60 Questions
What is the primary function of connective tissue?
Providing and maintaining shape and firmness in the body
What are the three structural components of connective tissue?
Cells, fibers, and ground substance
Which type of protein fibers are found in the connective tissue matrix?
Collagen, reticular, and elastic fibers
What fills the spaces between the collagen and elastic fibers in the connective tissue matrix?
Granular material
What is the primary function of ground substance in connective tissue?
Filling spaces between fibers and surrounding cells
What is the main role of connective tissue as an exchange medium?
Exchanging waste products between cells and the bloodstream
Which cell type is responsible for the production and secretion of the extracellular matrix?
Fibroblasts
Which cell type is involved in phagocytosis and engulfing foreign particles?
Macrophages
Which cell type releases mediators causing vasodilation and increased vascular permeability?
Mast cells
Which cell type is characterized by granules containing mediators such as histamine and proteases?
Mast cells
Which cell type is derived from monocytes that circulate in the blood?
Macrophages
Which cell type is responsible for paracrine secretion of leukotrienes causing increased smooth muscle contraction and mucus production?
Mast cells
Which cell type is involved in antibody production and mediates immunity?
Plasma cells
What is the most common protein in the human body, providing strength and structure to various tissues?
Collagen
Which leukocytes contain basophilic granules, mediate inflammatory processes, and phagocytose AG-AL complexes?
Eosinophils
Which type of collagen is the most abundant and is composed of two alpha1 and one alpha2 peptide chains?
Collagen I
Which leukocytes migrate from the bloodstream into tissues through diapedesis?
Eosinophils
What is the main function of fibroblasts in relation to collagen synthesis?
Synthesize tropocollagen
What type of fibers provide structure to the mesentery?
Collagen fibers
How are collagen bundles observed in polarizing microscopy?
With a dark color in superimposed regions
Which staining procedure makes elastic fibers appear darker in the skin dermis?
Staining procedures other than H&E
What are proteoglycans composed of?
Core protein and covalently bound glycosaminoglycans (GAGs)
What is the main function of GAGs in proteoglycans?
They are highly hydrated and contain hydrophilic polyanions
What distinguishes glycoproteins from proteoglycans?
Globular protein molecules with covalently attached branched chains of monosaccharides
How are collagen fibrils assembled, resulting in cross striations with alternating dark and light bands in electron microscopy?
They are assembled with a regular, overlapping pattern
What initiates the degradation of collagen fibers?
Collagenases
What does Type III collagen form?
Reticular fibers
What is the role of oxytalan fibers in elastic fibers?
They form a network that supports elastin, allowing for its elastic properties
What results in the rupture of the arterial wall?
Deficiencies in collagen type III
Which process involves the formation of polypeptide chains, injection as preprocollagen, and subsequent hydroxylation and glycosylation to form procollagen?
Collagen synthesis in RER
Which cell type is involved in antibody production and mediates immunity?
Plasma cells
What is the most common protein in the human body, providing strength and structure to various tissues?
Collagen I
Which leukocytes contain basophilic granules, mediate inflammatory processes, and inactivate histamines and leukotrienes?
Eosinophils
What is the primary function of ground substance in connective tissue?
Support and attachment
What initiates the degradation of collagen fibers?
Matrix metalloproteinases (MMPs)
Which process involves the formation of polypeptide chains, injection as preprocollagen, and subsequent hydroxylation and glycosylation to form procollagen?
Collagen synthesis
How are collagen fibrils assembled, resulting in cross striations with alternating dark and light bands in electron microscopy?
Collagen synthesis involves the formation of polypeptide chains
What initiates the degradation of collagen fibers?
Degradation of collagen fibers can be initiated by collagenases
What does Type III collagen form?
Reticular fibers
Which process involves the formation of polypeptide chains, injection as preprocollagen, and subsequent hydroxylation and glycosylation to form procollagen?
Collagen synthesis
What fills the spaces between the collagen and elastic fibers in the connective tissue matrix?
Ground substance
What are elastin cross-links formed through?
Covalent reactions between lysine residues
What is the main function of proteoglycans in the extracellular matrix?
Act as a structural support for the matrix
What distinguishes glycoproteins from proteoglycans in the extracellular matrix?
Glycoproteins are linear polysaccharides, while proteoglycans are globular proteins
Which type of fibers provide elasticity to the skin dermis?
Elastin fibers
What initiates the degradation of collagen fibers in the connective tissue?
Matrix metalloproteinases (MMPs)
What fills the spaces between cells and fibers in the connective tissue matrix?
Ground substance
What is the primary function of connective tissue as an exchange medium?
To facilitate nutrient and waste exchange
What is the main function of ground substance in connective tissue?
To maintain the viscosity and hydrophilic nature of the extracellular matrix
What initiates the degradation of collagen fibers in connective tissue?
Mast cells releasing histamine and proteases
Which process involves the formation of polypeptide chains, injection as preprocollagen, and subsequent hydroxylation and glycosylation to form procollagen?
Collagen synthesis pathway
What type of fibers provide structure to the mesentery in connective tissue?
Reticular fibers
What is the main function of fibroblasts in relation to collagen synthesis in connective tissue?
Synthesizing and secreting collagen molecules
What are proteoglycans composed of in connective tissue?
Glycosaminoglycanen chains attached to a protein core
What is the primary function of fibroblasts in relation to the extracellular matrix?
Synthesizing and secreting extracellular matrix components
Which type of leukocytes mediate inflammatory processes and phagocytose AG-AL complexes?
Mast cells
What distinguishes quiescent fibroblasts from active fibroblasts?
Smaller size and less active components
Which cell type is characterized by its involvement in phagocytosis and engulfing foreign particles?
Macrophages
What is the main role of mast cells in the inflammatory response?
Facilitating vasodilation and increased vascular permeability
Which cell type releases leukotrienes through paracrine secretion, causing increased smooth muscle contraction and mucus production?
Mast cells
Study Notes
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Collagen fibrils are assembled with a regular, overlapping pattern, resulting in cross striations with alternating dark and light bands in electron microscopy.
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Collagen fibrils are linked together to form larger collagen fibers visible by light microscopy.
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Collagen fibers form larger aggregates, typically of Type I collagen, which are bundled and linked together by other collagens.
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Collagen synthesis in RER involves the formation of polypeptide chains, injection as preprocollagen, and subsequent hydroxylation and glycosylation to form procollagen.
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The removal of signalling sequences from procollagen results in procollagen, which is then transported out of the cell.
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Procollagen is cleaved by proteases to form tropocollagen, allowing for the assembly of collagen fibrils.
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Collagen fibrils spontaneously aggregate to form fibers, and fibers are further reinforced by covalent cross-links between tropocollagen molecules.
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Collagen turnover is generally a slow process, with stable collagen in tendons, ligaments, and periodontal ligaments having a low turnover.
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Degradation of collagen fibers can be initiated by collagenases, which remove the original tropocollagen peptides and allow for further degradation by normal proteases.
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Collagen fibers are often organized into bundles in various parts of the body.
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Collagen fibers are mainly composed of Type I collagen, which is visible as acidophilic fibers in connective tissues.
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Type III collagen forms reticular fibers, which are much thinner (0.5 to 2 µm) and form a loose network in various tissues such as smooth muscles, endoneurium, and blood-forming organs.
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Elastic fibers are composed of three types of fibers: oxytalan, elaunine, and elastin.
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Elastin cross-links are formed through covalent reactions between lysine residues, resulting in desmosine and isodesmosine.
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Elastin fibers are not elastic on their own, but oxytalan fibers form a network that supports elastin, allowing for its elastic properties.
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Elastic fibers stretch easily due to the different ratio of microfibrils to elastin, which is adapted to the local tissue requirements.
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Elastin is a globular molecule that polymerizes to form elastin, an amorphous rubber-like glycoprotein.
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Elastin is made up of a high proportion of glycine, proline, and two unusual amino acids: desmosine and isodesmosine.
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Elastin fibers have a high turnover in areas such as the arterial wall.
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Deficiencies in collagen type III can result in the rupture of the arterial wall.
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Fibroblasts (5-3, 5-4, 5-5) are cells derived from embryonic mesenchyme that synthesize extracellular matrix components such as collagen, elastine, glycosaminoglycan, and multiadhesive glycoproteins.
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Fibroblasts are spindle-shaped cells with large, active nuclei and eosinophilic cytoplasm that tapers off in both directions along the axis of the nucleus. They are responsible for the production and secretion of the extracellular matrix.
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Quiescent fibroblasts, also known as fibrocytes, are smaller cells with less active components and less cytoplasm. They are less active in producing and secreting extracellular matrix components.
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Macrophages (5-6, 5-7, 5-8) are derived from monocytes that circulate in the blood and have an irregular surface and prominent rough endoplasmic reticulum. They are involved in phagocytosis and engulfing foreign particles, as well as releasing lysosomal enzymes to break down the particles.
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Macrophages have well-developed Golgi complexes and numerous lysosomes, which help in the digestion and processing of engulfed particles.
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Mast cells (5-10) are cells found in connective tissue and are characterized by their granules, which contain mediators such as histamine and proteases. They play a role in the inflammatory response by releasing these mediators and causing vasodilation and increased vascular permeability.
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Mast cells have a central, rounded nucleus and are packed with secretory granules. They release their contents through exocytosis in response to stimuli such as antigens or tissue damage.
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Mast cells also release leukotrienes through paracrine secretion, which can cause increased smooth muscle contraction, increased vascular permeability, and increased mucus production.
Test your knowledge of cell biology and immunology with this quiz. Questions cover topics such as phospholipases, leukotrienes, plasma cells, eosinophil chemotactic factor, and adipose cells.
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