integumentary system and somatosensation Flashcards
subcutaneous
this is fatty layer deep to the epidermis and dermis
-protects underlying structure, stores energy, and is insulation for the body
8 functions of the integument
- protection (physical, chemical, UV)
- water regulation
- temperature regulation
- vitamin d synthesis
- sensory perception
- excretion by sercretion
- storage of blood (5% of total)
- non-verbal communication (Janice, cyanosis, really pale, moist, flushed –> can give alot of info about what may be happening in the body)
epidermis
- this is the most superficial layer
- avascular
- made of stratified squamous epithelium
- has five layers (four at thin skin)
stratum basale
- deepest layer of the epidermis
- attachment to basal lamina
- stem cells, melanocytes, and merkel cells
- cell division occurs
- just a single layer of cells thick
stratum spinosum
superficial to just the basale layer and deep to every other layer
- cells at this layer are healthy and living because they have a nucleus
- some cell division occurs
- langerhans cells and melanocytes are present
stratum granulosum
- this is directly superficial to the spinosum
- some cells still living
- keritinocytes produce keratonyalin and keratin
- water proofing occurs at this layer when cells release a lipid rich substance that coats the cells
what is ironic about the lipid rich protective coat that is secreted
it blocks cells from getting nutrients and releasing waste so ultimately leads to cell death
stratum lucidum
- this is only present in thick skin
- appears glossy and is at the palms and soles of feet
stratum corneum
- most superficial layer
- contains multiple layers of flattened dead, interlocking keratinocytes
- typically relatively dry
- permits slow water loss by insensible perspiration
four cell types of the epidermis
- keratinocytes
- melanocytes
- tactile cells (merkel cells)
- dendritic cells (langerhans cells)
keratinocytes
- protection physical and mechanical
- waterproof the skin
- vitamin D synthesis
- production of antibiotics and enzymes to detoxify skin
- joined by desmosomes
melanocytes
- produce melanin
- absorption of UV light
- transfer melanin to keratinocytes via cell processes
what is skin color determined by
skin color is not determined by the number of melanocytes but the amount of melanin produced. most humans have the same amount of melanocytes
melanin
-helps to protect from the sun and absorbs UV
tactile epithelial cells
-these are receptors to touch
dendritic cells
- part of the immune system
- take up foreign proteins bia endocytosis and transports them to the lymph nodes to begin an immune response
what structures are derived from the epidermis
- nails
- sweat glands
- hair
sweat glands
- these can be apocrine or eccrine
- these are widely distributed throughout the skin
eccrine sweat glands
-they are important for thermoregulation and widely distributed throughout the skin
apocrine sweat glands
- these are in special places like the arm pit, groin, nipples
- ceruminous glands: these secrete ear wax
- mammary glands: these secrete milk
- others secrete smells and oils etc
dermis
-highly vascularized, neurological structures within, sweat glands, hair follicles, and hair glands within
arrestor pili muscles
these attach to hair roots and cause hairs to stand during certain situations
vascular functions of the dermis
- supplys dermis
- supplys nutrients to avascular epidermis
- important in controlling body temp
nerve fiber functions of the dermis
- tactile (touch) receptors
- control blood flow
- control glandular secretion
papillary layer
this layer has rolling ridges to increase the surface area that it has in contact with the epidermal region superficial to it
- made of loose connective tissue
dermal papillae:
- nipple like projections that give this layer its name
- they increase surface area and allow for gas exchange, waste etc.
why is it important to increase the surface area between the epidermis and the papillary layer
this is because the epidermis has not blood supply so it must rely on diffusion for nutrients and this kinda explains why the more superficial layers are dying/dead cells because the nutrients cannot make it to them
friction ridge
- folds of epidermis and dermis on fingers, palms, soles, and toes
- these increase friction to help with grasping things
reticular layer
- this makes up the majority of the dermis
- made of dense irregular connective tissue with bundles of collagen fibers
cleavage lines
these are the collagen and elastin fibers organized in thin parallel bundles to resist stresses
-when the skin is stretched too much the fibers tear and form striae (stretch marks)
why is it important to try to make incisions along/parallel to the cleavage lines
this allows for a better healing process and less of a scar
skin changes with aging
- thinner skin
- decreased dendritic cells
- decreased vit D3 production
- decreased melanocyte activity
- dryer skin
exteroceptors
- found in the skin or mucous membranes
- these are the sensory receptors in the skin
types of skin receptors
non encapsulated tactile receptors - free nerve endings -tactile (merkel) disc -root hair plexus encapsulated tactile receptors -tactile corpuscles -lamellated corpuscles -bulbous corpuscles
free nerve endings
- pain and temperature
- found in the papillary layer of the dermis and deep epidermis
tactile disc
associated with tactile cells in the stratum basale of epidermis
-light touch
root hair plexus
- movement of hairs- light touch
- surround hair follicles in dermis
tactile corpuscles
- in tips of some dermal papillae
- light touch
lamellated corpuscles
- in the dermis, subcutaneous tissue, and some vicera
- deep pressure sensation
bulbous corpuscles
- in the dermis and subcutaneous
- deep pressure
what receptors are in the dorsal column medial lemniscus pathway
- tactile (merkle) disc
- tactile corpuscles
- root hair plexuses
what receptors are used in the anterolateral pathway
- bulbous coupuscles
- free nerve endings
receptive fields
- the sensory receptors that feed into a sensory neuron
small receptive fields have what
- good discriminatory touch to determine where something is affecting you
- this is important in your fingers, eyes, etc
big receptive fields have what
they have bad discrimminatory touch
dermatomes
area of the skin innervated by a single spinal nerve
-circumferential in the trunk and distorted in the limbs
shingles
- this is the reactivation of the chicken pox
- the virus travels down the sensory axons to the dermatome
