1 - structure & function of skin Flashcards
what are the layers of skin? (from superficial to deep)
- epidermis (stratified squamous epithelium)
- dermo-epidermal junction - dermis (connective tissue)
- appendages like nail, hair, glands - subcutis (fat layer)
what embryological origin does
a) epidermis
b) dermis
c) melanocytes
a) ectoderm
b) mesoderm
c) migrates from neural crest to epidermis
what are blaschko’s lines?
skin develops along these lines (won’t usually see on skin unless abnormality)
what are layers of epidermis? (superficial to deep)
- keratin (tough waterproof outer layer) - has corneocytes
- granular layer (2-3 flatter cells. large keratohyalin granules & odland/lamellar bodies)
- prickle cell layer (lots desmosomes)
- basal layer (1 cell thick, small cuboidal, lots keratin)
what are the 3 cell types that are also in epidermis? where are they found?
- melanocytes (pigment producing cells in basal layer of epidermis)
- langerhan cells (skin immune cells in prickle cell layer of epidermis, also in dermis & lymph nodes )
- merkel cells (mechanoreceptors between keratinocytes & nerve fibres)
what makes different pigment of skin?
darker skin & lighter skin have same number of melanocytes but darker skin has more larger melanosomes containing melanin
(more eumelanin & less phaeomelanin in dark skin)
*melanocytes contain melanosomes
what are 2 types of melanin?
- eumelanin (brown or black)
- phaeomelanin (red, yellow)
what is purpose of melanin?
to absorb light & protect basal layer from damage
what is epidermolysis bullosa?
genetic defect affecting molecules involved in skin adhesion
- skin doesn’t adhese well and blisters easily
what is dermis?
middle layer of skin = it’s the ground substance made of connective tissue and cells like fibroblasts, mast cells, lymphocytes, langerhans
what are
a) pacinian
b) meissner’s special receptors?
they are special nerve receptors that detect
a) pacinian = pressure
b) meissner’s = vibration
what are sebaceous glands?
- glands in whole body apart from soles of feet & palms of foot. lots in face & chest (think where acne).
- glands get activated in puberty - make sebum (oily stuff) that can make bad acne. but sebum good for lubricating skin and protecting against infection
what are apocrine glands?
- glands that inhabit underarm, groin, lower abdomen.
- unclear function
- release oily fluid into hair canal (like specialist sweat glands). more numerous in puberty = oily fluid (BO)
what are eccrine glands?
(glands that cool you down in gym)
- release sweat onto surface. millions across body. everywhere, especially palms of hands, soles of feet, forehead, underarms.
- sympathetic nerve supply (hot, stressed)
what do you get when each gland goes wrong?
a) sebaceous
b) apocrine
c) eccrine
a) bad acne
b) hidradenitis suppuritiva (like bad acne in horrible places, hard to treat)
c) miliaria = pustules in babies
what are 3 segments of hair follicle?
- infundibulum (hair shaft)
- isthmus
- hair bulb
what are different phases of hair growth?
- anogen = growing (have hair root on them)
- catagen = involuting
- telogen = resting (club hair - look like baseball bat)
- exogen = shredding
what is nail matrix, lunula and cuticle?
nail matrix = manufacturer
lunula = pale bit is end of nail matrix
cuticle = protects nail matrix (bit of skin)
what are areas of nail plate?
dorsal, intermediate, ventral (deepest)
what are functions of skin?
- barrier →physical, chemical & pathogen
- metabolism & detoxification →vit D metabolism, thyroid hormone metabolism
- thermoregulation
- immune defence
- communication
- sensory functions
