the function of integument?
Resistance to trauma and infection barrier to UV light Thermoregulation Sensation Nutrition Immune defence
What are the 4 cell types of the epidermis?
Keratinocytes
Melanocytes
Merkel Cells
Langerhans cells
What are keratinocyte cells and which epidermal layer are they in?
Cells formed by keratin and work by insulation (the principle cells) -found in stratum corneum (most superficial layer)
What are melanocytes and which epidermal layer are they found in?
Specialised cells that produce melanin(gives skin colour)- found in stratum basale (most deep epidermal layer)
What are the merkel cells and which epidermal layer are they found in?
Important cells associated with nerve terminals and detecting sensation- found in the stratum basale (deepest epidermal layer)
What are langerhans cells and which epidermal layer are they found in?
Wondering phagocytic cells that are important in body’s immune response- found in stratum spinosum
What are the 4 layers of the epidermis? (from superficial to deep)
Stratum corneum–>Stratum granulosum–> stratum spinosum–> stratum basale
What are the two sub layers of the dermis?
Papillary layer and dense reticular layer
What does the papillary layer consist of?
In the dermis (20%) and is in a wave like strucutre-dermal papilla- increase surface for gas exchange
What does the dense reticular layer contain?
Glands and hair follicles
What do dermal papillae form?
epidermal ridges that extend into dermis
Where are the epidermal ridges found ?
On the palms of hands and soles to increase friciton and ensure proper grip
What are sebaceous glands?
Glands that secrete sebum -waxy secretion that coats the surface of hairs
What are sweat glands and where are they found?
glands that produce sweat and found in dermis
What are nails and what are they produced by?
Keratinous structure produced by epithelial cells of nail root
Which 3 zones is the hair follicle divided into?
Bulb- swelling that originates in dermis or hypodermis
Root- produces the shaft
Shaft- portion above the skin surface
What is the hair structure?(cross section)
Inner medulla- soft and flexible soft keratin and cavity
Outer cortex- hard keratin
Cuticle- outermost layer (resistant to chemical decomposition)
What do the hair layers work as?
Protective lamina on hair surface
What are the 4 different hair types?
Lanugo hairs (found in developing foetus), Vellus hairs (unpigmented and all over body), intermediate hairs (upper and lower limbs) , terminal hairs (eyebrows, pubic hair, scalp-deeply pigmented )
What are aprocrine glands and where are they found?
Very large, duct doesn’t go straight onto epidermis-reaches to a hair follicle, only found on axillary region and genital area, oily secretion , creates body odor-from the bacteria in aprocrine glands
What are merocrine glands?
Much smaller than apocrine glands, has duct that goes straight to epidermis via sweat pore, only water secretion ‘typical sweat’- water with minerals-like on palms of hands (all over body surface) -thermoregulaton
What is the lunula of the nail?
Not attached to capillaries and is where the cells grow
What can skin colour be influenced by?
Carotene- orange-yellow pigment (but not a lot of colour)-body synthesises to vit A
Hemoglobin- bright red colour when combined with oxygen
Melanin- dark pigment- produced by melanocytes- most important component of skin colour
Why do women have skin in general than men?
Because when pregnant,they need vitamin D to be synthesised
What is the folate hypothesis?
That dark skin was not evolved to protect from UV and skin cancer but to protect folate- folate undergoes photolysis under UV and is critical for development- without it spina bifida (opening of vertebral column) occurs and developmental disorders occur
Why are the inuit people different from the norm?
Because they have dark skin colour in a northern environment- can’t get enough vitamin D from UV BUT can get it from diet- blubber, seal livers and whale blubber (fat and organs) - dark skin could also protect from irradiation (white snow)
What are 4 reasons for different skin colour?
- Number of melanosomes and degree of dispersion (dark coloured people=less dispersed, light coloured people- aggregate more like in freckles)
- Rate of melanin production (melanogenesis)
- Rate of transportation of melanosome
- Persons age- older-lighter skin
Does the number of melanocytes contribute to differing skin colour?
NO! It is the number of melanosomes
What are the two types of melanin?
Eumelanin and Pheomelanin
Which people is eumelanin typically found in?
Dark skinned or dark haired people (brown-black)
Which people is pheomelanin found?
people that have red hair also tend to have yellow-red brown skin characterised by the pheomelanin
What term is tanning knoen as?
Facultative skin colour -short term response (acclimatisation)
What causes gray hair to be gray?
Melanin production ceases and causes air bubbles which lead to the gray/white colour
What is Gloger’s rule?
That in endoderms, the more heavily pigmented forms tend to be found in hot and humid environments near the equator
What is the thermoregulatory hypothesis?
Where the transition to bipedalism helped conserve energy and protected from overheating which is why we may have evolved a dark skin colour -but weakness is that skin cancer was generally occuring after the reproductive age so it may not have been to protcect against UV
What is the folate hypothesis?
Dark skin was to protect folate from undergoing degredation by UV (photolysis)- folate is necessary for development, spermogenesis, and DNA expression - without it spina bifida can occur (opening of vertebral column)
What are the effects of vitamin D defficiency?
Rickets; bending of legs, improper tooth development, narrowing of pelvic inlet, can’t mineralise cartilagenous matrix in bones
