Lecture 19: Integument Flashcards
What classification of epithelial tissue is seen in the epidermis?
Keratinized stratified squamous
What embryological structure gives rise to melanocytes?
What is the clinical relevance of this geneology?
Neural Crest
When melanocytes become cancerous (melanoma), the neural crest’s desire to migrate gets turned on. Therefore melanomas are likely to metastasize.
Where are melanocytes found?
Stratum Basale
Why might superficial Stratum Corneum cells be less able to attach to one another than deeper cells of the epidermis?
Because the lowered pH is unfavorable to cell junctions
What nail cell divides to form the majority of the nail?
Nail Matrix stem cells
Where might the dermal epidermal junction be more “zippered?”
Areas of increased mechanical stress
Where do we find the erector pili muscles?
In the Hypodermis
In what layer of the dermis are you likely to find more vasculature and nerve endings?
The papillary layer
What would we find in the medulla of a hair follicle?
Large, loosely connected, keratinized cells
In what layer of the eipdermis would we find “squames?”
Stratum Corneum
(This is what some people refer to the flat corneal cells as)
Cells of the Stratum Corneum do not have nucleii or organelles, what other layer of cells in the epidermis shares this description?
Stratum Lucidium
How do keratinocytes uptake melanin?
What is the term for this action?
They phagocytose it
Pigment donation
What is the function of a Pacinian Corpuscle?
Detecting pressure and vibration
What layer of the skin can be described as containing “polyhedral keratinocytes?”
The Stratum Spinosum
What does “desquamation” mean?
Means that cells will be sloughed off of the surface due to contact with the outside world.
Where is the water barrier of the epidermis primarily found?
Between the cells of the Stratum Granulosum and the Stratum Corneum
(It also exists between the layers of the Stratum Corneum)
Why does the Stratum Granulosum appear so dark purple on a normal stain?
Because keratohyalin granules are basophillic
What would we find in the Cortex of a hair follicle?
Hard keratinized cells and intermediate filaments
What are Langerhans Cells?
Antigen presenting macrophages that provide defense from pathogens
What do sebaceous glands secrete?
Sebum
Where does the initial melalanin production occur within a melanocyte?
The Premelanosomes
What layer of skin can only be seen in thick skin?
Stratum Lucidium
What do Langerhans Cells develop from?
Monocyte precursor
Where in the dermis would you find thicker collagen fibers and course elastic fibers?
The Reticular layer
Where does melanin sit in the nucleus of a keratinocyte?
As a “dark umbrella” over the nucleus
(How is Dark Umbrella not the name of a goth rock band?)
What binds the most basal cells of the stratum basale to the dermis?
Hemidesmosomes
What is the thickest layer of the non-keratinized portion of the epidermis?
Stratum Granulosum
(These cells produce karatin precursors to the layers above them)
What is a “cornified” cell?
A cell that is full of keratin
What do you call the protrusions of epidermis into the dermis?
Epidermal Rete or Ridges
What is the Lunula?
The crescent shaped white part at the base of the nail, near the nail matrix
What causes fingerprints?
Dermal Ridges of thick skin
What induces an epidermal cell to loose its nucleii and organelles?
Lowered pH
Where might you find a Meissner’s Corpuscle?
In the dermis, close to the epidermis
What allows you to detect fine touch, heat, cold, and pain in the skin?
Free nerve endings
What sort of secretion do Apocrine Sweat Glands use?
Merocrine secretion
(despite the name)
Why is the Stratum Lucidium named as such?
Because it appears “clear” relative to other layers.
Which sweat glands are activated during puberty?
Apocrine sweat glands
What sort of regulation to Apocrine Sweat Glands respond to?
Adrenergic
(adrenaline)
Where would you find a Pacinian Corpuscle?
In the juction between the dermis and the hypodermis, sometimes as deep as the fat.
What are Langer’s Lines?
Where are they found?
Regular lines of bundled collagen fibers as a response to the direction of stress
Found in the reticular layer of the dermis
What part of the melanocyte extends into the cell processes?
The melanosome
Which layer of the dermis lies directly under the epidermis?
Papillary layer
Where can Merkel Cells be found?
Stratum Basale
What is the cuticle?
The extension of skin covering the nail root.
How is the melanin producing enzyme induced to produce more melanin?
It is UV sensitive
What about apocrine sweat glands makes them produce odor when mixed with bacteria?
The merocrine secretion they release is high in carbohydrates
What part of the hair follical is invaginated by the dermal papillae?
The bulb
What is another name for the hypodermis?
Subcutaneous fascia
What rapidly dividing cells accout for hair growth?
Matrix cells
What layer of the skin is constantly shed?
Stratum Corneum
What four main cell types are contained in the Stratum Basale?
Keratinocytes
Stem Cells
Melanocytes
Merkel Cells
What sort of epithelium do we see in the ducts of sweat glands?
Stratified cuboidal
Where in the layers of the epidermis might you find cuboidal cells?
The most basal layer of the Stratum Basale
Throughout in the ducts
What are the characteristics covered in lecture for Merkel Cell Carcinoma?
Very rare
Highly Aggressive
Where can one identify Langerhans Cells?
In the Stratum Spinosum
What is the name of the adipose tissue of the hypodermis?
Panniculus Adiposus
What are the 5 layers of the epidermis from top to bottom?
Stratum Corneum
Stratum Lucidum
Stratum Granulosum
Stratum Spinosum
Stratum Basale
_C_ome _L_ets _G_et _S_un _B_urnt
Jon is not allowed to use this mnemonic**!
What two important compounds are found in the granules of the Stratum Granulosum?
Keratohyaline Granules
Filaggrin to assemble the keratin into bundles
What is an epidermal-melanin unit?
A melanocyte and the ≈36 keritinocytes that it transfers melanin to.
What binds the apical sides of the keratinocytes of the Stratum Basale?
Desmosomes
What type of secretion do sebacious glands use?
Holocrine secretion
What do we call an extension of the dermis into the epidermis?
A Dermal Papilla
What are Meissner’s Corpuscles?
“Footprint” looking structure perpindicular to the skin’s surface that respond to low frequency stimuli - not vibrations
What sort of regulation do we see in Eccrine Sweat Glands?
Cholinergic regulation
What cells provide “acute sensory perception” for light touch?
Merkel Cells
What do myoepithelial cells do?
Squeeze sweat glands to release the sweat product
Where would the Stratum Lucidum be present?
Palms and Soles of the Feet
Where are Apocrine sweat glands found?
Axilla, areola, nipple, skin of the anus, external genitalia
Where are Eccrine sweat glands found?
All over the surface of the skin, except the lips and external genitalia
Which layer of the skin thickens with pressure to form corns and calluses?
The Stratum Spinosum
What changes define a cell of the Stratum Corneum as we travel up through the layers?
Loss of organelles
Becoming full of mature keratin
What would you find at the core of a pacinian corpuscle?
A Myelinated Neuron
What is different about the karatinocytes of the Stratum Granulosum, relative to the keratinocytes of the Strata Basale and Spinosum?
They start producting visable granules - the others produce precursors
What is it about the plasma membrane of Corneal Cells that makes them such a good water barrier?
Their plasma membrane is coated with a layer of lipids from the lamellar bodies of the Stratum Granulosum
What is vellus hair?
The thin white hairs that grow on the body before terminal “post-pubescent” hairs replace them.
(Eg, the hairs of the face that forced some people to shave -or just look kind of ratty - well before they could actually grow a beard)
Which of the layers of the dermis includes the dermal papilla?
Papillary layer
What do we call the bundles of keratin filaments in the basal layer?
Tonofibrils
Where in the dermis are you likely to find a layer of loose areolar connective tissue?
Between the papillary layer and the epidermis
Why do surgeons cut along Langer’s Lines?
It promotes wound healing
What are the two steps of the production of melanin listed in the lecture?
Tyrosine -> DOPA (tyrosinase)
DOPA -> Melanin (polymerization)
What detects movements of hair?
Free Nerve Endings
