Lecture #26: Integument System I Flashcards
True or False:
The dermis corresponds to lamina propria of a mucous membrane and is 0.5 to 3 mm thick.
TRUE
Where are primary dermal ridge not found in the body?
Not found:
- forehead - external ear - perineum - scrotum
During what months of fetal life are the primary dermal ridge formed?
Formed during 3rd to 4th months of fetal life.
True or False:
The primary dermal ridge is subdivided into two secondary dermal ridges by interpapillary peg.
TRUE
What is the interpapillary peg?
It is a downward growth of epidermis along crest.
What is the dermal papillae and what does it function to do?
Upward projections from each secondary dermal ridge.
The dermal papillae keep the epidermis from sliding off or your dermis. It locks the epidermis down.
What kind of fibers make up the secondary dermal ridges?
Thin collagenous, reticular, and elastic fibers.
What are the functions of the integumentary system?
> protection from mechanical injury > prevents dessication > protects against foreign substances and microorganisms > protects against UV radiation > thermoregulation > regulation of blood pressure (via dermal capillary network) > excretion of metabolic waste products synthesis of provitamin D
Does thick skin display all five epidermal layers?
YES
Where is the thickest thin skin and thinnest thin skin found in the body?
Thickest This Skin -> on the back
Thinnest Thin Skin -> is on eyelids
Where are the only places in the body that thick skin occurs?
Thick skin occurs only on palms and soles and is hairless.
Fill in the Blank:
_________ skin is thicker on extensor surfaces than flexor surfaces.
Thin Skin
What stratum layer does thin skin lack?
epidermal layers less distinct and lacking stratum lucidum.
What is stratified squamous epithelium derived from?
Embryonic Ectoderm
What is the layers of stratum in the thick skin, starting with the deepest stratum?
Stratum basale (germinativum)
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum
Which two stratum layers make up the stratum of Malpighi?
Stratum Basale and Stratum Spinosum
What is the deepest stratum layer of the epidermis?
Stratum Basale
What type of cells make up the stratum basale layer?
Columnar to high cuboidal keratinocytes
True or False:
The stratum basale layer is multiple cell layers thick.
False - single layer of cells that are held together by desmosomes and hemidesmosomes hold the layer to the basal lamina.
Are the keratinocytes of the stratum basale highly mitotic?
YES - mitotic activity produces stem cells differentiating keratinocytes.
Highly Mitotic
What are 3 synonyms of subcutaneous tissue?
1) SubQ
2) Superficial fascia
3) Hypodermis
True or False:
Secondary dermal ridges occur in double rows and are branched.
True
Which 2 low-molecular weight keratins are produced by keratinocytes in the stratum basale layer?
Keratins 5 and 14
What type of polyhedral-shaped cells make up the stratum spinosum?
prickle cells
Which 2 high molecular weight keratins are found in the stratum spinosum?
Keratins 1 and 10
What do the tonofibrils form in the stratum spinosum layer?
They form intercellular bridges.
**On slide 16 in the integument system 1 lecture there is a micrograph of tonofilaments in the stratum spinosum layer.
True or False:
Keratohyalin granules develop in the stratum spinosum layer.
TRUE
In the stratum spinosum layer of the epidermis membrane-coating granules first appear. What do these lamellar bodies contain?
Lipids
Carbohydrates
Hydrolytic Enzymes
Is the stratum granulosum layer mutilayered or single cell layered?
Multilayered
What type of keratins are produced in the stratum granulosum layer?
Keratins 2e and 9
True or False:
The stratum granulosum layer is made up of flattened non-nucleated keratinocytes.
False - the stratum granulosum layer is made up of flattened nucleated keratinocytes.
What protein induces the cross-linkage of keratin filaments by disulfide bonds in the stratum granulosum layer?
Fillagrin
**these are known as keratohyalin aggregates.
Refer to Figure 11-6 for keratinization process. You should study this thoroughly.
Need to know the keratinization process for exam 3.
True or False:
There are no tonofilaments found in the stratum granulosum layer.
False - there are tonofilaments
Is the stratum lucidum found in thick or thin skin?
Thick Skin
What is the difference between the stratum lucidum and stratum granulosum when comparing the layer of flat keratinocytes?
Stratum Lucidum -> flat keratinocytes laking nuclei and organelles.
Stratum Granulosum -> flattened nucleated keratinocytes
True or False:
The stratum lucidum layer contains eleiden.
True
What does the cytoplasm of dead, flattened, enucleated keratinocytes in the stratum corneum contain?
Keratin cross-linked with filaggrin -> cornified cell envelope.
The cytoplasm is replaced by keratin.
Describe the extracellular component of the cornified cell envelope that is constructed of keratin cross-linked with filaggrin?
It is a multi-lamellar lipid layer covalently linked to involucrine.
What is found in the intracellular portion of the cornified cell envelope of the stratum corneum layer?
> involucrine
small proline-rich proteins
loricrin
fillagrin and keratin complexes
What are the 2 major keratin products of stratum basale keratinocytes?
Keratins 5 and 14
Which 2 keratin types replace keratins 5 and 14 when basal keratinocytes migrate to the stratum spinosum layer?
Keratins 1 and 10
What 2 keratin types are found in the stratum granulosum layer of the epidermis?
Keratins 2e and 9
Which stratum layer has tight junctions?
Stratum granulosum
What is the major product of keratinocytes in the stratum granulosum layer? What function does this protein have?
non-intermediate filament protein, filaggrin.
Function: Filaggrin induces the aggregation of keratins.
What do hemidesmosomes hold together in the epidermis?
Found on the basal side of keratinocytes in the stratum basale and connect these cells to the basal lamina beneath.
True or False:
Keratin filaments, aggregated by filaggrin, interact with the inner side of the plasma membrane to form the cell envelope.
True
In which layer of the epidermis do you find tight junctions? Also, what are the 2 proteins that are contained in the tight junction that are components of the permeability barrier?
Stratum Granulosum
Contains claudin-1 and claudin-4, which are components of the permeability barrier.
True or False:
Both the epidermis and dermis are derived from embryonic ectoderm.
False:
epidermis -> derived from embryonic ectoderm
dermis -> derived from embryonic mesoderm
What are the characteristics of the dermis?
> dense fibrous irregular CT layer beneath epidermis
> derived from embryonic mesoderm
> induces development of epidermis and epidermal derivatives
> supports epidermis
List some characteristics of the hypodermis?
> loose CT that underlies dermis
> corresponds to superficial fascia of gross anatomy
> technically not part of skin
> may contain fat cells that can form a thick layer called the panniculus adposus.
What are the two layers of the dermis?
Papillary layer (closest to epidermis)
Reticular layer
Is loose CT found in the reticular layer or papillary layer of the dermis?
Papillary layer
What type of connective tissue is found in the reticular layer of the dermis?
dense irregular connective tissue
What structure separates the papillary layer of the dermis and the deep layer of the epidermis, the stratum basale?
basal lamina
Fill in the Blank:
Fibrocytes, macrophages, and adipocytes are found in the _________ layer of the dermis.
Reticular Layer
True or False:
In the papillary layer of the dermis there’s a network of fine elastic fibers and abundant capillaries.
True
What are Langerhans cells (dendritic cells) derived from?
monocytes
True or False:
Langerhans cells are not antigen-presenting cells.
False - they’re antigen-presenting cells.
In which layer of the epidermis are Langerhans cells primarily found?
Stratum Spinosum
Where do Langerhans cells of the epidermis typically migrate to?
lymph nodes
True or False:
Langerhans cells have Birbeck granules in their cytoplasm.
True
What do Birbeck granules contain?
Contain the proteins langerin and CD1a, which are involved in the uptake and delivery of antigens.
Langerhans cells leave the epidermis, enter the lymphatic system, and are transported to a regional lymph node. In the lymph node, what do Langerhans cells interact with and do?
Interact with T-cells in the deep cortex. The activated T-cell then re-enters the blood circulation, extravasate at the site where the epidermal antigen is present, and secrete proinflammatory cytokines.
In which layer of the epidermis are merkel cells typically found?
Stratum Germinativum
True or False:
Merkel cells may also act as diffuse neuroendocrine cells.
True
Do Merkel cells contain catecholamine-like granules?
Yes
What cell type act as mechanoreceptors in the epidermis?
Merkel cells.
What are Merkel cells derived from?
Neural Crest Cells
What type of cell are melanocytes derived from?
melanoblasts
What cell type do melanocytes inject melanin into?
Keratinocytes
True or False:
Melanocytes do not form desmosome attachments in epidermis.
True
What is the pathway for melanin formation?
Tyrosine -> 3,4-dihydroxyphenylalanine (DOPA) -> dopaquinone -> melanin
requires tyrosinase
True or False:
The epidermis starts as a single layer of ectodermal cells.
True
What does the single layer of ectodermal cells divide into during week six of development?
Periderm
Inner cuboidal germinal layer
What does the periderm slough off to form?
vernix caseosa
The inner cuboidal germinal layer continues to proliferate to form adult layers of the epidermis and derivatives. What derivative is developed at week 10 and 12?
10 weeks -> fingernails
12 weeks -> hair buds and toenails
What is the dermis derived from?
Embryonic Mesoderm
True or False:
The epidermis starts as a single layer of ectodermal cells.
True
What does the single layer of ectodermal cells divide into during week six of development?
Periderm
Inner cuboidal germinal layer
What does the periderm slough off to form?
vernix caseosa
The inner cuboidal germinal layer continues to proliferate to form adult layers of the epidermis and derivatives. What derivative is developed at week 10 and 12?
10 weeks -> fingernails
12 weeks -> hair buds and toenails
What is the dermis derived from?
Embryonic Mesoderm
