4,5 Connective Tissue Flashcards by naynesh patel

Components of ECM in CT.

GAGS, water, ions, proteoglycans, glycoproteins, enzymes.

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Main cells in CT.

Fibroblasts

Synthesis and digestion of all ECM components

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A function of GAGs in ECM of CT.

Bind to high quantity of water therefore effect metabolism

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Function of glycoproteins in ECM of CT?

Modulate cells TO ECM connection

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CT primary functions?

Cranes shoot my pigs tired dr
Connection of different tissues
Structural support
Medium of transport - met diff
Protection of organs
Trophic function
Defence functions
Repairation

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ECM Fibrially components?

Collagen, reticular fibres, elastic fibres

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2 types of cells in CT?

Resident remain in CT
Fibroblats, adipocytes, pericytes, mast cells

Transient temp in CT
Macrophages/histocytes, leukocytes, plasma cells,granulocytes

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Fibroblast to fibrocyte located in?

Loose CT - Adipose, areolar, reticular

Dense CT - Regular, Irregular, Elastic

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Chrondroblasts -> chrondrocytes present in?

Hyaline, elastic, fibrocartilage.

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Fibroblasts contain high amount of?

Golgi and RER.

Formed from Undifferentiated mesenchymal cells

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Inactive fibroblasts?

Flattened more electron dense nucleus therefore greater amount of heterochromatin.
Less protein synthesis
Activated by polypeptide activates.

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Defence functions of macrophages? Which differentiate from monocytes. What else differentiates from monocytes?

Antigen presenting cell involved in Immune response.
Phagocytosis - degradation of debris, ecm components, damaged/aged cells

Osteoclast

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What do macrophages secrete?

How do macrophages go from inactive (fixed) to active?

Cytokines and enzymes

Removal of attached collagen fibres with small finger like projections

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Life span of macrophage?

2 months

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Inactive fixed macrophage?

Kidney shaped nucleus, 19-30um in diameter, spindle/stellate shape.

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Macrophages are present in….and increase in no. during…

Inflammation

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What are histocytes?

Macrophages specialised in different types of cells

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Name type of histocyte in each organ?

Liver, spleen, peritoneal cavity, lung, bone, CNS

Kuppfer cells
Red pulp cells
Perotioneal macrophages
Dust cells 
Osteoclasts
Microglia

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Adipoctyes structure?

Thin cytoplasm and nucleus
Lipid droplet (liposome) dissolved

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Leukocytes increase during inflammation. Name three types?

Granulocytes.

Neutrophils, eosinophils, basophills (similar to mast cells except circulate in the blood)

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How neutrophil from blood into CT?

Diapedisis 
Bind to glycoprotein on endothelial cell surface
Form pseudopodia (polymerisation of actin filaments)
Move between endothelial cells

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Mast cell structural feature?

Large no of granules containing histamine, heparin, proteases.
20-30um on EM.

Ig receptors

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Function of IG E receptors on mast cells?

Inflammatory process
Immediate hypersensitivity reaction - first exposure become sensitive. Second exposure primary and secondary (phospholipids - arachitonic acid) released.

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Plasma cell life span and differentiate from?

Diameter?

B lymphocytes
2-4 weeks
20um

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Plasma cells have large no, of ... To produce immunoglobins?

RER

Plasma cells involved in ...

antibody synthesis and secretion (constitutive) continuous.

Main constituents of collagen?

Proline, glycine, hydroxyproline

Collagen in EM structure starting from a chain?

``` Single A chain A1-A2 helix Tropocollagen Microfibrils Fibrils ```

Collagen extra EM features?

Tropocollagen head to tail arrangement. Specific lateral arrangement. Collagen striated - dark = gaps and lacuna, stain allowed to pass thru. - length of lacuna and overlapping region (light) 64nm

Length of 1 a chain?

95kDa there 3 a chain in a helix = 285kDa

Which cells synthesise collagen and outline 8 steps?

Fibro, chrondro, osteo - blasts Intracellular: Transcription, translation, hydroxylation, glycosylation, pro collagen form helix, secretion of procollagen by TGN. Extracellular: cleavage if pro-peptides form tropocollagen molecules, self assembly - tropocollagen form collagen fibrils

Importance of cross links?

Improve strength | Not easily digested by enzymes and not removed

Importance of hydroxylation of proline and glycine in RER?

Form specific AA residues - form lateral cross-links

Collagen maturation (sif)

Stronger than steel, inelastic, flexible

Which processes collagen synthesis occurs in RER

Translation of procollagen Hydroxylation Glycosylation Procollagen triple helix formed

Relationship between reticular fibres and collagen?

Different arrangement and length of collagen - similar chemical properties

Degradation of collagen 2 methods

1) fibroblasts undergo phagocytosis - phagosome - lysosome - residual body 2) MMP - Matrix metalloproteinases - these include collagenases (degrade type 1,2,3,10 collagen) - synthesised by cancer cells, fibroblasts, chondrocytes, neutrophils, macrophages, monocytes, epithelial cells (keratinocytes).

Which type of MMP do cancer cells produce?

Membrane-type mmp | Potent peri cellular fibrolytic activity

What degrades elastin, type 4 collagen and laminin?

Macrophage metalloelastases

What are collagen crimps?

Waves in tendons 50um long. | Relationship between structure and biomechanical properties.

Reticular fibres organs?

Liver, lymph nodes, spleen, bone marrow

Retucular fibre stain?

High carb - silver stain - argyrophillic fibres

Reticular fibres structural info?

Type 3 collagen 0.5-1.0um in diameter. Loose 3d network. Parallel fibrils form reticular fibre

How much is dry weight is collagen?

30%

Macrophages - function of release of cytokines?

Stimulate immune response

Collagenopathy most common in type 3 collagen?

Ehlers-danlos syndrome. Pathology : defective procollagen peptidase. Non helical procollagen ends. Defective collagen fibrils Symptoms : hyper-elasticity of skin. Joint dislocation

Marfan syndrome?

``` Protein fibrillin 1 deficiency. Therefore elastin fibre irregularity. Defects in blood vessels. May lead to aneurysm of Aorta. Patients tall, skinny, shrimpy ```

5 pathologies associated with MMPs?

Wound healing, inflammation, atherosclerosis, tumour invasion, fibrosis

MMP | What stimulates cell to produce pro MMP - via enzymes - active MMP leading to degradation of ECM?

Growth factors and cytokines. MMP cause ECM remodelling.

What do gelatinases degrade?

Denatured collagen, fibronectin, elastin, laminin.

Where are elastin fibres found?

Lungs, blood vessels ( marfan syndrome ), bladder, skin In grazing animals - nuchal ligament

Elastin fibres what colour stain?

Black lines

Characteristics of elastic fibres?

Elastic Stretched 150% of resting length Non striated Maybe branched - anastomosed - form a network

Elastic fibres structure?

Amorphous - elastin Microfibril component - fibrilin sheets Elastin = core

What 2 AA allows covalent bonding between elastin molecules?

Desmosine and isodesmosine. Specific AA to elastin. Derived from. 4 lysine residues.

Name the 4 main structural glycoproteins in CT?

Fibronectin Laminin Entactin Nidogen

Fibronectin function in CT/ECM?

Binding site for ecm components | Recptors on cell membrane surface

Proteoglycans structure?

Monomer - GAGs attached to central protein | Covalently linked to hyaluronic acid

Function of proteoglycans in ecm of ct?

Form proteoglycan aggregates - bind to water and collagen | Covalently linked to hyaluronic acid

Laminins size and function?

800kda in the bm | Regulate interaction between ecm and cell

Function of SPARC?

Regulate cell cycle | Modulate growth factors and cell-ecm interaction.

When is sparc high produced highly?

Tissue remodelling

Sparc pathogensis

Cell detached from ECM components. Fibrosis. Tumour occurs. May metastasise into blood.

Sparc, where found in cell?

Nuclear matrix of proliferatingcytosol in neurons

3 types of connective tissue (broad terms with subtypes)?

Proper - dense, reg/irregular, loose, adipose, reticular, elastic, Supportive - bone, cartilage Fluid - blood and lymph