that skin lecture Flashcards
4 functions of skin
protective - acting as a barrier against microbes and other things
biochemical synthesis function as it makes vit D with help of UV influence
homeostatic function of controlling body temp
sensory function
what are the non keratinocyte cells in the epidermis and whats their function
langerhans cells which provide immune function to the skin
merkel cells which are the sensory nerve endings of the epifermis - light touch
melanocytes which produce melanin which protects from UV
what are the dermal papillae
this is the part of the dermis which projects up between the epidermal peg. this is where we fidn the keratinocyte stem cells - the epidermal pegs
what are the two components of the basal lamina
the lamina lucida and the lamina densa
what part of the basal lamina are the hemidesmosomes connected to
the lamina lucida
stratum spinosum cells synthesise what
cytoplasmic intermediate filaments called cytokeratin
what does cytokeratin do
gets bundled up to make the tonofibrils, combining with the granules in keratinisation releasing keratin to the stratum corneum.
what are the granules of the granular layer called
keratohyalin granules
function of the granules
these granules synthesise hydrophobic glycophospholipids.
what do the hydrophobic glycophospholipids of the granules do
release into the space between stratum granulosa and the stratum corneum, forming a water barrier
what type of collagen are the two parts of the dermis made of
papillary layer is made of type 3 collagen. the reticular layer is made of type 2 collagen.
cells of the secretory part of a sweat gland are different pigment under microscope to the duct cells - whys that
because the duct cells have more mitochondria. this is because they need energy to change the composition of the sweat produced
on the outer part if the secretory component of the sweat galnds are myoepithelial cells, what do they do
these squeeze the secretory acini and direct the secretions towards the ducts of the sweat gland.
whats the more superficial part of the basal lamina
the lamina lucida - the part the hemidesmosome links to
name of the cells in the sebaceous glands
sebocytes
describe the free nerve endings
Free nerve endings: these are the most common receptor in skin.
These are unmyelinated small diameter fibres.
Usually small swellings at distal ends = sensory terminals. Sensory terminals have receptors that can respond to various painful, thermal and chemical stimuli. The free nerve endings mainly respond to temperature, pain some movement and pressure, some itch in response to histamine.
Some of these nerve endings wrap around hair follicles acting as touch receptors for hair displacement.
describe the merkel discs
Free nerve endings within the deepest layer of the epidermis. These are tactile discs as they are associated with large disc shaped (merkel) cells.
These have small receptive fields so are involved in fine two point touch discrimination.
They are sensitive to fine touch and light pressure, and can respond to texture shape and edges of objects.
describe meisseners corpuscles
Located in the dermal papillae. Are especially common in hairless skin.
Branch sensory termional which is associated with adapted schwan cells, which is then ensheathed in a capsule. Shwann cell doesn’t make myelin when wrapped around.
They are encapsulated by schwann cells and then a thin oval of fibrous connective tissue.
they are rapidly adapting mechanoreceptors which are sensitive to touch
describe the Pacinian corpuscles
These are deep in the dermis and hypodermis.
They are made by a single dendrite being surrounded by concentric layers of collagen. Between this collagen is gelatenous interstitial fluid. The collagen is made by fibroblasts.
These respond mainly to deep pressure, when defromed the opening of Na+ channels makes an AP.
Rapidly adapt, so they dectect deep pressure and vibration quickly and only for short time. Helpful for running fingers over things to feel surface material.
When outer layer is deformed pressure wave goes through the fluid and to the dendrite causing AP
responsive to pressure and vibration
describe the ruffinis ending
Located in the dermis and subcutaneous tissues. They are made by nerve endings which are intertwined with collagen of the dermis.
Capsule surrounds the structure.
As it continues with dermal collagen it is sensitive to deep pressure and stretching or distortion of the skin. These can be proprioceptors as the degree of signal from them dictates stretch of joint or skin.
