LC 2.3 Flashcards
does epidermis have blood vessels?
no nourished by the diffusion from blood capillaries extending to upper layers of the dermis
basement membrane
epidermis and dermis separated by a thin sheet of fibre called basement membrane. controls traffic of the cells and molecules between dermis and epidermis. reservoir for controlled release during physiological remodelling and repiar processes
dermis
- consist of connective tissue
- cushion body from stress and strain
- provides tensile strength and elasticity to the skin through extracellular matrix
- there are mechanoreceptors such as nociceptors and thermoreceptors
- there are papillary region (upper) and reticular region (deeper)
what is papillary region?
composed of loose areolar connective tissue which have fingerlike projections called papillae that extend towards the epidermis. this provide the dermis with bumpy surface and strengthen the connection between the two layers
what is the reticular region?
- dense irregular connective tissue
- there are collagenous, elastic and reticular fibers that weave throughout it
what are the layers of the epidermis?
- stratum corneum
- stratum lucidum
- stratum granulosum
- stratum spinosum
function of stratum corneum?
- form a barrier to protect from infection, dehydration, chemicals and mechanical stress
- dense netork of keratin help to prevent water loss
function of stratum lucidum?
- only present in palm and sole of feet
- filled with eleidin which is intermediate form of keratin
function of stratum granulosum?
- histidine and cysteine rich proteins which bind keratin filaments together
- build up within cells forming tonofibrils
- formation of hydrophobic lipid envelope responsible for skin barrier
function of stratum spinosum?
- synthesizing fibrillar proteins - cytokeratin
- build up within the cells forming tonofibrils
- tonofibrils form desmosomes which allow for strong connections
composition of sweat
- mostly water
- trace amounts of minerals, lactin acid and urea
- there are potassium, calcium and magnesium
- hypoosmotic relative to plasma
- moderately acidic to neutral levels
functions of sweat
- heat regulatory
what are the sweat glands?
- eccrine glands
- apocrine glands
what does eccrine gland do?
- found all over the body
- active in thermoregulation
- coiled deep in the dermis or hypodermis
- secrete all the time
what does apocrine gland do?
- coiled in the junction of the dermis and hypodermis
- secrete oily fluid with proteins, lipids and steroid
- secrete in periodic spurt
- there is odour after the bacterial microbial activity
regulation of sweating?
- controlled by the preoptic and anterior region of hypothalamus
- physical hear and emotional stress causes sweating
- physically heat induced sweating occurs throughout the body
- individual fitness level and weight affect the sweat rate
- high skin temperature reduces the hypothalamic set point for sweating
- high skin temperature has sweating response at higher temperature is much larger compared to at normal temperature
- physical and emotional stress causes sweating
function of melanocytes
- originate from neural crest
- excrete melanosomes into surrounding keratinocytes
- production of melanin
- protein responsible for the pigmentation of the skin, eyes and hair
- produced and stored in the melanosomes
- protection of the skin against UV
clinical significance of melanocytes
- vitiligo
- melanoma
- melanocytic naevus
