Skin Flashcards
Functions of the skin (7)
Thermoregulation Sensory perception Protection Waste excretion Water balance Vitamin D production Immunity
3 layers of the skin (top to bottom)
Epidermis, dermis, hypodermis
5 layers of epidermis (bottom to top)
Stratum basal, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
Stratum basal (function)
Where other cells arise from
Constantly dividing
Bound to underlying CT (dermis)
Stratum spinosum (function)
“Prickle cells” (spiny projections from desmosomes)
Ensures basal layer is not damaged as it is responsible for new cells
Stratum granulosum (function)
Granular layer
Keratinocytes accumulate keratin as they migrate to surface
Stratum lucidum (function)
Only in thick skin (soles and palms)
Lucid meaning clear
Filled with form of keratin (eleidin)
No hair
Stratum cornuem (function)
Dead cells on surface full of keratin No nuclei Flat Waterproof barrier Desquamation (cells shed)
What is keratinisation?
Cells flatten
Nuclei disappear
Full of keratin
Stratum corneum
4 cells of epidermis
Keratinocytes
Langerhans cells
Melanocytes
Merkel cells
Keratinocytes (function)
Protection
Produce keratin
Langerhans cells (function, location and structure)
Antigen presenting cell
Dendritic cell
Reside in spinosum
What does an antigen presenting cell do?
Ingest invading organism Digest Present antigens on surface of cell membrane APC to lymph node Warns immune system
Melanocytes (function, location)
Produce melanin (protect nuclei from UV light) Located in basal
How does a melanocytes protect the nuclei from UV light? What is the process of tanning called?
Melanocytes ingested by keratinocytes (endocytosis) and moved to apex to protect nucleus
Sun exposure = melanogenesis (tan)
Merkel cell (function and location)
Mechanoreceptors
Present in highly sensitive skin
Interact with cells in different layers
Located in basal
What are the two layers of the dermis (top to bottom)?
Papillary dermis, reticular dermis
How are the dermis and epidermis connected?
Contact surface is corrugated with epidermal ridges and dermal papilla
Papillary dermis (type of CT, location)
Thin
Just below epidermis
Loose CT
Reticular dermis (type of CT)
Dense CT
Thick collagen fibres
Strength
Hypodermis (structure and function)
Layer of adipose tissue
Underlines skin
Insulation, storage, cushioning
3 skin appendages
Nerves, sweat glands, hair (and hair follicles)
Nerves (different ____ for each ____)
Different nerve fibre for each sense (temp., touch, pain, pressure)
Two types of sweat glands
Merocrine, apocrine
Merocrine sweat glands (location)
Widely distributed
Apocrine sweat glands (location)
Restricted, under arms
Connected to hair follicles
Function of sweat glands (2)
Thermoregulation
Waste removal
Hair and hair follicles (structure and function)
Touch sensation and thermoregulation
Associated with sebaceous gland (sebum) and arrector pili muscle
What happens during vasoconstriction?
Cold
Blood flow to deeper regions
Contraction of pili muscles (goosebumps)
What happens during vasodilation?
Hot
Blood flow toward surface
Sweat (evaporation)
Arrector pili muscles relax
