Connective Tissue Cells Quiz

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Questions and Answers

Which of the following best differentiates between permanent and wandering cells in connective tissue?

Permanent cells reside and function within the connective tissue, whereas wandering cells migrate into and out of connective tissue. (correct)

Permanent cells are characterized by their large, prominent nuclei, while wandering cells typically have more compact nuclei.

Permanent cells are primarily involved in immune responses, while wandering cells provide structural support.

Permanent cells are derived from the mesoderm, while wandering cells originate from the ectoderm.

Residual bodies observed within macrophages are most likely indicative of which cellular process?

The accumulation of indigestible material of phagocytosis. (correct)

Rapid cell division and differentiation into specialized cell types.

Active secretion of proteins and mucopolysaccharides into extracellular matrix.

The synthesis of new protein fibers, such as collagen, for matrix maintenance.

Which of the following cells are primarily responsible for the production of antibodies in connective tissue?

Mast cells

Eosinophils

B lymphocytes (correct)

Neutrophils

A cell found in connective tissue is observed to possess numerous granules containing histamine and heparin. Is most likely which?

Mast cell Signup and view all the answers

In terms of histological structure and location, how do mast cells and basophils differ from each other?

Mast cells are typically found in connective tissue, while basophils are mainly found circulating in blood. Signup and view all the answers

Which of the following connective tissue types is characterized by a gelatinous matrix rich in hyaluronan and is primarily found in the umbilical cord?

Mucous connective tissue Signup and view all the answers

What is the primary function of Mesenchymal cells found in the embryo?

Differentiate into multiple cell types to form various tissues. Signup and view all the answers

Which of the following is a primary characteristic of dense regular connective tissue?

Primarily composed of collagen fibers oriented in a single direction Signup and view all the answers

Which of these cell types is considered a resident cell of connective tissue?

Fibroblasts Signup and view all the answers

Which of the following best describes the function of dense irregular connective tissue?

Resisting forces from various directions Signup and view all the answers

What is the main difference between fibroblasts and myofibroblasts?

Myofibroblasts have contractile properties, while fibroblasts lack these. Signup and view all the answers

Which of the following is typically found in the ground substance of connective tissue?

Glycosaminoglycans (GAGs) Signup and view all the answers

Which of the following is NOT classified as a wandering cell in connective tissue?

Histiocyte Signup and view all the answers

Where is dense irregular connective tissue typically found?

The submucosa of the GI tract and the dermis Signup and view all the answers

What is the primary role of mast cells in connective tissue?

Initiating an immune response by releasing chemicals like histamine Signup and view all the answers

Which of the following is a function of pericytes in connective tissue?

Regulation of local blood flow and vessel permeability Signup and view all the answers

Which of the following cell types is NOT considered a resident connective tissue cell?

Erythrocytes Signup and view all the answers

The transcription of mRNA for collagen biosynthesis occurs in which cellular compartment?

Nucleus Signup and view all the answers

What is the immediate precursor to pro-collagen after translation?

Pre-pro-polypeptide chain Signup and view all the answers

Which of the following is NOT a post-translational modification that occurs in the rough endoplasmic reticulum (rER) during collagen biosynthesis?

Formation of disulfide bonds Signup and view all the answers

What is the role of vitamin C in collagen biosynthesis?

It is a cofactor for enzymes involved in hydroxylation of lysine and proline residues. Signup and view all the answers

What is the immediate structural consequence of the hydroxylation and glycosylation of pro-a-chains?

Twisting into a triple helix Signup and view all the answers

In which cellular compartment does the packaging of pro-collagen into secretory vesicles take place?

Golgi apparatus Signup and view all the answers

What is the role of ribosomes in collagen biosynthesis?

They are the site of translation of mRNA into polypeptide chains. Signup and view all the answers

A defect in which process would directly prevent the formation of the triple-helix structure of collagen?

Hydroxylation of proline and lysine residues Signup and view all the answers

After the pre-pro-polypeptide enters the rER and undergoes modifications, what is the next structure formed?

Pro-collagen Signup and view all the answers

What is the fate of inert particles, such as inhaled carbon, after digestion?

They persist in cytoplasm as residual bodies. Signup and view all the answers

Which of the following cells are NOT considered resident connective tissue cells?

Eosinophils Signup and view all the answers

Which connective tissue cell type is directly associated with immune response and can produce antibodies?

Plasma cells Signup and view all the answers

What is TRUE about mast cells in connective tissue?

They are involved in the inflammatory response. Signup and view all the answers

Which type of adipose tissue is primarily involved in energy storage and insulation?

White Adipose Tissue (WAT) Signup and view all the answers

What distinguishes myofibroblasts from typical fibroblasts at the structural level?

Myofibroblasts have a moderate amount of rER. Signup and view all the answers

What role do myofibroblasts play in wound healing?

They assist in the contraction of wounds. Signup and view all the answers

Which cell type shares characteristics with myofibroblasts but lacks an external lamina?

Adipocytes Signup and view all the answers

What type of cell is primarily responsible for phagocytosing antibody-coated red blood cells?

M1 macrophages Signup and view all the answers

What microscopic feature is observed in spindled myofibroblasts?

Vesicular nuclei Signup and view all the answers

What distinguishes the ultrastructure of myofibroblasts from smooth muscle cells?

Similarities in filament characteristics Signup and view all the answers

Which resident connective tissue cell is NOT mentioned in relation to myofibroblasts?

Chondrocytes Signup and view all the answers

Which component is fused with lysosomes to form a phagolysosome during macrophage activity?

Phagosome Signup and view all the answers

What characteristic of macrophages is depicted in the scanning electron microscope image?

Engulfing antibody-coated red blood cells Signup and view all the answers

What distinguishes the arrangement of myofibroblasts in tissue?

Loosely arranged spindle cells Signup and view all the answers

Study Notes

Connective Tissue Overview

Connective tissue is one of the four basic tissue types
It provides structural and metabolic support to organs and other tissues
Functions include support (structural and mechanical), packing (fills spaces), storage (energy, water, electrolytes), transport (nutrients and metabolic wastes), repair (matrix and fibers), and defense (phagocytosis or antibodies)

Connective Tissue Structure

Composed of cells (resident and wandering) and extracellular matrix
Resident cells: fibroblasts, adipocytes, macrophages, mesenchymal cells, mast cells
Wandering cells (transient): lymphocytes, plasma cells, eosinophils, basophils, neutrophils, monocytes
Extracellular matrix: protein fibers (collagen, elastic, reticular) and ground substance (amorphous)

Connective Tissue Classification

Embryonic Connective Tissue: mesenchyme, mucous connective tissue (Wharton's jelly)
Connective Tissue Proper: loose (areolar), dense regular, dense irregular
Specialized Connective Tissue: cartilage, bone, adipose tissue, blood, hemopoietic tissue, lymphatic tissue

Learning Objectives

Describe histological characteristics common to connective tissue
List components (cells, ground substance, fibers) of connective tissue
Describe structure of each cell type and correlate with functions
Describe structural organization of loose (areolar), dense regular, dense irregular, embryonic and adipose tissues
Differentiate between embryonic, loose, dense regular and dense irregular connective tissues based on images
Describe the synthesis, secretion and assembly of collagen fibers
Describe the three most common extracellular fibers (collagen, elastic, reticular)
State locations of collagen, elastic and reticular fibers
List common sites of collagens I-VI and describe the consequences of deficiencies
Describe biochemical structure and functions of glycosaminoglycans (GAGs), proteoglycans and glycoproteins
Identify macrophages, mast cells, eosinophils, neutrophils, lymphocytes, plasma cells, fibroblasts, pericytes, and adipocytes in microscopic sections
Describe functions of mesenchymal stem cells and myofibroblasts
Differentiate between permanent and wandering cell types
Identify residual bodies in macrophages
Describe functions of B and T lymphocytes, neutrophils, mast cells, basophils, plasma cells, and eosinophils
Differentiate between mast cells and basophils

Connective Tissue Proper: Loose (Areolar) Tissue

Predominantly ground substance, few cells (mostly fibroblasts).
Cells are primarily migratory.
Key locations: beneath epithelial layers, around glands and smallest blood vessels.
Supports microvasculature, nerves and immune cells.

Connective Tissue Proper: Dense Regular Tissue

Primarily type I collagen fibers and fibroblasts aligned in parallel.
Provides resistance to prolonged or repeated stresses
Poorly vascularized: Slow repair
Found in tendons, ligaments, aponeuroses.

Connective Tissue Proper: Dense Irregular Tissue

Contains mostly collagen fibers, not as much ground substance.
Bundles of fibers oriented in various directions.
Provides resistance to tearing when stretched.
Found in the reticular layer of skin dermis and submucosa of GI tract

Resident Connective Tissue Cells

Fibroblasts: Primary cells of connective tissue; synthesize collagen, elastin, and reticular fibers; and complex carbohydrates of ground substance (GAGs); show morphological variation based on activity level; fibroblast or fibrocyte.
Myofibroblasts: Fibroblasts with some characteristics of smooth muscle cells (e.g., contractile filaments); implicated in wound contraction.
Macrophages (Histiocytes): Phagocytic cells; derived from monocytes; can be seen in clusters or as large phagocytic cells with residual bodies.
Adipocytes: Store energy in form of triglycerides; unilocular (fat cells): large single droplet in cytoplasm of mature cells; multilocular (brown fat): presence many small lipid droplets; involved in energy metabolism, particularly in infants for heat generation.
Mast Cells: Granular cells; originate from bone marrow basophil/mast cell precursors; part of innate immune system, respond to various stimuli and release inflammatory mediators (e.g., histamine, tryptase).
Undifferentiated Mesenchymal Cells/Pericytes: Can differentiate into other cell types—like fibroblasts or myofibroblasts—during injury repair, located around blood vessels, crucial in neovascularization and wound healing

Wandering Cells of Connective Tissue

Lymphocytes: Primarily involved in immune responses (B cells produce antibodies; T cells mediate cellular immunity; NK cells destroy virus-infected and tumor cells).
Plasma Cells: Derived from B lymphocytes; produce antibodies.
Eosinophils: Granulocytes that play a role in allergic reactions and parasitic infections.
Basophils: Granulocytes that release histamine, involved in allergic reactions and inflammation.
Neutrophils: Granulocytes that are the first responders to infection, exhibiting phagocytic activity against pathogens.
Monocytes: Phagocytic cells; differentiate into macrophages, which function in antigen presentation and immune defense.

Collagen Biosynthesis

Transcription of mRNA for pro-a1 and pro-a2 chains in nucleus.
Translation in cytoplasm, producing pre-pro-polypeptide chains.
Post-translational modifications: Signal peptide removal, hydroxylation of specific amino acids (requires vitamin C), and glycosylation.
Assembly into procollagen molecules in RER.
Transport of procollagen to the Golgi apparatus.
Procollagen cleavage (removal of terminal propeptides) outside the cell.
Assembly of tropocollagen molecules into fibrils.
Cross-linking of tropocollagen molecules to form collagen fibrils.

Collagen Breakdown

Proteolytic degradation: MMPs break down ECM.
Phagocytic degradation: Macrophages and fibroblasts engulf and degrade collagen.

Collagen Fiber Types

Type I: Most common; found in bone, tendon, dermis.
Type II: Important in cartilage.
Type III: Forms reticular fibers; found in supporting tissues like those surrounding blood vessels and lymphatic tissue.
Type IV: Major component of basement membranes.

Elastic Fibers

Thinner than type I collagen fibers.
Form sparse networks in tissues that undergo regular stretching or bending.
Synthesized by fibroblasts and smooth muscle cells.
Consist of elastin molecules arranged in a crosslinked network in an amorphous matrix of the microfibrils
Key locations: ligaments, lungs, blood vessels.

Reticular Fibers

Composed of type III collagen.
Visualized with silver staining (argyrophilic).
Thin, delicate networks that support structures or tissues such as blood vessels and lymph nodes in spleen and bone marrow.

Ground Substance

Viscous, amorphous component of connective tissue.
Mostly composed of proteoglycans, GAGs, and multiadhesive glycoproteins.
Functions: Supports cells, tissues fluids, medium through which molecules can diffuse, and site for cell adhesion.
Usually lost during tissue fixation.

Specific Cell Types

Mast cells: key role in inflammation and allergic reactions.
Pericytes: undifferentiated mesenchymal cells associated with capillaries and venules, function in neovascularization and wound healing.

Other Important Tissue Components

Mucous connective tissue (Wharton's jelly): specialized type of embryonic connective tissue rich in ground substance, present in the umbilical cord, helping to support and cushion the developing fetus; also has regenerative potential in regenerative medicine.
Adipose tissue: stores energy in the form of triglycerides and cushions vital organs; categorized into white and brown adipose tissue.
White adipose tissue (WAT): predominant in adults, primarily stores energy, cushions organs, regulates endocrine function (hormones like leptin.
Brown adipose tissue (BAT): predominantly found in fetuses and newborns; primarily for heat generation via metabolism
Lymphoid tissue: specialized connective tissue that supports lymphocytes and other immune cells; an integral part of the body's immune system.

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Description

Test your knowledge on the various types of cells found in connective tissue with this quiz. You'll explore the differences between permanent and wandering cells, the roles of macrophages, and the characteristics of different connective tissue types. Challenge yourself on the histological structures and functions of these important biological components.