Connective tissue Flashcards
What are the 3 fiber types of the ECM? How do they stain?
Collagen
Reticular fibers
Elastic fibers
All stain eosinophilic
Bundles of collagen fibrils make up a single collagen _____.
Fiber
What cells produce the matrix of connective tissue?
Fibroblasts
What type of fiber can stain black (agyrophilic) with a special silver stain?
Reticular fibers because they have a special coat of glycoproteins and proteoglycans.
What type of collagen makes up reticular fibers?
Type III
What does the fine network of reticular fibers in the liver do?
Bind the connective tissue (stroma) to the parenchymal cells.
What type of fiber stains black with a Verhoeff’s stain?
Elastin fibers
Where do you find elastic fibers?
Surrounding blood vessels
Who are adipocyte organized?
Surrounded in clumps of septa - flat plates of dense connective tissue - that carry blood vessels.
What cell type is unilocular? Multilocular?
Unilocular = white cells Mulitlocular = brown
What is the function of brown cells?
Generate heat
What shape do fibroblasts have?
Fusiform
What are the type of general connective tissue?
Loose (areolar)
Dense irregular
What are the types of special connective tissues?
Dense regular Bone Cartilage Reticular Adipose Blood
Loose connective tissue has ____ fibers and _____ cells. Dense irregular connective tissue has _____ fibers and _____ cells.
Thin, many
Thick, few
What do mesenchymal stem cells give rise to.
Fibroblast Chondroblast Osteoblast Reticular cell Adipocyte
What are fibrocytes?
Fibroblasts residing in older established connective tissue that his much lower levels of activity.
What is the primary fiber type surrounding adipocytes?
Reticular fibers
What is in the interior of an adipocyte?
A single lipid droplet that can grow or shrink
How do brown fat cells generate heat?
Thermogenin (aka UCP1) a membrane protein in the inner mitochondrial membrane uncouples oxidation from phosphorylation, releasing energy as heat.
Phagocytic activity of macrophages is mediated by what?
Immunoglobulins and the serum complement system.
Macrophages have matured what what hematopoietic cell
Monocyte
What is the life cycle of a macrophage?
40 hours in circulation-> several months or more in the tissue and can still undergo mitosis
What are antigen-presenting cells?
A type of cell (e.g. macrophages) that ingest foreign material and then “present” it on their surface to encourage activation of lymphocytes in the immune response.
What are MALT cells?
The only type of lymphocyte present in high numbers in a normal (i.e. not pathological) state.
What does the plasma cell do?
When stimulated, it ramps up production of antibodies against the antigen that stimulated its proliferation.
Describe mast cells.
Mast cells are related to basophils and IgE. They reside in the peripheral blood compartment along the arterial side of blood vessels. When stimulated by an antigen, they release a vast number of inflammatory and chemotaxic agents.
What are 7 substances in granules secreted by mast cells?
Heparin Histamine Tryptase Superoxide dismutase Aryl sulfatase Leukotrienes
What is ground substance?
Interfibrilla soluble complexes of long carbohydrate polymers linked to proteins. They attract and bind water, connecting cells and fibers.
Do fibroblasts produce both connective tissue fibers and ground substance?
Yes
What is the basic structure of collagen?
Three polypeptide alpha chains (30 diff kinds) twisted around each other to form triple helices.
What type of collagen is type IV?
Non-fibrillar
What collagen types are fibrillar?
I, II, III, V, VII
What is the most common and abundant type of fiber in CT?
Type I collagen
What molecules make up collagen fibrils?
Tropocollagen molecules arranged in a staggered array (produces a banded appearance)
What is the major collagen type of the basal/external lamina?
Type IV
What collagen type makes up reticular fibers?
Type III
What collagen type binds Type III reticular fibers to the the Type IV basal lamina?
Type VII
What is the structure/formation of elastic fibers?
Elastic fibers are made of the glycoprotein, elastin. They are surrounded by a scaffold of very small fibrils containing fibrillin protein.
What are the 3 primary components of ground substance?
Glycosaminoglycans
Proteoglycans
Glycoproteins
What are glycosaminoglycans?
Linear polyanion chains made of repeating disaccharide units. Responsible for the hydrated gel-like nature of the ECM
How do GAGs stain?
Basophilic due to the large number of anions present in the carboxyl, hydroxyl, and sulfate groups.
All GAGs except hyaluronic acid occur covalently linked to linear proteins to form ________.
Proteoglycans
What are 4 major GAGs?
Hyaluronic acid
Dermatan sulfate
Heparin
Keratin sulfate
What is aggrecan?
The predominant proteoglycan in cartilage. Combined with hyaluronic acid it gives cartilage its physical properties.
What makes glycoproteins different from proteoglycans?
The protein moiety predominates.
What do glycoproteins do?
Mediation of cell adhesion and migration.
What are 3 common glycoproteins and where do they exist?
- Fibronectin (surface molecule for adhesion, motility, growth)
- Laminin (basement membranes)
- Chondronectin (cartilage)
What is the difference between dense irregular and dense regular tissue?
Dense irregular = random 3D array.
Dense regular = lined up fibers organized in one direction.
What is the name for the collagen triple helix?
Procollagen
How is tropocollagen formed?
Ends of procollagen are trimmed off and secreted into ECM.
How does type II collagen organize?
It doesn’t really. Its just a mess of weirdly oriented bits, not proper fibers.
What is the major collagen type of cartilage?
Type II
Is type III collagen flexible?
Yes!
Is type I collagen flexible/extensible?
No
Are elastin fibers hydrophilic or hydrophobic?
Hydrophobic
How does elastin appear in its relaxed state?
Curled and aggregated
How big is hyaluronic acid?
HUGE
In the presence of water, GAGs help form a _____ shell.
Hydration
On what do macrophages place the signature epitope/AA sequence of a pathogen?
MHC II receptor
How do plasma cells appear histologically?
Thin basophilic rim. Inside has basophilic granules with a small clear/pale portion inside called the cytocentrum where the golgi apparatus is.
When a mast cell’s IgE encounters a pathogen, what happens?
The many many granules inside fuse with one another and compound exocytosis/degranulation occurs.
Mast cell granules are chemoattractant for…
neutrophils and eosinophils
Although eosinophils themselves are inflammatory they also release ______ substances.
anti-inflammatory
