Connective Tissue Flashcards
What is the classification of connective tissue?
What is Mesenchyme? (3)
- Primitive connective tissue
- Found in the embryo
- Formed through proliferation and migration of the
mesoderm
What does mesenchyme contain? (4)
- Contains spindle-shaped cells with processes
- Gap junctions connect processes to adjacent cell
- Ground substance is viscous
- Sparse and fine collagen and reticular fibers
What does mesenchyme gives rise to? (4)
o Connective tissue
o Muscle
o Vascular and urogenital systems
o Serous membranes
What does mucous connective tissue contain? (4)
- Present in the umbilical cord
- Gelatin-like extracellular matrix (Wharton’s Jelly)
- Contains spindle-shaped cells
- Thin, wispy collagen fibers
Components of connective tissue: (3)
- Cells
- Fibers
- Ground substance
What is Loose/areolar connective tissue? (4)
- Cellular connective tissue with thin and sparse collagen fibers
- Abundant and viscous ground substance and occupies more volume than fibers
- Responsible for diffusion to and from small vessels
- Initial site of immune reaction
What is the location of Loose/areolar connective tissue?
Lamina propria of mucosa (beneath the epithelium)
What is Dense irregular connective tissue? (4)
- Contains mostly connective tissue fibers
- Cells are sparse, mainly fibroblasts
- Little ground substance present
- Resistant to stretching, distension and tearing
What is the location of Dense irregular connective tissue? (2)
o Submucosa of hollow organs
o Reticular/deep dermis layer of the skin
What is Dense regular connective tissue? (3)
- Parallel, densely packed collagen fibers
- Little ground substance present
- Cells are packed and aligned between fiber bundles
What is the location of Dense regular connective tissue? (3)
o Tendons
- Fibroblasts are called tendinocytes
- These cells are surrounded by a specialized ECM separating it from loadbearing collagen
o Ligaments
- Some ligaments of the spinal column have abundant elastic fibers
- Called elastic ligaments
o Aponeuroses
- Fibers are parallel in each sheet
- The sheets of fibers are layered perpendicularly
What are collagen fibres? (5)
- Most abundant fiber types
- Flexible with high tensile strength
- Stains with eosin
- Each collagen molecule is a triple helix of a chains and is non-branching
- Subunits are collagen fibrils forming a banding pattern
What are collagen fibres synthesized by? (5)
Synthesized by:
o fibroblasts
o chondrocytes
o osteoblasts
o pericytes in blood vessels
o epithelial cells (for basement membrane)
What are elastic fibres? (5)
- Allow tissues to respond to stretch and distension
- Thinner than collagen fibers
- Arranged in branching pattern to form a 3D network
- Interwoven with collagen fibers to limit distensibility and prevent tearing
- Unusual polypeptide backbone with random coiling
What are elastic fibres synthesized by?
- Synthesized by fibroblasts and vascular smooth muscles
What are reticular fibres? (3)
- Provide framework for cellular constituents of tissues and organs
- Composed of type III collagen with a banding pattern
- Branched, but do not bundle to form thick fibers
Reticular fibres have _______(stain silver) staining.
- Argyrophilic
Where are reticular fibres located in loose connective tissue?
o Boundary of connective tissue and epithelium
o Surrounding adipocytes, small blood vessels, nerves and muscle cells
Reticular fibres are prominent in _____ healing and ____ formation.
wound
scar
What are reticular fibres synthesized by? (4)
o Reticular cells in haemopoietic and lymphatic tissue
o Fibroblasts
o Schwann cells of peripheral nerve endoneuria
o Smooth muscle cells in tunica media of blood vessels and muscularis of alimentary canal
What is the function of the Extracellular Matrix? (4)
- Provides mechanical and structural support
- Influences extracellular communication
- Functions as a biochemical barrier
- Regulates metabolic functions of surrounding cells
What is the ground substance? (2)
- Viscous, clear, colourless, transparent, amorphous, slippery with high water content
- Supports, surrounds and binds all connective tissue cells and fibers
What is the ground substance composed of? (3)
- Composed of specialized proteins and carbohydrates:
o Proteoglycans
o Multiadhesive glycoproteins
o Glycosaminoglycans (GAGs)
What is the difference between Resident cells and Wandering/transient cells?
What are fibroblasts? (2)
- Principal connective tissue cell
- Synthesize all 3 types of fibres and complex carbohydrates of ground substance
What is the morphology of fibroblasts? (3)
o In H&E staining, only the nucleus is visible as an elongated disc
o Processes extended out of the cell in all directions
o Prominent rough endoplasmic reticulum and Golgi apparatus
What are macrophages? (4)
- Phagocytotic cells derived from monocytes
- Kidney-shaped nucleus present
- Cytoplasm contains many lysosomes
- Difficult to identify
What are adipocytes? (3)
- Stores neutral fat
- Produces a variety of hormones, inflammatory mediators and growth factors
- Flat, squashed nucleus
What are mast cells? (3)
- Develop in bone marrow and differentiate in connective tissue
- Large ovoid cell with spherical nucleus
- Cytoplasm filled with large, intensely basophilic granules
What do granules in mast cells contain? (2)
- Granules contain:
o Histamine (causes allergic reactions)
o Heparin (anticoagulant)
