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Connective Tissue Overview
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Connective Tissue Overview
Connective Tissue Overview
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1
Question
What is the primary function of connective tissue?
Answer
Connective tissue is specialized to physically support and connect other tissues and maintain the water required for metabolite diffusion to and from cells.
2
Question
How do connective tissues differ from nervous, epithelial, and muscular tissues in composition?
Answer
Connective tissues consist primarily of extracellular material rather than cells.
3
Question
What forms the supportive stroma in most organs?
Answer
Connective tissue proper forms the supportive stroma, which supports the organ's unique functional components or parenchyma.
4
Question
What does the extracellular matrix (ECM) of connective tissue proper usually consist of?
Answer
The ECM usually consists of large protein fibers (collagen fibers and elastic fibers) and nonfibrous areas of unstained ground substance rich in various GAGs and water.
5
Question
From what embryonic form is all adult connective tissue derived?
Answer
All adult connective tissues are derived from an embryonic form of connective tissue called mesenchyme.
6
Question
What is mesenchyme and where does it originate from?
Answer
Mesenchyme is a tissue developing mainly from the middle layer of the embryo, the mesoderm, containing uniformly undifferentiated cells scattered in a gel-like matrix.
7
Question
What are the primary germ layers and what do they form?
Answer
Ectoderm (outermost layer) forms the skin and nerves; Mesoderm (middle layer) forms muscles, bone, cartilage, heart, and blood vessels; Endoderm (innermost layer) forms the lining of the gut, liver, pancreas, gallbladder, and derivatives of the pharyngeal pouch.
8
Question
What is the structure and composition of mesenchyme?
Answer
Mesenchyme consists largely of viscous ground substance with few collagen fibers and a population of undifferentiated cells, generally elongated with large euchromatic nuclei and prominent nucleoli.
9
Question
What are mesenchymal cells?
Answer
Mesenchymal cells are undifferentiated cells surrounded by an ECM that they produced, consisting largely of simple ground substance rich in hyaluronan with very little collagen.
10
Question
What are the main cell types found in connective tissue?
Answer
1. Fibroblasts 2. Adipocytes 3. Macrophages 4. Mast Cells 5. Plasma Cells 6. Other Leukocytes.
11
Question
Describe fibroblasts in connective tissue.
Answer
Fibroblasts (fibrocytes) are the major cells of connective tissue proper, elongated and irregularly shaped with oval nuclei; they synthesize and secrete most components of the ECM.
12
Question
What distinguishes active fibroblasts from quiescent fibroblasts?
Answer
Active fibroblasts have intense synthetic activity, larger and irregularly branched, with abundant cytoplasm and a large euchromatic nucleus, while quiescent fibroblasts are smaller, spindle-shaped, with darker heterochromatic nuclei.
13
Question
What are adipocytes and their function?
Answer
Adipocytes (fat cells) are large cells specialized for the storage of triglycerides (lipid, neutral fats) and serve to cushion and insulate the skin and other organs.
14
Question
What are macrophages and their primary function?
Answer
Macrophages are short-lived cells that differentiate from monocytes and are involved in ECM turnover, phagocytosis of dead cells and debris, and antigen presentation to lymphocytes.
15
Question
How do macrophages change when activated?
Answer
Activated macrophages increase in size, enhance phagocytic capacity, and show increased metabolic and lysosomal enzyme activity.
16
Question
What are multinuclear giant cells?
Answer
Multinuclear giant cells form when macrophages increase in size and fuse, usually found only in pathological conditions.
17
Question
What is the difference between monocytes and macrophages?
Answer
Monocytes are immature cells that circulate in the blood; macrophages are mature cells that have differentiated in connective tissue.
18
Question
What role do macrophages play in tissue damage and inflammation?
Answer
They accumulate in connective tissue via local proliferation and recruitment from blood, playing a crucial role in the early stages of repair and inflammation.
19
Question
What is the mononuclear phagocyte system?
Answer
A family of cells comprised of macrophages along with other monocyte-derived cells, each having different names in various organs.
20
Question
What are mast cells and their primary function?
Answer
Mast cells originate from blood cell precursors, are filled with granules, and release various vasoactive agents and other substances during inflammatory and allergic reactions.
21
Question
What is metachromasia in mast cells?
Answer
Mast cell granules display metachromasia due to the high content of acidic radicals in their sulfated GAGs, allowing them to change the color of some basic dyes.
22
Question
What are the key substances released from mast cell granules?
Answer
Key substances include heparin, histamine, serine proteases, eosinophil and neutrophil chemotactic factors, and cytokines.
23
Question
What is immediate hypersensitivity reaction?
Answer
Allergic reactions promoted by the release of certain chemical mediators in mast cells, occurring within minutes after exposure to an antigen in a sensitized individual.
24
Question
What is anaphylactic shock?
Answer
A dramatic example of immediate hypersensitivity reaction, potentially fatal, triggered by the rapid release of substances from mast cell granules upon re-exposure to an allergen.
25
Question
What are plasma cells and their role in the immune response?
Answer
Plasma cells are differentiated B-lymphocytes that produce antibodies, mediating immunity, with an average lifespan of 10-20 days.
26
Question
How do other leukocytes differ in their function within connective tissue?
Answer
Other leukocytes, besides macrophages and plasma cells, wander through connective tissue, providing surveillance against pathogens and stimulating tissue repair.
27
Question
What is inflammation?
Answer
Inflammation is a vascular and cellular defensive response to injury or foreign substances, characterized by increased blood flow, vascular permeability, and entry of leukocytes.
28
Question
How do leukocytes migrate from the bloodstream into connective tissue?
Answer
Leukocytes leave the bloodstream by migrating between the endothelial cells of venules to enter connective tissue.