Skin: Structure and Function Flashcards
Melanocyte cytoplasm contains organelles called… these contain …….
Melanosomes have ….. and are mostly …… & ………
Each melanocyte is associated with many ……, forming an epidermal …… unit
melanosomes, pigment melanin
dendrites, basal, suprabasal
keratinocytes, melanin
Melanin absorbs ……
Full …… are transferred from melanocytes to keratinocytes via ……
They then form a …….. over the nucleus of the keratinocyte
light
melanosomes
protective cap
Langerhans cells have ……. , they are found in the ……. ….. level of the epidermis
]the nucleus looks like a ……. ……..
dendrites, prickle cell
tennis racket
Langerhans cells are though of as highly specialized …….
their function includes:
macrophages
Take exogenous antigen and present to T lymphocytes in skin or local nodes
Antigen presenting cells posessing surface receptors for IgG, IgE and C3b
Merkel cells are found in the ….. layer
They do not have ….., they are …… and are transducers of ….. touch
Sparse ……. connect these cells to neighbouring keratinocytes
basal
dendrites, mechanoreceptors, fine
desmosomes
What are the phases of hair growth?
Anagen
Catagen
Telogen
Structure of hair?
(down to up)
papilla, matrix, medulla, cortex, internal and external root sheath
Structure of pilo-sebacous unit?
Hair, arrector pili, sebaceous gland, hair shaft
Components of nail?
Made of specialized keratins
epidermis folds over creatin gposterir nail fold and cuticle.
White curve is lunula
nailplate and nail bed
The dermo-epidermal membrane is a …… membrane that acts as a ….. and ……
it has a key role in ……… interactions such as
semi permeable
barrier, filter
epithelial mesenchymal, growth, differentiation of basal cells, support, anchorage
The EDJ is formed of a …….. ……… to which the basal layer is anchored to from above and the cells of papillary layer from below
They are anchored by …….. which hook and link layers together
basement membrane
proteins
Defects in the anchoring proteins in the EDJ can result in
Bullous pemphigoid, which is when
Epidermolysis bullosa which is
Antibodies attack the connecting proteins in the EDJ
conegnital defect anchoring between the epidermis and dermis
Components of dermis?
Ground substance (polysaccharide mix)
Fibroblasts to manufacture collagen and elastin
Abundant collagen, some elastin
Superficial aspect has blood supply to supply nutrients epidermis
Nerves
Lymphatics
Macrophages, mast cells, langerhands cells, lymphocytes
Blood vessels form vertical plexuses to surface of skin in dermis t/f
F
parallel to skin!
Smaller lymphatic vessels are …….., larger lymphatic trunks are ……
Functions?
non contractile, contractile
Continual draingale of excess interstitial fluid, unwanted cells, plasma proteins
Immune surveillance by circulating lymp cells and Langerhans
channel microorganisms and toxins
Meissners Corpuscles are?
Sense vibration
located in papillar dermis
Pacinian Corpuscles are?
sense pressure
1mm big and look like onions, frequently seen in fingers. Located deep beneath dermis
Free nerve endings are?
smll and not encapsulated, associated with gllands and piloS units.
Sensitive to pain
Both demris and epidermis
Both sensory and autonomic
sebaceous gland?
Commonly empty into upper region of hair follicles,
‘holocrine process’ releases cells as disintegrated matter - oily greasy product (sebum)
Mostly in UPPER THORAX AND FACE
activates at puberty
foamy looking cells
Sebaceous gland function?
Sebum
serves to soften and waterproof skin
controls moisture loss
protects from fungal infections
sebaceous glands, appocrine and endocrine glands all release sweat t/f
F ]APP and END only
Apocrine glands?
found in axillae and perineum
Produce milky odorless fluid that produces distinctive odor after bacterial decomposition
Eccrine glands?
Empty directly on skin surface
Whole skin surface but palms soles and axillae in particular
sympathetic and cholinergic nerve supply (mental thermal and gustatory stimulation)
Secretes water, sodium and potassium ions (sweat)
Function eccrine?
cool by evaporation
soles aid grip
moisturizes palms
Sweat secreted by eccrine glands is less tan 10L per day
F
>10L per day
Where does the epidermis come from?
Ectoderm cells form a single layer of periderm, these layers gradually increase and then the periderm cells are cast off ( Vernix caseosa, also known as vernix, is the waxy or cheese-like white substance found coating the skin of newborn human babies, protective function)
Where does the dermis come from?
Mesoderm (below ectoderm)
Where do mlanocytes come from?
Neural crest (derived from folding of the ectoderm into the mesoderm)
keratin layer, granular layer, prickle cell layer, basal layer, dermis are all developed by 16 weeks t/f
T
Blaschko’s lines is the developmental pattern of skin, it follows nerves t/f
Developmental path of skin, doesn’t follow vessels skin or lymph
F
B lines visible in disease
it takes 48hrs for keratinocytes to move from bottom to top of epidermis t/f
F!! 28 days
Differentiation occurs via?
Daughter cells from basement membrane migrating upwards
Basal layer is usually ….. cell thick, it is small ……, has lots of ……. and is …… metabolically active
one, cuboidal, keratin, highly
Prickle cell later has larger …… cells with lots of …… that connect to ……..
polyhedral, desmosomes, intermediate filaments (keratin)
Granular layer is made of …… layers of …… cells, the granules within them contains ……… , there is a high …… content and the nuclei is …….
2-3, flatter, proteins (structural filaggrin and incolucirin help water barrier), lipid, lost
The prickle cell layer is lost in eczema t/f?
F
granular lost
Keratin layer is made of ……. and functions as a ……
corneocytes (overlappin non nucleated cell remnants) tight water proof barrier
What is the function of skin?
Strong barrier to antigens and organisms
Thermoregulation-BV and sweat glands
Fluid and electrolyte balance-sweat glands
Endocrine function-UV stimulation of Vitamin D
Protection from UV rays-melanin pigment
Immune function-Langerhans cells
Sensory function-touch, temperature, pressure
How is the itch sensation transmitted?
Unmyelinated C fibres
What are the different causes of itch? (4)
Pruritoceptive: something (usually associated with inflammation or dryness) in skin that triggers itch
Neuropathic: damage of any sort to central or peripheral nerves causing itch
Neurogenic: no evident damage in CNS, but itch caused by, e.g., opiate effects on CNS receptors
Psychogenic: psychological causes with no (currently detectable) CNS damage, e.g. itch in delusions of infestation
What systemic diseases are associated with itch?
Haematological, Paraneoplastic, Liver and bile duct, Psychogenic, Kidney disease, Thyroid disease
