Integumentary System A&P Flashcards
What is the term for skin?
subcutaneous membrane
What are the appendages of the skin?
Sweat glands
Sebaceous/oil glands
Hairs and hair follicles
Nails
What is the largest organ?
skin
Skin forms how much of the total body mass?
8%
What skin covers most part of the body?
thin, hairy (hirsute) skin
What skin covers the palm, sole, flexor aspect of digits?
thick, hairless (glabrous) skin
What are the 3 major regions (layers) of the skin?
epidermis
dermis
hypodermis/subcutis/paniculus (superficial fascia)
What are the 2 main layers of the skin?
epidermis and dermis
What is the hypodermis mostly made up of?
adipose tissue
What layer of the skin is the subcutaneous layer part of?
hypodermis
Is the subcutaneous layer technically considered part of the skin?
no
Explain epidermis
continuously self-renewing, keratinized stratified squamous epithelium
What are the cells of the epidermis?
keratinocytes
melanocytes
epidermal dendritic (langerhans) cells
tactile (merkel) cells
Explain keratinocytes
make up majority of the cells (about 90%)
produce fibrous protein keratin
Explain Melanocytes
10-25% of cells in the basal layer
produce pigment melanin
what does pigment melanin do?
gives color to our skin
What cell is important to the basal layer?
melanocytes
Explain Epidermal dendritic (Langerhans) cells
macrophages that help activate immune system (prevents skin infection)
play a role in facilitating skin allergic reactions (contact dermatitis)
Who is most at risk for infection and cancer?
person with defective langerhans cells
Explain tactile (merkel) cells
touch receptors
mostly found in thick skin
How many layers does the epidermis contain?
5
What are the layers of the epidermis? from superficial to deep
stratum corneum
stratum lucidum
stratum granulosum
stratum spinosum
stratum basale
Stratum corneum
cornified layer
stratum lucidum
clear layer found in thick skin - palms and soles
stratum granulosum
granular layer
stratum spinosum
spinous or prickle layer
stratum basale
basal layer
What layer of the epidermis is the deepest and firmly attached to the dermis?
stratum basale
What is another name for stratum basale?
stratum germinativum
Define the stratum germinativum
source of epidermal stem cells that undergo rapid division
How long is the journey from basal layer to surface?
25-45 days
What is the arrangement of stratum basale?
single row of stem cells
Where do the cells within the layers of the epidermis derive from?
stratum basale
Does stratum granulosum have a nucleus?
no
What layer of the epidermis is thin and has 3-5 cell layers?
stratum granulosum
Explain what happens in the stratum granulosum
cells flatten, lose their nuclei and cytoplasmic organelles
What do the granules of stratum granulosum contain?
lipid rich secretion which acts as a water sealant and filaggrin
Define filaggrin
protein that retains water within keratinocytes
In what layer of the epidermis do cells keratohyaline and lamellated granules accumulate?
stratum granulosum
Which layer of the epidermis is found in thick skin (palms and soles)?
Stratum lucidum
Explain stratum lucidum
thin, transparent band superficial to the stratum granulosum
What is the arrangement of stratum lucidum?
a few flat rows of dead keratinocytes
What layer of the epidermis contains 20-30 rows of dead, flat, keratinized membranous sacs?
stratum corneum
What layer of the epidermis makes ip 3/4 of the epidermal thickness?
stratum corneum
Explain what happens in the stratum corneum
the squames on the surface flakes off (makes the main content of household dust)
What are the functions of stratum corneum?
protects from abrasion and penetration
waterproofs
acts as a mechanical barrier against biological, chemical, and physical assaults
Are the cells of stratum corneum regenerative?
yes
What layer of the epidermis can be thought of as a wall of bricks and mortar?
stratum corneum
What are the bricks of stratum corneum?
flattened keratinocytes filled with keratin and filaggrin
what are the mortar of stratum corneum?
liquid mixture, which surrounds the keratinocytes and provides the water barrier
What diseases are related to the epidermis?
bullous pemphigoid
pemphigus vulgaris
psoriasis
atopic dermatitis
melanocytic nevi
melanoma
basal cell cancer
What is Bullous pemphigoid?
An autoimmune blistering disease, typically affects older pts
antibodies form to antigens directly beneath the basal layer of the epidermis at the dermoepidermal junction
How does bullous pemphigoid clinically present?
tense bullae on an erythemous base on the skin
What is Pemphigus Vulgaris?
autoimmune disease typically seen in young adults
autoantibodies are formed against antigens that lie in the intercellular spaces leading to decrease adhesions of the cells and thus skin breaks off
What is psoriasis?
the rate of epidermal turnover is increased
the accelerated rate doesn’t allow adequate time for differentiation which is recognized as a scale
What is atopic dermatitis?
caused by mutations in filaggrin
may be associated with other atopic diseases (asthma)
What is Melanocytic Nevi?
aka moles
benign collections of melanocytes
effects epidermis
What is melanoma?
malignancy of melanocytes
What is basal cell cancer?
composed of cells that resemble basal layer keratinocytes
effects stratum basale
How does basal cell cancer present?
pearly, erythematous papules or plaques with rolled borders and telangectatisias in sun exposed areas
What is the dermis composed of?
strong, flexible connective tissue
contains blood and lymphatic vessels and nerves which supply the skin, sweat glands, and hair follicles
What are the 2 layers of the dermis?
papillary and reticular
What does the papillary layer of the dermis do?
provides mechanical anchorage and metabolic support
What does the papillary layer of the dermis consist of?
areolar connective tissue with collagen and elastic fibers and blood vessels
What does the papillary layer of the dermis form?
numerous papillae which bulge into the epidermis
these are what form your fingerprints
What do the dermal papillae of the papillary layer of the dermis contain?
capillary loops
pacinian corpuscle
Meissner’s corpuscles
Free nerve endings
What parts of the dermal papillae are receptors?
Pacinian corpuscles
Meissner’s corpuscles
Free nerve endings
What are the pacinian corpuscles responsible for?
pressure and vibration
What are the Meissener’s corpuscles responsible for?
light touch receptors
What are the free nerve endings responsible for?
pain and heat receptors
How much of the dermis is made up of the reticular layer?
80% of the thickness
What is the reticular layer of the dermis?
thick collagen fibers provide strength and resiliency (granular tissues)
elastic fibers provide stretch-recoil properties
Which layer of the dermis is more superficial?
papillary
Which layer of the dermis is more deep?
reticular
What are the cells of the dermis?
Fibroblasts
macrophages
occasionally mast cells and WBC
What do fibroblasts look like?
flat and irregular in outline, with extended processes appearing to be fusiform or spindle shaped
What do fibroblasts do?
synthesize most of the extracellular matrix of connective tissue
usually adherent to the fibers of the matrix they lay down
When are fibroblasts active and for what reason?
active during wound repair and activity is influenced by various factors such as steroids, dietary content, and mechanical stress
What happened to fibroblasts with those with vitamin C deficiency?
there is an impairment of collagen formation, it is slowed down
What are keloids?
abnormal scars
How do keloids occur?
uncontrolled synthesis and excessive deposition of collagen at sites of prior dermal injury and wound repair - fibroblasts play a role!
What is the result of a keloid?
prominent scar that extends beyond the wound
Explain the clinical correlation of fibroblasts and keloids
fibroblasts are hyperactive, the overactivity of them results in the scar to keep growing
Are keloids hereditary?
you are genetically predisposed to keloids
What is a hypertrophied scar?
prominent raised scar that is localized to the wound
Explain the correlation of fibroblasts and hypertrophied scars
hyperactivity of fibroblasts results in a raised scar
What dermatologic conditions have a correlation to fibroblasts?
keloid and hypertophied scars
What is the difference between a keloid and a hypertrophied scar?
hypertrophied scars are localized to the wound (could turn into a keloid) keloids are continuously growing and spreading, not localized to the wound
What are mast cells?
defensive cells
Where are mast cells most numerous?
around blood vessels
What do mast cells look like?
round or oval, with many filopodia extending from the cell surfaces
In mast cells, what is the nucleus surrounded by?
vesicles containing granule (such as proteoglycan heparin, HISTAMINE, tryptase) responsible for inflammation