Connective tissue Flashcards by Lindsay Thomson

What are the 3 fiber types of the ECM? How do they stain?

Collagen
Reticular fibers
Elastic fibers

All stain eosinophilic

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Bundles of collagen fibrils make up a single collagen _____.

Fiber

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What cells produce the matrix of connective tissue?

Fibroblasts

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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.

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What type of collagen makes up reticular fibers?

Type III

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What does the fine network of reticular fibers in the liver do?

Bind the connective tissue (stroma) to the parenchymal cells.

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What type of fiber stains black with a Verhoeff’s stain?

Elastin fibers

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Where do you find elastic fibers?

Surrounding blood vessels

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Who are adipocyte organized?

Surrounded in clumps of septa - flat plates of dense connective tissue - that carry blood vessels.

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What cell type is unilocular? Multilocular?

Unilocular = white cells 
Mulitlocular = brown

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What is the function of brown cells?

Generate heat

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What shape do fibroblasts have?

Fusiform

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What are the type of general connective tissue?

Loose (areolar)

Dense irregular

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What are the types of special connective tissues?

Dense regular
Bone
Cartilage
Reticular
Adipose
Blood

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Loose connective tissue has ____ fibers and _____ cells. Dense irregular connective tissue has _____ fibers and _____ cells.

Thin, many

Thick, few

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What do mesenchymal stem cells give rise to.

Fibroblast
Chondroblast
Osteoblast
Reticular cell
Adipocyte

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What are fibrocytes?

Fibroblasts residing in older established connective tissue that his much lower levels of activity.

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What is the primary fiber type surrounding adipocytes?

Reticular fibers

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What is in the interior of an adipocyte?

A single lipid droplet that can grow or shrink

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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.

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Phagocytic activity of macrophages is mediated by what?

Immunoglobulins and the serum complement system.

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Macrophages have matured what what hematopoietic cell

Monocyte

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What is the life cycle of a macrophage?

40 hours in circulation-> several months or more in the tissue and can still undergo mitosis

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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.

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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?

1. Fibronectin (surface molecule for adhesion, motility, growth) 2. Laminin (basement membranes) 3. 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?

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