Week 8 - Oral Mucous Membranes Flashcards
What are the main functions of mucous membranes?
- Absorption (saliva mixing with food allows for absorption through the membrane)
- Excretion (two way passage of materials)
- Protection
What kind of mucosa is masticatory?
keratinized (contains keratin, a protein that adds toughness)
Where is masticatory mucosa located?
- gingiva
- hard palate
What kind of mucosa is lining mucosa?
non-keratinized, thinner
Where is lining mucosa located?
o Alveolar mucosa
o Buccal mucosa
o Floor of the mouth
o Ventral surface of the tongue (underneath)
o Soft palate
What kind of mucosa is specialized mucosa?
Contains taste buds
Where is specialized mucosa found?
- Dorsal surface of the tongue (top)
- Little down the pharynx
Describe the lining mucosa when looking at a mouth
above MGJ, thinner and non-keratinized
Describe the mucogingival junction when looking at a mouth
separates attached and unattached gingiva
Describe the masticatory mucosa when looking at a mouth
below MGJ, tougher, denser, and keratinized
What is the microscopic organization of mucous membranes?
mucus membranes can have submucosa or no submucosa
Where is the submucosa found?
found in mucosa areas where you need salivary glands or fat layers
What is seen when there is no submucosa?
Mucoperiosteum instead
What is a mucoperiosteum?
A periosteum with a mucosal surface with the periosteum of bone to form an apparent single layer (very close/direct transition between bone and epithelium)
Describe the submucosa of the hard palate
What are the epithelial layers from superficial to deep?
- Stratum corneum/keratin layer
- Stratum granulosum/granular cell layer
- Stratum spinosum/spinous cell layer
- Stratum basale/stratum germinative/basal cell layer
Describe the stratum corneum
Cells are completely flat with no organelles. They are sacs of keratin proteinaceous mixture. High turnover rate, tend to exfoliate very easily
Describe the stratum granulosum
Flattened layer containing dense, dark granules. Reduced but present organelles
Where are keratohyalin granules found?
Stratum granulosom
What are keratohyalin granules?
Precursors to keratin
Describe the stratum spinosum
Characterized by round/ovoid cells
Point of which desmosomes (intercellular attachments) start to form
Describe the stratum basale
Single celled (cuboidal, progenitor cells) layer near the bottom
These cells replicate and make cells for all of the other cell layers
Describe the interconnection of epithelium
Where does epithelium rest on?
Basement membrane (separates epithelium from connective tissue)
What kind of intercellular attachments do epithelium exhibit?
One or more specialized intercellular attachments
i.e., desmosomes, tonofilaments
Is epithelium vascular or avascular?
Avascular
(receives all nutrients through diffusion from dermal connective tissue layer just below the skin)
How are cells arranged in epithelium?
Cells are packed together -> Exhibits a high degree of cellularity and relatively low volume of extracellular matrix
What does it mean that epithelium cells exhibit polarity?
- Cells exhibit apical, basal, and lateral borders
- Polarity is expressed in the distribution of cytoplasmic organelles
What are variations of stratum corneum determined by?
way the nuclei are organized or the way keratin is formed to determine the type of keratinization present
What is orthokeratosis?
Refers to normal keratin formation with clinically normal presentation
What is parakeratosis?
Presence/retention of pyknotic nuclei (nucelli with densely stained chromatin) in the stratum corneum
What is hyperkaratosis?
Abnormal thickening of the stratum corneum. May exhibit aberrant patterns of keratinization
What is dyskeratosis?
Abnormal keratinization below the level of stratum corneum (i.e. keratinization within the stratum granulosum and/or stratum spinosum)
What is gingival dyskeratosis characterized by?
by keratin pearls (areas of abnormal keratinization well below stratum corneum)
What are keratin pearls?
These are pathognomonic (something seen histologically that can only lead to one condition) for squamous cell carcinoma
What is acanthosis?
hyperplasia of the epithelial layer (increase in the number of cells)
Where is acanthosis seen in?
Palms of hands and feet (normal)
What is this?
acanthosis and parakeratosis
What is acantholysis?
Loss of intercellular attachments (desmosomes) between epithelial cells (keratinocytes)
What is metaplasia?
A reversible change in which one adult cell type is replaced by another (i.e. transition of columnar to squamous epithelium in the respiratory tract as a response to smoking)
What is dysplasia?
Refers to a disorderly but non-neoplastic growth of tissue including the epithelial layer
What is dysplasia characterized by?
pleomorphism, hyperchromatism, and loss of normal special orientation
What can dysplasia be a sign of?
Precancerous condition
- it itself is not cancer. It shows changes in density, darkness, so therefore something is wrong
What is this?
Hyperkeratosis and parakeratosis
White: intraorally when keratin gets wet it turn white
What is leukoplakia?
Thickened epithelial layer
What is inflammatory periodontal disease?
- Calculus and susceptibility of hosts causes attachment loss
- Results in apical migration of junctional epithelium
What is this?
Inflammatory periodontal disease
Where are melanocytes located?
In basal cell layer
Describe a melanocyte
Dendritic morphology (contains long processes)
What is the function of a melanocyte?
Synthesis of melanin pigment granules (melanosomes)
Where are langerhans cells located?
In stratum spinosum
Describe langerhans cells
Dendritic morphology
Characteristic Langerhans granules (looks like tennis racquet)
What are the function of langerhans cells?
antigen trap in epithelium and transfers antigen information to CD4 lymphocytes. “Sits there and waits for a foreign body to come along to calls CD4 cells to do their thing”
Where are merkel cells located?
In the basal cell layer
Describe a merkel cell
- Rounded morphology
- Contain characteristic “dense core” granules
What are the functions of merkel cells?
unknown, but something to do with tactile sensation of skin
Where are lymphocytes located?
basal and spinous cell layers
Describe a lymphocyte
Rounded morphology
What are the functions of lymphocytes?
associated with immune and inflammatory responses
- immune surveillance and antigen message processing
- inflammation: both humoral (antibody-antigen reaction) and cellular response (help clean things up)
What is the basement membrane?
what separates the epithelium from the underlying submucosa or connective tissue
What is the organization of the basement membrane?
consists of basal lamina (made up of lamina lucida and densa) and lamina reticularis (connective tissue)
What is the function of the basal lamina?
(has multiple layers of collagen that helps adhere connective tissue to epidermal layer
- Also has hemidesmosomes locking/connecting it to the basement membrane)
What are components of the lamina lucida?
- Contains bullous pemphigoid antigen (condition) and type VII collagen (anchoring fibrils)
- Also contains Kalinin, K-laminin, entactin, epiligrin, BMG-1 and classic laminin)
What are components of the lamina densa?
- Contains type IV collagen and type VII collagen
- Also contains fibronectin (helps with polarization and connecting and lining cells up), integrins (adhesion), BMG-1, and classic laminin
What are components of the lamina reticularis?
- Contains reticulin connective tissue
- Also contains type I and type II collagen and elastic (for strength)
What makes up the cytoplasm of the cel?
Intermediate filaments or tonofilaments (keratin 5 and 14)
Actin
Myosin
Talin
Vinculin
What are components of the hemidesmosome?
Bullous pemphigoid antigen 1 and 2 (BPAG1/BPAG2)
Cadherins
Syndecans
Integrin alpha6 and beta4
What are cellular attachments?
Desmosome
Hemidesmosome
Intermediate junction
Tight junction
gap junction
What do all 5 cellular attachments do together during trauma?
with trauma, all 5 work together to dissipate forces and help to absorb trauma and keep things from falling apart
What happens with loss of cellular attachments?
Common in response to inflammation
What is a desmosome?
circular areas of attachment between cells
What do desmosomes have that hook two cells together?
Tonofilaments
What are protein components that help with adhesion?
E-cadherin (desmoglein) and P-cadherin (desmocolin), plakoglobin, periplakin, evoplakin, desmoplakin I and II
Where are cadherins located? and what are their functions?
located in between. Is a sticky protein that functions in allowing for communication to occur between cells
What are the function of hemidesmosomes?
Semi-circular areas that contain tonofilaments that attach cell down to basement membrane
Where are hemidesmosomes found?
Along basement membrane
What are tight junctinos?
area of two cells pressed together so tightly that there is a seal
What are gap junctions?
small spaces in between the cells that allow for electrical communication
What is the function of fibroblasts?
Secrete collagen and elastin
What are the function of histiocytes?
Resident precursors of functional macrophages
What are the functions of monocytes?
Blood-borne precursor of functional macrophage
How are macrophages created?
Monocyte -> Histiocyte -> macrophage
What are the functions of macrophages?
Phagocytic cell capable of antigen processing
What are the functions of mast cells?
Secretes inflammatory mediators (i.e. histamine, heparin)
What are the functions of plasma cells?
Synthesis of immunoglobulins (antibodies)
What are the functions of endothelial cells?
Lining of blood and lymphatic vessels
What are transient cells within the lamina propria?
Neutrophills and lymphocytes
What are the functions of neutrophils?
Phagocytic cell capable of neutralizing antigens and killing bacteria
What are the functions of lymphocytes?
Humoral and cell-mediated immune response
