8 Skin Flashcards
*Q: Describe the basic structure of the skin. (5) Also includes? (2)
A: TOP: stratum corneum epidermis papillary dermis reticular dermis (hypodermis) subcutaneous /subcutis
pilo-sebaceous unit and sweat glands
*Q: What mainly forms the epidermis? variation? Growth?
A: keratinocytes (4 layers= keratinocytes differ in each: basal cell->prickle cell->granular cell-> corneocytes: lose nucleus)
layer names: stratum basale, spinosum, granulosum, corneum
-start at basement membrane and proliferate and move up skin -> differentiate -> whole purpose is to make keratin (protein)
*Q: What are langerhans cells in the epidermis? (2)
A: are dendritic cells (APC)
part of immune recognition
*Q: What are merkel cells in the epidermis to do with? What can happen to them?
A: sensation
can get MC carcinomas (can result in death)
*Q: What are melanocytes in the epidermis? (2)
A: mature melanin-forming cell
are dendritic and sit on basement membrane
*Q: What’s the function of the stratum corneum? Defects in it lead to?
A: barrier function of skin (stops irritants and allergies and prevents inflammation)
eczma (filagrin mutation is common for eczma patients)
*Q: What are corneocytes? where? make majority of?
A: differentiated, anucleated cells of keratinocyte lineage
constitute the majority of stratum corneum, the outermost layer of the epidermis
Q: Histology. How can you spot a melanocyte? Langerhans cell?
A: look like they’ve got a vacuole
wouldn’t be able to see
Q: Describe the stratum corneum structure. How can it be damaged?
A: between cells get a glue of sorts -> combo makes effective barrier
either the lipids or proteins are damaged -> lose function
*Q: What is the function of melanin? How is it produced? How is it transmitted to cells?
A: chemical that helps you block some UV damage to nuclei (surface is at risk as is exposed. damage to DNA can cause mutation -> if accumulates = cancer)
keratinocytes have messaging system that when exposed to UV -> produce melanocyte stimulating hormone -> melanocytes then produce lots of melanin -> hence get a tan)
packaged into melanosomes-> go down dendritic pathway -> interact with keratinocytes and transmit melanin to cells
*Q: What causes naturally darker skin?
A: don’t have more melanocytes but their baseline production of melanin is higher
by having more and larger melanosomes
Q: What happens if adults get vitamin D deficiency? (4)
A: have more chance of getting bone fractures
weaker immune system
lowered mood
less healthy hair growth
Q: What causes rickets? Important clinical features? (2)
A: vitamin D deficiency
- swelling in wrists and ankle joints
- bowling of legs
Q: What is a malignant melanoma?
A: cancer from melanocytes (uncontrolled growth)
*Q: Where is the epidermis derived from embryologically? Dermis? Result?
A: exoderm
mesoderm
- since they’re derived from different origins -> there’s a number of proteins involved in sticking them together
- proteins stick epidermis to basement membrane and proteins within BM stick it to itself and proteins stick BM to dermis
*Q: Lack of what component causes blisters? where? (2)
A: proteins (holds epidermis and dermis and BM together) in dermo-epidermal junction = basement membrane zone
Q: What is epidermolysis bullosa?
A: inherited skin disorders that cause the skin to become very fragile. Any trauma or friction to the skin can cause painful blisters
will heal with scarring but gets damaged constantly
*Q: What is the dermis? consists of? (3) 2 main cells? Thickness? (2)
A: supportive connective tissue matrix
70% collagen, elastin, glycosaminoglycan GAG
fibroblasts (make components above) and immune cells=dermal dendritic cells
varies in thickness (0.1mm eyelids and 3mm back)
Q: Histology. Describe collagen.
A: pink strings = collagen fibres
Q: Histology. Describe fibroblasts.
A: black nuclei
Q: How does the skin help regulate core body temperature? What should it be?
A: 36.8
-variations in skin blood flow (can restrict or dilate)
Q: What’s the structure of blood vessels to the skin? (3)
A: dermal papilla (right at surface)
superficial plexus (thicker than prev)
middle plexus
Q: How does sweating help regulate core body temperature? Production?
A: sweat (salty) cools the skin through evaporation
produced by eecrine (direct to skin surface) and apocrine (with hair shaft- more viscous sweat) sweat glands (coiled)
Q: Where are appocrine sweat glands mainly located? Subject to?
A: armpits and groin
subject to bacteria infection
Q: Where do melanocytes embryologically originate from?
A: neural crest
*Q: What are the functions of skin? (8)
A: -protect against injury
- protect against pathogenic organisms
- waterproofing and fluid conservation
- thermoregulation
- protection against radiation, absorption of UV and vitamin D production
- surface for grip
- sensory organ
- cosmetic
*Q: What makes the pilo-subaceous unit? (4)
A: follicle
hair shaft
sebaceous gland
pili erector muscle
*Q: Through which mechanisms does the skin have relationships with other organ systems? (4)
A: endocrine
immune
vascular
neural
*Q: Apart from keratinocytes, which cells are tin the epidermis? (3)
A: melanocytes (melanin production) langerhans cells (antigen presenting cell) merkel cell (involved in sensation)
*Q: What is the basement membrane zone? 3 key features. Why it is clinically important?
A: dermo-epidermal junction
-attached via hemi-desmosomes, anchoring plaques and proteins
genetic abnormalities in it can lead to abnormality of protein in this region and cause blistering eg epidermolysis bullosa
*Q: What does the subcutaneous layer consist of? (2)
A: connective tissue and fat
