06a: Connective Tissue Flashcards
Extracellular material is composed of:
- Fibers
2. Ground substance
List the subtypes of embryonic connective tissue.
Just mesenchyme
Embryonic (X) gives rise to which adult CT?
X = mesenchyme
All!
Mesenchymal tissue is composed of (X) cells that are (not/intra/inter) connected and derived from (Y) embryonic layer.
X = multi potential
Interconnected;
Y = mesoderm
T/F: Undifferentiated mesenchymal SC are only found in developing embryo.
False - persist in adult (look like fibroblasts)
List the subtypes of adult connective tissue.
- Connective tissue proper
2. Specialized connective tissue
List the subtypes of adult connective tissue proper.
- Loose (areolar)
2. Dense, irregular
In loose, areolar CT, (X) dominate and there’s lower (Y) quantity.
X = cells Y = fiber
In dense, irregular CT, (X) dominate and there’s lower (Y) quantity.
X = fibers Y = cell
T/F: Thickness of fibers in loose CT and dense, irregular CT is the same.
False - thicker in dense, irregular CT
Speak to the amount of ground substance in loose CT versus dense, irregular CT.
More ground substance in loose CT
List the subtypes of adult specialized connective tissue.
- Adipose
- Bone
- Cartilage
- Blood
- Dense, regular
What characterizes dense, regular CT?
Tightly packed fibers that are organized in one direction
Give examples of dense, regular CT.
- Tendon (M to B)
- Ligament (B to B)
- Aponeuroses (M to M)
List the general structural functions of CT.
- Connect epithelium to underlying tissue
- Encapsulate organ
- Resist forces
Principal cell of CT is (X). What’s its function?
X = fibroblast
Synthesize, maintain, and degrade all extracellular material
T/F: Fibroblast is constrained by surrounding matrix.
True
What might a fibroblast look like in a LM slide?
Flat, fusiform nucleus with long cytoplasmic processes
Extracellular material contains which fiber type(s)?
Elastin, collagen, reticular fibers
Ground substance composed of which compound(s)?
- Glycosaminoglycans (GAGs)
- Proteoglycans
- Adhesive glycoproteins
Collagen is made inside (X) and secreted by (Y).
X = Y = fibroblast
Collagen constitutes (X)% of total protein mass in body.
X = 20-30
Basic unit of collagen is (X). These units are arranged in (Y) structure.
X = alpha chain Y = triple helix
T/F: Collagen construction involves transcription, translation, and post-translational modification of alpha chains.
True
What’s procollagen?
The triple helix that forms from combination of 3 alpha chains
What’s tropocollagen?
Modified procollagen; frayed ends have been cleaved off upon entering extracellular space
A collagen fibril is composed of:
Self-assembled tropocollagen
Type (X) collagen assembles into fibers with (Y) appearance.
X = 1 Y = banded
Type 1 Collagen (fibers/fibrils) are visible in LM.
Fibers
Type 1 Collagen (fibers/fibrils) are visible in EM.
Both
Type 1 collagen accounts for (X)% of all collagen.
X = 90
What are the key properties of type 1 collagen?
High tensile strength and stretch resistance
Cartilage extracellular material composition.
50% ground substance (proteoglycans) and 50% type 2 collagen
Type 2 collagen appearance in LM.
Not visible (due to size/orientation)
Type 2 collagen fibers appearance in EM.
Don’t assemble into fibers! Random fibrillar network
Main component of reticular fibers is:
Type 3 collagen
(X) collagen fibers have high number of glycosylated residues with adjacent (Y).
X = Type 3 Y = hydroxylated groups
Large changes in organ volume is possible due to (X) fibers forming a (Y).
X = anastomosing type 3 collagen Y = flexible scaffold
(X) are (Y), which means they stain black with silver salts.
X = reticular fibers (type 3 collagen) Y = argyophilic
External/basal lamina is formed by (X). Describe the arrangement/structure.
X = type 4 collagen
Meshwork of dimers
Which type of collagen fibers act as “anchoring” fibers?
Type 7 collagen
Elastic fibers are typically found in high concentrations in tissues with which property?
Tissues that undergo short-term changes in volume
Elastic fibers can be selectively stained with:
Verhoeff’s stain (or resourcin-fuschin)
Elastic fibers are primarily known for which property?
Distensibility (allow stretching of tissues to several times their length and then return to their original form)
Why might elastic fibers usually be found with (X)?
X = collagen
To prevent over stretching of the structure
Fibrillin is a (X) that’s found in (Y) fibers.
X = glycoprotein Y = elastic
Describe structure of elastic fiber.
Elastin core surrounded by microfibrils made mostly of Fibrillin
Describe the shape/form of elastin.
It’s amorphous (no clear shape/form)
(Hydrophilic/hydrophobic) (X) has a strong tendency to curl up.
Hydrophobic;
X = elastin
Cross-links, called (X), regulate elasticity and provide structure in (Y).
X = desmosines Y = elastin
Marfan syndrome is a result of:
Genetic defect in Fibrillin (FBN1) gene
Which fiber(s) present in ground substance?
None; it’s non-fibrillar
GAGs are composed of (short/long), (branched/unbranched) chains of (X) units.
Long, unbranched (linear)
X = (no more than) 300 repeating disaccharide
GAGs are electrically (positive/negative/neutral) due to which part(s) of the structure?
Very electronegative;
Carboxylated and sulfated sugars
T/F: Hyaluronic Acid is a type of GAG.
True
What makes Hyaluronic Acid unique?
Unlike other GAGs:
- Non-sulfated
- Can have up to 25,000 repeating units
- Spun from cell membrane (instead of being synthesized in cell)
Dermatan sulfate is a(n) (X).
X = GAG
What’s the function of the massive electro(positivity/negativity) in GAGs?
Electronegativity;
Attracts positive ion (Na) that pulls water along with it (thus, causing hydration)
Hydration is critical in ground substance because:
- Prevents charged GAGs from repelling each other
- Enables pliable medium to resist compressive forces
- Allows diffusion of nutrients and gases
Describe basic structure of proteoglycan.
A protein with one or more GAG chains.
T/F: The attachment of GAGs on proteoglycan involves hydrogen bonding.
False - covalently attached
Many different proteoglycans attach to:
Hyaluronic acid (the non-sulfated GAG)
Neutrophils pass through ground substance by secreting:
Cathepsins and gelatinases
Pathogenic bacteria pass through ground substance by secreting:
Hyaluronidase
Most critical function of GAGs and proteoglycans is:
Hydration of the matrix
(X) function to glue together fibers, cells, and ground material.
X = glycoproteins
(X), an adhesive glycoprotein, enables cells to travel through matrix. It does this by attaching (Y) to (Z).
X = fibronectin Y = integrins of cell membrane Z = matrix elements (fibers and GAGs)
(X) allow(s) waste to be conveyed from and nutrients to be conveyed to the epithelium.
X = GAGs
(X) adipocytes make up white adipose tissue.
X = unilocular
Speak to the vascularization of white adipose tissue.
Highly vascular
Functions of white adipose.
- Mechanical absorption
- Thermal insulation
- Energy storage
How many lipid droplets found in unilocular adipocyte?
One
(X) adipocytes make up brown adipose tissue.
X = multilocular
Speak to the vascularization of brown adipose tissue.
Highly vascular
Round nucleus typically found in (unilocular/multilocular) adipocyte.
Multilocular
Functions of brown adipose.
Thermogenesis
Location of brown adipose.
Limited to inter scapular and paravertebral areas
About (X)% of Americans overweight/obese. And (Y)% classified as obese.
X = 70 Y = 40
Rates of adolescent obesity have (increased/decreased) by which factor in past 20 years?
Increased; 3x
Levels of Leptin, a (X), (increase/decrease) with amount of stored fat.
X = circulating hormone (adipocytokine)
Increase
What are the first two barriers encountered by a pathogen that tries to enter connective tissue?
- Secreted substances on epithelial lining (inhospitable surface)
- Basal lamina (Connective tissue barrier)
A pathogen that breaches epithelial barrier will find itself in (X) tissue. And facing (Y) cell.
X = Loose, areolar CT Y = the macrophage
Macrophage binds/engulfs pathogen and then releases (X) which initiate (Y).
X = cytokines Y = inflammatory response (dilation and leakiness of blood vessels)
In response to (X), epithelial cells express (Y) that bind to (Z) on neutrophils.
X = cytokines Y = selectin receptors Z = selectin
T/F: Neutrophil slowing down and binding selection receptors on epithelial cells causes diapedesis.
False - initially binds selection receptors, then slows and firmly binds integrin receptors
What’s NETosis?
Neutrophil Extracellular Trap (neutrophil dies but lobed nucleus is degraded and leaves chromatin behind to unravel into trap)
The “second round” of defense involves (X), which allow a more lasting response.
X = monocytes (macrophages)
Describe the process of antigen presenting by (X).
X = monocyte
Attaches piece of digested antigen to MHC II receptor
What are plasma cells?
Activated, differentiated B-lymphocytes
Plasma cells are specialized for (X). What’s unique about their appearance?
X = making proteins
Crescent-shaped piece of cytoplasm (cytocentrum) is site of golgi
