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Questions and Answers
What type of tropocollagen is primarily found in reticular fibers?
What type of tropocollagen is primarily found in reticular fibers?
- Type III (correct)
- Type I
- Type II
- Type IV
Which characteristic of elastic fibers is correct?
Which characteristic of elastic fibers is correct?
- They do not resume their original length after stretching.
- They are primarily composed of collagen.
- They can be stretched to about 150% of their original length. (correct)
- They contain no structural matrix.
What components make up the matrix of elastic fibers?
What components make up the matrix of elastic fibers?
- Microfibrils and an amorphous matrix (correct)
- Elastin only
- Collagen and elastin
- Polysaccharides and proteins
Which statement correctly describes proteoglycans in the ground substance?
Which statement correctly describes proteoglycans in the ground substance?
What structural feature distinguishes type IV tropocollagen?
What structural feature distinguishes type IV tropocollagen?
What is the tensile force necessary to tear human collagen fibers?
What is the tensile force necessary to tear human collagen fibers?
Which type of fibers are typically not visible in histological sections without special stains?
Which type of fibers are typically not visible in histological sections without special stains?
Which component contributes to the viscosity of the ground substance?
Which component contributes to the viscosity of the ground substance?
What is the primary function of adipocytes?
What is the primary function of adipocytes?
What type of cell differentiates into macrophages after leaving the bloodstream?
What type of cell differentiates into macrophages after leaving the bloodstream?
Which statement related to adipocytes is accurate?
Which statement related to adipocytes is accurate?
What is the role of fibroblasts after tissue damage?
What is the role of fibroblasts after tissue damage?
How do resting macrophages compare to fibrocytes in connective tissues?
How do resting macrophages compare to fibrocytes in connective tissues?
What happens to an adipocyte when it becomes 'starving'?
What happens to an adipocyte when it becomes 'starving'?
Which structure do reticular cells help form in lymphoid organs?
Which structure do reticular cells help form in lymphoid organs?
What characterizes the cytoplasm of a well-fed adipocyte?
What characterizes the cytoplasm of a well-fed adipocyte?
What is the primary function of collagen fibers in connective tissue?
What is the primary function of collagen fibers in connective tissue?
Which component is NOT typically found in the extracellular matrix of connective tissue?
Which component is NOT typically found in the extracellular matrix of connective tissue?
What are the three main types of fibers found in connective tissue?
What are the three main types of fibers found in connective tissue?
Which of the following is a function of connective tissue?
Which of the following is a function of connective tissue?
What is the embryonic origin of connective tissue?
What is the embryonic origin of connective tissue?
How thick can collagen fibers typically range in diameter?
How thick can collagen fibers typically range in diameter?
What is the name of the spiral-like assembly of three collagen molecules that compose microfibrils?
What is the name of the spiral-like assembly of three collagen molecules that compose microfibrils?
Which of the following accurately describes the organization of tropocollagen within microfibrils?
Which of the following accurately describes the organization of tropocollagen within microfibrils?
What role does hyaluronic acid play in connective tissue?
What role does hyaluronic acid play in connective tissue?
Which of the following is NOT a major glycosaminoglycan mentioned?
Which of the following is NOT a major glycosaminoglycan mentioned?
What is primarily formed by the coiled arrangement of hyaluronic acid and other glycosaminoglycans?
What is primarily formed by the coiled arrangement of hyaluronic acid and other glycosaminoglycans?
How do glycosaminoglycans affect water in connective tissue?
How do glycosaminoglycans affect water in connective tissue?
Which factor contributes to the immobilization of bacteria in the extracellular space?
Which factor contributes to the immobilization of bacteria in the extracellular space?
What distinguishes fixed cells from wandering cells in connective tissue?
What distinguishes fixed cells from wandering cells in connective tissue?
What characterizes fibrocytes in connective tissue?
What characterizes fibrocytes in connective tissue?
What is one effect of the enzyme hyaluronidase produced by some bacteria?
What is one effect of the enzyme hyaluronidase produced by some bacteria?
Study Notes
Connective Tissue
- Most diverse and abundant tissue in the body.
- Consists of cells, fibers, and ground substance.
- Cells can be fixed or wandering.
- Has a common embryonic origin - mesenchyme.
- Main Classes:
- Connective tissue proper
- Cartilage
- Bone tissue
- Blood
Connective Tissue Functions
- Storage of energy
- Protection of organs
- Provision of structural framework for the body
- Connection of body tissues
- Connection of epithelial tissues to muscle fibers
- Supply of hormones throughout the body
- Nutritional support to epithelium
- Site of defense reactions
- Repair of body tissues
Connective Tissue Matrix
- Accounts for the majority of the connective tissue volume.
- Composed of fibers and ground substance.
Connective Tissue Fibers
- Collagen fibers
- Most abundant fiber type.
- Provide strength to connective tissue.
- Composed of collagen fibrils and microfibrils.
- Microfibrils are assemblies of tropocollagen, which is a triple helix of three collagen molecules.
- Different types of collagen exist (I-XXI), with different amino acid content and carbohydrate attachments.
- Type I is the major type in most connective tissues.
- Reticular fibers
- Very delicate and form networks.
- Support individual cells, for example, in muscle and adipose tissue.
- Composed of type III collagen.
- Elastic fibers
- Provide elasticity to connective tissues.
- Composed of microfibrils embedded in an amorphous matrix of elastin.
- Can be stretched to 150% of their original length and return to their original shape.
Ground Substance
- Occupies the spaces between fibers and cells.
- Composed of proteoglycans, water, salts, and other low molecular weight substances.
- Proteoglycans are responsible for its viscous character.
- Glycosaminoglycans:
- Hyaluronic acid: dominant glycosaminoglycan, acts as a backbone for other glycosaminoglycans, found in synovial fluid and vitreous body of the eye
- Chondroitin sulfate, dermatan sulfate, keratan sulfate, and heparan sulfate: attach to the hyaluronic acid backbone.
- The coiled arrangement of hyaluronic acid and other glycosaminoglycans forms domains that create a three-dimensional molecular sieve in the interstitial spaces.
- The ground substance acts as a medium for the diffusion of small molecules and restricts the movement of larger molecules, including microorganisms.
- Hyaluronidase breaks down hyaluronic acid and is produced by some invasive bacteria to penetrate the ground substance.
Connective Tissue Cells
- Divided into fixed cells and wandering cells.
- Fixed cells:
- Fibrocytes (or fibroblasts)
- Fat cells (adipocytes)
- Wandering cells:
- Macrophages
- Monocytes
- Lymphocytes
- Plasma cells
- Eosinophils
- Mast cells
Fibrocytes
- Most common cell type.
- Responsible for the production of fibers and ground substance.
- Resting fibrocytes have a small amount of cytoplasm, while active fibroblasts have many organelles for protein synthesis.
Reticular Cells
- Larger than fibrocytes.
- Form the reticular network in lymphoid organs.
Adipocytes (Fat cells)
- Store lipids.
- Contain a large central lipid droplet.
- Number is determined during fetal and early postnatal development.
- Functions:
- Storage of energy
- Secrete the protein leptin – regulates appetite
Macrophages
- Arises from monocytes.
- Phagocytic cells.
- Responsible for engulfing foreign particles and debris.
Wandering Cells
- Macrophages:
- Engulf pathogens and cellular debris.
- Derived from monocytes.
- Monocytes:
- Precursors to macrophages.
- Lymphocytes:
- Involved in immune responses
- Plasma cells:
- Produce antibodies.
- Eosinophils:
- Fight parasitic infections.
- Mast cells:
- Release histamine and other inflammatory mediators.
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Description
Explore the diverse and vital role of connective tissue in the human body. This quiz covers the main classes, functions, and components of connective tissue, including its matrix and fiber types. Test your understanding of how connective tissue supports and connects various body structures.
