Connective tissue Flashcards
What are the two major elements of connective tissue?
Cells (Fixed and migratory)
ECM (fibers and ground substance)
What are the functional attributes of CT?
- Structure
- defense and protection
- nutrition
- fat deposition
All of the different types of connective tissue cellsare derived from what type of cells?
Mesenchymal cells which are derived from mesoderm
What are the different type of connective tissue cells?
Chondroblasts ADipocytes Fibroblasts Mesotheliacal cells Endothelial cells Osteoblasts
What are fibroblasts?
Cells that have the machinery for the synthesis and secretion of fibers and ground substance
What are fibrocytes
Inactive fibroblasts
How would one differentiate between active fibroblasts and inactive fibrocytes?
Look at euchromatin vs heterochromatin
Nucleus shape
Also, cellular organelles
What do fibrocytes typically stain?
eosin
When do fibroblasts divide?
may do so during wound healing. Otherwise nto often.
What is the effect of cortisol on fibroblasts?
Decreases activity
When can you appreciate nucleoli in fibroblasts/fibrocytes?
When they are active
Where does the triple helical structure of collagen form in the cell?
rER
What maintains the solubility of procollagen?
Propeptides at either end of the collagen molecule
What are the steps of collagen synthesis?
- mRNA produced and translated
- collagen helicies warp around each other in rER
- procollagen transported to Golgi, where they are further processed
- Released from Golgi/cell in secretory vesicles
What is the enzyme that removes the non-helical propeptides from the procollagen molecule? Where are they found?
Procollagen peptidases found in the Golgi
Why would you want to cleave the propeptide ends from the procollagen molecule?
To make the collagen insoluble
A lack of Vit C as in scurvy, affects what part of collagen synthesis?
hydroxylation of proline and lysine groups
What are myofibroblasts? Where do they become more numerous?
Cells that possess characteristics of fibroblasts and smooth muscle cells
More numerous in areas of wound healing
What proteins are present in myofibroblasts?
Actin and myosin
What is Dupuytren’s contracture?
microvascular ischemia leads in trauma to the palmar aponeurosis. Tissue repair ensues involving fibroblasts and myofibroblasts. Collagen type I replaced by type III. Contracture at the MP joints due to excess deposition of type III collagen and cross links with myofibroblasts. 4th and 5th digits most frequently involved
What are the two types of adiposites?
White and brown
What is the composition of adipocytes?
Large lipid droplet inside a cell–produces signet ring appearance
What is the intermediate filament that projects into the lipid space of adipocytes?
Vimentin
What hormone do adipocytes secrete?
Leptin
Mutations in leptin or receptor leads to what?
Obesity
What are lipodystrophies?
Abnormal distribution of fat on the body
Defects in Lamin A and lamin C lead to what type of lipodystrophies?
Accumulations in the head and neck.
What is the major difference between white and brown adipocytes?
White store single large droplet,
Brown stores many droplets
Why are brown adipocytes eosinophilic?
Have large amount of Mito
Why do brown adipocytes have a large amount of mitochondria?
To produce heat (newborns cannot shiver)
What is the characteristic feature of mast cells?
metachromasia with toludene blue
What do the secretory granules of mast cells contain?
Histamine
Heparin
Hemotoxic factors
What is the receptor on mast cells that trigger mass secretion of the granules?
FC
What are mast cells derived from?
Bone cells
Where are mast cells principally located? Where are they not found?
in CT proper adjacent to blood vessels and in the subepithelial layers of the respiratory and gastrointestinal tracts.
Not found in nervous tissue.
What do macrophages form from?
Stem cells to monoblasts, to monocytes
Where do monocytes migrate to, to develop into macrophages?
from CT to blood stream
What are the cytological attributes of macrophages?
- Oval nucleus with clumps of heterochromatin along the nuclear envelope; it is typically indented. It is eccentrically positioned in the cytoplasm.
- Well endowed with Golgi, rER, and lysosomes
What are giant cells?
Macrophages that have fused together
Langhans giant cells have what type of appearance?
Horseshoe nuclei at the periphery
Giant cells are characterisitic of what?
Chronic inflammation
What are the two types of migratory cells discussed in class?
Plasma cells
Leukocytes
What are plasma cells derived from?
B lymphocytes
What are the 3 signature features of a plasma cell?
Basophilia
Large negative Golgi
Clock face nucleus
Through which pathway are antibodies secreted in B cells (constitutive or regulated)?
Constitutive pathway
What do you not see in plasma cells?
Secratory vesicles
What is the first cell type to migrate into the sites of inflammation? Second?
- Neutrophils (day 1)
2. macrophages (day 2)
What is the role of neutrophils?
Remove damaged tissue
What are the two subclasses of embryonic tissue?
mesenchyme
Mucous
What are the two subclasses of CT proper tissue
Loose
Dense (irregular or regular)
What are the five subclasses of specialized CT?
- Adipose
- Reticular
- cartilage
- bone
- blood
What types of collagen are found in mucous tissue?
I and III
What type of fibers do you find in loose CT?
Elastic tissue
collagen
Reticular fibers
What type of cells do you find in loose CT?
Fibroblasts macrophages adipocytes mast cells undifferetiated cells
Where would you find loose connective tissue?
immediately deep to epithelium
surrounds blood vessels
What type of fibers would you see in dense, regular collagenous CT?
Densely packed, parallel array of type I collagen
Scattered elastic fibers
What type of cells would you see in dense, regular collagenous CT?
Scattered fibroblasts are flattened between the collagen bundles
Where would you find dense, regular connective tissue?
Tendons
Ligaments
Aponeuroses
If you have mucoid degeneration of the ACL, what will it look like?
A celery stalk
What type of fibers would you find in dense, regular, elastic fibers?
Elastin forms thin sheets of fenestrated membranes
Elastic fibers branch and run parallel to one another
Collagen fibers are few
What type of cells would you find in dense, regular, elastic fibers?
Scattered fibroblasts
Where would you find dense, regular, elastic tissue?
Ligamenta flava
Suspensory ligament of the penis
Vocal ligament
Arteries
What are the two structures made of elastin that are found within the walls of blood vessels?
Lamellae and laminae
Where is the internal elastic lamina found?
Internal membrane of an artery
Dense irregular CT has what type of fibers within it?
Tightly packed, type I collagen fibers oriented in many axes
Elastic fibers are interspersed
Dense irregular CT has what type of cells within it?
Scattered fibroblasts
Where would you find dense, irregular CT?
organ capsules
Dermis of the skin
Sleeve around nerves
What happens to elastic tissue as it is exposed to UV light over time?
Damaged
How much ground substance is in reticular tissue?
Little ground substance
What type of fibers are in reticular tissue?
Reticular fibers (type III collagen)
What type of cells are in reticular tissue?
Adipocytes
Where would you find reticular CT?
Red bone marrow
Liver
Lymphatic tissues
What are the:
- ground substance
- fibers
- cells
found in adipose tissue?
Sparse ground substance
Reticular fibers
Adipocytes
Where is adipose tissue found?
Subcuteneous areas, abdominal cavity
What is the:
- ground substance
- fibers
- cells
- Location
of mesenchymal CT?
- Ground substance = gel with GAGs, and glycoproteins
- Scattered reticular
- cells= fibroblasts
- Embryonic intremembranous formation
What is the:
- ground substance
- fibers
- cells
- Location
of mucous CT?
- Abundant, jelly with hyluronic acid and GAGs
- few collagen I and III
- Fibroblasts
- Umbilical cord as wharton’s jelly
What is the:
- ground substance
- fibers
- cells
- Location
of loose CT?
- abundant, with hyal acid and Glycoproteins
- loose collagen, reticular and elastic
- fibroblasts, macrophages, masts, undiff
- Lies deep to epithelum
What is the:
- ground substance
- fibers
- cells
- Location
of dense regular collagenous CT?
- Sparse with hyal, GAGs, proteoglycans, and glycoprotins
- Dense parallel arrary of Collagen I with scattered elastic fibers
- Scattered fibroblasts between collagen
- Tendons ligaments, aponeuroses
What is the:
- ground substance
- fibers
- cells
- Location
of Dense, regular ELASTIC connective tissue?
- Sparse with everything
- Elastin sheets, with few collagen
- Scatted fibroblasts
- ligamenta flava
What is the:
- ground substance
- fibers
- cells
- Location
of reticular CT?
- little ground subtanse
- Reticular
- reticuloycytes
- red bone marrow, liver, lymph
What is the:
- ground substance
- fibers
- cells
- Location
of adipose CT?
- sparse
- reticular fibers
- adipocytes
- subcutaneous areas
What are the two places that connetive tissue is derived from in development?
Mesoderm
Ectoderm (neural crest)
