CT Flashcards
What makes up connective tissue cells?
Resident cells and wandering cells
What 2 things make up the extracellular matrix?
Fibers and ground substance
What is connective tissue?
Comprises a diverse group of cells within a tissue-specific extracellular matrix (ECM)<br></br><img></img><img></img>
What makes up the resident cells?
Fibroblasts
Macrophages
Adipocytes
Mast cells
Adult stem cells
What makes up wandering cells?
Lymphocytes
Plasma cells
Neutrophils
Eosinophils
Basophils
Monocytes
What makes up fibers in the extracellular matrix?
Collagen fiber system (collagen fibers, reticular fibers)Elastic fiber system
What makes up ground substance?
GAGs
Proteoglycans
Structural glycoproteins (fn, laminin)
Water
Functions of connective tissues
Support: provides support and connections, (e.g. tendons and ligaments)
Defense: the site of inflammatory and immune reactions, physical barrier
Nutrition:
resevoir for water & electrolytes,
stores energy as triglycerides (adipocytes),
supports blood vessels,
passageway for nutrients and gases
Types of connective tissue
Embryonic CT (disappears after birth)
CT proper - divides into loose CT and dense CT (dense CT divides into regular and irregular)
Specialized CT (bone, cartilage, adipose tissue)
Loose/Areolar CT
Loosely arranged cells/ground substance (more)/ fibers
Supports epithelial tissue, surrounds blood vessels, fills spaces between muscles.
Diffusion of oxygen/carbon dioxide and nutrients/wastes, inflammatory and immune reactions, provides structural support
Dense CT
Prominent fibers, little ground substance
Very dense fibers, shows up red (collagen) in H&E
Dense regular CT
Fibers arranged in orderly parallel bundles
Tendons, ligaments, cornea
Transmit force of muscle contraction
Attach muscles to bones
Protection
Dense irregular CT
Collagen is randomly ordered
Seen in the skin, GI tract
Provides tensile strength
Protection
Collagen fiber system includes what?
Collagen fibers
Reticular fibers
Both of these won’t stain will in H&E staining, and will use a special staining
Collagen is the thicker line, elastic fibers are the thinner blue line
Details about collagen fibers
Most abundant type
Flexible yet high tensile strength
Wavy structures
Variable width
Collagen synthesis
Mainly in fibroblast cells
Transcription: The gene for collagen is transcribed in the nucleus, producing mRNA.
Polypeptide Synthesis: mRNA is translated into a collagen polypeptide (procollagen) in the rough ER (RER). It includes repetitive Gly-X-Y sequences, with post-translational modifications like hydroxylation, which requires Vitamin C.
Golgi Apparatus: The procollagen is further modified and assembled into larger structures.
Extracellular Processing: Procollagen is secreted outside the cell and processed into tropocollagen.
Collagen Fiber Formation: Tropocollagen aggregates to form collagen fibers and networks, providing structure to tissues.
Scurvy
Vitamin C (ascorbic acid) is a required cofactor for the addition of hydroxyl groups to proline and lysine residues
A deficiency of water-soluble vitamin C leads to the development of scurvy, characterized principally by bone disease in growing children and by hemorrhages and healing defects in both children and adults
Structure of collagen fibers
Procollagen Subunit: Collagen begins as smaller units called procollagen, which have overlapping and gap regions.
Collagen Fibril: Procollagen subunits come together to form collagen fibrils. These fibrils have a repeating pattern, which is why you see gaps and overlaps.
Collagen Fiber: Several collagen fibrils bundle together to form thicker collagen fibers, which give tissues their strength.
Collagen fibers are thicker than elastic fibers because of the bundling of fibers