Connective Tissue Flashcards
Type 2 Collagen
Small Banded Fiber
Distribution: Hyaline and Elastic Cartilage, Eye
Fxn: Resists Pressure
Collagen Type 1
Large Banded collagen fiber
In: General CT, Tendon, Bones, Ligaments, Organ (capsules)
Function:Resists Tension
Type 3 Collagen
Small Banded Reticular Collagen
In: Lymph, Spleen, Liver, lung, cardiovascular, skin, bone marrow
Structural Framework
Type 4 Collagen
Sheet Like Layers
- Basement membrane, Basal Lamina
- Support/Filtration
Type 5 Collagen
Thin Fibrils
- Dermis, Tenson, Bone ligaments, capsules of organs, placenta
- With type 1
- placental ground substance
Type 7 Collagen
Thin Fibrils
- junction of dermis and epidermis
- anchoring fibrils in basement membrane
What are the 5 kinds fo connective tissue proper?
Loose (areolar) Dense irregular Dense regular Reticular Adipose
Where is dense regular connective tissues
Tendons, ligaments
Where is dense irregular connective tissue
Dermis of skin, nerve sheaths, spleen capsules, kidney, lymph nodes, testes, ovaries
-glands, GI tract, blood vessels (filling spaces just deep to skin)
Glycosaminoglycans
GAGs
- polysaccharides of repeating dissacharides
- Sulfated-gives the name (ex. Chrondroitin)
- also gives it a negative charge which attracts Na+ and water to help resist compression
- The protein attaching them is Hyaluronic Acid
What is the protein in unsulfated GAGs
Hyaluronic Acid
What are proteoglycans?
Protein Core with covalently bound sulfated GAGs
-important for binding and activation of growth factors
Glycoproteins
Ex: Fibronetin, lamin, enactin
FHave domains that bind components of ECM and integrins (found in basement membrane)
What is the general structure of a collagen Fiber
Made of many collagen fibrils. Firbil made of tropocollagen triple helix of alpha chains.
-Have overlapping regions and gap regions so it looks like dark/light pattern
What are the common amino acids in collagen
Every 3r amino acid is glycine
Other common ones: proline, hydroxyproline, hydroxylysine
Where is collagen made? What are the three steps
- Translated to preprocollagen in RER
- Hydroxylated/Glycosylated in RER and procollagen made and secreted by Golgi
- Outside of the cell procollagen peptidase cleaves to tropocollagen and spontaneous self assembly to make fibril
Are reticular fibers thin or thick
thin 0.5-2micrometers
Where are reticular fibers
soft tissues in lymph, liver, bone marrow, spleen
-provide the “scaffold”
What do you use to stain reticular fibers
Dont stain well with H&E, but they are pretty glycosylated so stain well with silver and PAS
Are elastic fibers thin
yes, much thinner than surrounding collagen in slides
What are elastic fiber cells made of
Elastin Core and fibrillin microfibrils.
Where are elastic fibers found? are they in regular and irregular ct?
Larynx, Muscular Artery
yes
Scurvy
Vitamin C deficiency. Vitamin C is a ofactor for proline hydroxylase
Ehlers Danlos
Collagen or enzyme related to collagen mutation. super felxible joints, succeptible to GI tear
Marfan
defect in fibrillin gene
Is fibroblast a fixed or wandering cell
fixed
What is the principal cell of ct? Where are they derived from
Fibroblasts. Mesenchymal cells
What do synthetically active fibroblasts do
produce procollagen, and ECM components
-look spindle shaped, and contain well developed RER and Gogli (dormant ones look very different with mostly heterchromatin)
Myofibroblasts
Have more actin and look like smooth muscle–help in wound closure and healing
What are pericytes
Undifferentiated mesenchymal cells associated with capillaries and small veules
- smaller than fibroblasts
- have characteristics of smooth muscle and endothelial cells
What are the two type of adipocytes
Unilocular and Multilocular
What do unilocular cells look like
A single large lipid droplet. it gets washed out in H&e stain
What are the functions of unilocular adipocytes
White/yellow fat
- Stored lipid (triglycerides)-made in adipocytes or liver
- Mobilization of lipids (under hormonal control)
- Produce Leptin (decreases food intake, increases E consumption)
What kind of fat do you find multilocular adipocytes
- Brown fat. (it is brown because it has cytochromes in the mitochondria)
- 2-5% of newborn body weight.
What is the fxn of brown fat? What special protein does it contain in the mitochondria
Production of heat controlled by smpathetic innervation.
Mitochondria have thermogenin which allows back flow of H+ ions across inner membrane.
What is hypertrophic Obesity
Adult onset, increase in cell size
What is hypercellular obesity
Childhood onset, increase in cell number
What is the main phagocytic cell of the CT
histiocyte/macrophage
Where do histiocytes originate? as what?
Bone marrow as monocytes.
-part of mononuclear phagocye system
What happens when macrophages fuse
they form foreign body giant cels that surround an phagocytose large foreign bodies.
Where are the parts of the mononuclear phagocyte system made
monocytes
Are plasma cells transient or fixed
Transient
Where do plasma cells originiate
B lymphocytes.
What is the typical appearance of a plasma cell nucleus
Cartwheel nucleaus.
Where are plasma cells found? what is there fxn
abundant at sites of chronic inflammation
make/secrete immunoglobins
Where do mast cells originate
Bone marrow
How big are mast cells
very big 20-30 um
What is the function of mast cells
inflammatory reponse.
The basophilic granules have primary mediators (heparin, histamine, eosinophil, chemotatic factors..)
secondary mediators as well (leukotrienes, thromboxins, prostglandins)
-anaphylaxis
How are mast cells activated
Antigen binds to an IgE receptor and activates adenylyl cyclase. leads to Calcium release which releases the primary mediators
it also activates phopholipases- which converts arachidonic acid the membrane leading to the secretion of secondary mediators.
What are mast cell primary mediators? how are they released
Histamine, heparin, eosinophil,neutropihl
released due to the Ca2+ and granule fusion. due to adenylyl cyclase cascade
What are mast cell seconary mediators
Leukortienes, thromboxins, prostglandins
adenylyl cyclase activates phospholipases which converyt arachidonic acid in the membrane and these are secreted.
