Histology of the skin Flashcards
what is the integumentary system and what does it consist of
largest organ of the body, 16% body weight
forms a physical barrier between internal and external environment
skin, sweat glands, sebaceous glands, hair and nails
functions of the integumentary system
prevention of loss of water
protection from environmental insults and bacteria
immune function, sensory function
regulation of body temperature
synthesis of vitamin D under the effects of sunlight
histological image of the skin
epidermis with keratin
dermis
dermal ridges that are interrogating with epidermal ridges
several blood vessels also present
label the layers top to bottom
stratum corneum
stratum lucidum
stratum granulosum
stratum spinosum
stratum basale
dermis
label the histological layers
stratum corneum
stratum lucidum
stratum granulosum
stratum spinosum
stratum basale
dermis
stratum basale
mitotic activity
cells are cuboidal/columnar
basophilic
cells move upwards
stratum spinosum
thickest layers
cells are polyhedral shaped
centrally located nucleus
langerhans cells present
stratum granulosum
3-5 layers
shape of cells is flat
stain basophilic due to keratohyaline granules (have proteins material in them)these help with keratinisation
stratum lucidum
translucent
eosinophilic
ony present in thick skin
stratum corneum
horny layer
dead keratinocytes and anucleated (originated in the basale and migrated all the way up)
this Layer is replenished every few weeks
what do desmosomes do
bind the cells together
what are the different cells in the epidermis
keratinocytes
langerhans
melanocytes
merkel
label the cells in the epidermis
granules
keratinocytes
langerhans
melanocyte
merkel
tactile disc
sensory neutron
keratinocytes
originate in basale
move up spinosum
lose nucleus as they reach corneum
langerhans
in spinous
pale staining cells
melanocytes
pale staining
involved with formation of melanin/pigment in skin
provides protection against UV light/sun
come from neural crest cells
Merkel cells
mechanoreceptors
help with sensing light touch
from neural crest cells
vitiligo
autoimmune destruction of melanocytes
symmetrical depigmentation areas
albinism
no melanin
acanthosis
thickening of the stratum spinosum of the epidermis
typically seen in epidermal hyperplasia
hypergranulosis
thickening and prominence of the status granulosum of the epidermis
often in response to chronic mechanical irritation of the skin
hyperkeratosis
thickening of the stratum corneum of the epidermis
orthokeratotic hyperkeratosis refers to hyperkeratosis without the presence of nuclei
parakeratosis
a form of hyperkeratosis in which nuclei are retained in the stratum corneum
seen in many conditions such as psoriasis
ulceration
discontinuity of an epithelial surface including the epidermis or mucous membranes
describe the image
seborrhoeic (fungal) dermatitis
thickened epidermis
disrupted by infiltration of lymphocytes associated with an accumulation of fluid between the keratinocytes
surface keratin layers still contain remnants of keratinocyte nuclei- parakeratosis
blood vessels in upper dermis are dilated and surrounded by lymphocytes and macrophages
dermatitis
thickened epidermis
lymphocytic infiltrate
clear areas of fluid accumulation
parakeratosis
dilated blood vessels
what is in this picture
Bowen’s disease
slow extending, lightly pigmented, scaly plaques
when biopsy: full-thickness dysplasia with prominent nuclear pleomorphism
histological: full thickness dysplasia with abnormal mitoses, lack of cellular maturation from top to bottom and pleomorphic keratinocytes, no dermis invasion as basement membrane intact, carcinoma in situ
what is in the image
squamous cell carcinoma
identified by keratin pearls (concentric rings)
layers of the dermis
papillary
reticular
papillary
loose connective tissue
small blood vessels
nerves
lymphatics
sensory receptors
meissners corpuscles
reticular
dense irregular connective tissue
larger nerves and blood vessels
glands
hair follicles
sensory receptors
pacinian corpuscles
Ruffini end organs
contents of dermis
glands
capillaries
nerves
lymphatics
hair follicles
connective tissue layers
lots of collagen and elastic fibres
give strength and resilience to skin
elastic fibres give elastic recoil
fibroblasts help with healing and regeneration
three types of dermal gland
merocrine
apocrine
holocrine
meorcrine
sweat (eccrine) glands
predominant in most areas
thin secretion (exocytosis/secretory vesicle going out)
cell remains intact
apocrine
puberty
only in the axillary and pubic areas
thick secretion (part of cell leaves with the secretory vesicle, thicker secretions)
holocrine
sebaceous glands
the whole cell detached and goes out with the vesicle
sebum is thick
label A,B and C
merocrine
apocrine
holocrine
label from purple on left
Ruffini ending
merkels disc
meissners corpuscle
Krause end bulb
nerve
pacinian corpuscle
Ruffini
encapsulated
touch and pressure sneery receptor
sense twisting or stretch or distortion
located in the dermis
pacinian
encapsulated
respond to vibration and pressure
present in dermis and hypodermis
meissners
encapsulated
respond to light touch
located at the apex of dermal papilla
Krause end bulbs
encapsulated
respond to low frequency vibration
merkel
unencapsulated
light touch
mechanoreceptors
somatosensory
which skin is pacinian found in compared to messiners
pancinian mainly in reticular layer of dermis and in both thick and thin skin
meissners mainly in thin skin
what is in the image
meissners
what is in the image
pacinian corpuscle
what is in the image and describe
pilosebaceous unit
hair is a highly modified keratinised structure, grows in the hair follicle
rector pili muscle sits in the papillary layer of the dermis
sympathetic innervation can cause pilo-erection by cold or fear
each hair has 1+ holocrine gland to secrete sebum that acts as waterproofing and lubricating agent for hair and skin
arector pili muscle
type of smooth muscle
involuntary
contraction makes the hair stand up
what is in the image
SG=sebaceous gland
AP=arector pili
N=nuclei
what does the image show
the build up of cutibacterium acnes
primary source of vitamin D in humans
photo activation in the skin
of 7-dehydrocholesterol to cholecalciferol
then converted first in the liver to 25-hydroxyvitamin D
and subsequently in the kidney to 1,25-dihydroxycholecalciferol
4 stages of wound healing, brief
- blood clots at the site by releasing platelet-derived growth factors
- macrophages and neutrophils enter the wound as the inflammation begins, epithelial cells from cut edges of stratum basale migrate beneath and through the blood clot
- under growth factors and hydrolytic enzyme release from macrophages the fibroblasts proliferate and produce new collagen to form granulation tissue, contains growing capillaries
- epidermis re-establishes over the wound site, excessive collagen remains in the dermis as scar tissue
