L18 - the skin Flashcards
functions of the skin
protection metabolic function thermoregulation sensory organ rapid repair of injuries
metabolic function of the skin
vitamin D
protection function of the skin
moisture control
barrier to pathogens
barrier to UV
3 main layers of the skin
epidermis
dermis
subcutis
epidermis cell type
keratinised stratified squamous epithelial
epidermis
- produces keratin
- no blood vessels
- constantly being shed
- direct contact with the outside
layers of the dermis
papillary dermis
reticular dermis
dermis cell type
fibrous and fibroadipose tissue which supports the epidermis physically and metaboilcally
dermis
- contains blood vessels
- contains nerves and sensory organs
- contains some muscles
subcutis cells
adipose tissue with supporting fibrous bands
subcutis
- large blood vessels
which layer of the skin has no blood vessels
epidermis
what type of epithelium is epidermis
continually proliferating
thick skin
- no hair follicles
5 layers of the epidermis (in thick skin)
- basal layer (stratum basale)
- prickle cell layer (startup spinosum)
- granular layer (stratum granulosum)
- stratum lucidum (skin of sole)
- keratin layer (stratum corneum)
layers of the epidermis in thin skin - only 4
- basal layer (stratum basale)
- prickle cell layer (stratum spinosum)
- granular layer (stratum granulosum)
- keratin layer (stratum corner)
stratum lucidum
- Nuclei already begin to degenerate in the outer part of the stratum granulosum
- faint nuclear outlines are visible in only a few of the cells
- ONLY IN THICK SKIN
what type of cells are found in the stratum lucidum
Several layers of flattened dead cells
cells found in the epidermis
keratinocytes
melanocytes
langerhan cells
melanocytes location
stratum basale
function of melanocytes
synthesise melanin (pigment in skin) which is transferred to adjacent keratinocytes.
melanocytes under microscrope
have a halo surrounding the nucleus (white clearing around the nucleus)
what type of cells are langerhan cells
intra-epidermal antigen presenting cells
historically referred to as histiocytes
which layer of the epidermis are langerhan cells most easily recognised
prickle cell layer
stratum spinosum
sebaceous glands
secrete sebum
types of sebaceous gland
- associated with hair follicles and secrete sebum into hair follicle
- secrete sebum directly onto the surface of the skin
location of hair follicle
- Start quite deep down in sub cut tissue
- Extend through dermis and up though epidermis
eccrine glands
produce sweat (thermoregulation function)
apocrine glands
produce odour
which glands screen sweat
eccrine
arrector pili muscle
- smooth muscle fibres
- Make the hair stand on end of lay down flat, depending on how warm somebody is
location of arrector pili muscle
Insert at one end into the follicle sheath just below sebaceous glands and the other in the superficial dermis
structure of hair follicle
hair bulb
hair shaft surrounding it
hair follicle surrounding it
cytoplasm of sebaceous gland under microscope
bubbly
due to sebum inside of it
epidermis in thick skin
thicker
skin receptors
- meissner corpuscles
- merkel cells
- pacinian corpuscles
- Ruffini endings
Meissner corpuscles
fast adapting
detect touch and vibration
location of meissner corpuscles
papillary dermis (in dermis)
merkel cells
slow adapting
touch and pressure receptors
pacinian corpuscles location
deep in skin
pacinian corpuscles
fast adapting
rapid touch, pressure and vibration
Ruffini endings
slow adapting
pressure and vibration
lamella of pacinian corpuscle
composed of flattened Schwann cells and endometrial fibroblasts
what is between the lamella of the pacinian corpuscle
- fluid
- collagen fibres
- capillaries
which stains should and should not be used to see Merkel cells
not H&E stain
should use CK20
location of Merkel cells
basal layer of epidermis
which layers of the skin does first degree burn penetrate?
epidermis
which layers of the skin does second degree burn penetrate?
epidermis and dermis
which layers of the skin does third degree burn penetrate?
epidermis, dermis and sub-cut
why may 3rd degree burn not be as painful
you may damage nerve fibres and pain receptors
nociceptors
pain receptors
where is thick skin located in humans
- palms of hands
- soles of feet
which layer of the skin does basal cell carcinoma originate
stratum basale
which layer of the skin does squamous cell carcinoma originate?
epidermis
which layer of the skin does malignant melanoma originate?
Deepest layer of the epidermis, located just above the dermis
what is a wart?
small lumps on the skin
- extra keratin produces a rough, hard texture of a wart
what is the dermis made up of
connective tissue containing irregular bundles of collagen fibres plus networks of elastic fibres
papillary dermis
superficial
loosely woven
reticular dermis
deeper
thicker
denser
rete ridges
epithelial down growths which result from epidermis and dermis interdigitating with one another
dermal papillae
upward projections which result from epidermis and dermis interdigitating with one another
what is a blister?
- Fluid collects between dermis and epidermis
- Cushioning the tissue underneath, protecting it from damage
dermatome
A specific region of skin of the body innervated by the sensory fibres of a single segmental spinal nerve (spinal cord segment)
two groups of cutaneous sensory receptors
- Free nerve endings/unencapsulated nerve endings/simple receptors
- Encapsulated nerve endings/compound receptors.
free nerve ending receptors
nociceptors
thermoreceptors
encapsulated nerve ending receptors
mechanoreceptors
fast adapting receptors
pacinian corpuscle
meissner’s corpuscle
slow adapting receptors
Ruffini endings
merkel cells
which receptors are involved in detecting light stroking
Merkel’s disks
- Respond to light touch / discriminative touch
which receptors are involved in reading braille
Meissner corpuscles
- Allows for discriminatory touch and grip control
