Characteristics of Connective Tissue

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Questions and Answers

What is the main function of plasma cells?

To synthesize and secrete immunoglobulin (correct)

To cause allergic reactions

To store fat

To differentiate into multiple cell types

What is unique about the nucleus of a plasma cell?

It is absent

It is centrally located

It is fragmented

It is eccentrically located (correct)

What is the function of mast cells?

To differentiate into multiple cell types

To store fat

To cause allergic reactions (correct)

To synthesize and secrete immunoglobulin

What is the function of fat cells?

To synthesize and store fat Signup and view all the answers

What is the characteristic of the cytoplasm of a plasma cell?

It is basophilic Signup and view all the answers

What is the function of undifferentiated mesenchymal cells?

To differentiate into multiple cell types Signup and view all the answers

What happens to neutrophils and eosinophils after entering connective tissue?

They live for a short time and then die Signup and view all the answers

What is the characteristic of the granules in mast cells?

They are metachromatic and basophilic Signup and view all the answers

What is the primary function of fibroblasts in loose connective tissue?

Synthesize fibers and ground substance Signup and view all the answers

What is the characteristic shape of a fibroblast under light microscopy?

Large, flattened cell with processes Signup and view all the answers

What is the function of a fibrocyte?

Become active fibroblasts for repairing Signup and view all the answers

What is the characteristic feature of a macrophage's cytoplasm under light microscopy?

Acidophilic Signup and view all the answers

What is the main component of ground substance?

Proteoglycans Signup and view all the answers

What is the function of macrophages in terms of immune responses?

Capturing, processing, and presenting antigens to lymphocytes Signup and view all the answers

What is the function of proteoglycans in ground substance?

To allow the passage of nutrients and gases Signup and view all the answers

What type of connective tissue has parallelly-arranged collagenous fibers?

Regular Dense Connective Tissue Signup and view all the answers

What is the term for the process by which macrophages ingest and digest foreign particles and microorganisms?

Phagocytosis Signup and view all the answers

What is the characteristic of brown adipose tissue?

Many small lipid droplets Signup and view all the answers

What is the function of hyaluronic acid in ground substance?

To link subunits of proteoglycans Signup and view all the answers

What is the main component of elastic tissue?

Elastic fibers Signup and view all the answers

What is the characteristic of white adipose tissue?

Single large lipid droplet Signup and view all the answers

What is the distribution of brown adipose tissue?

Neonate and decrease with age Signup and view all the answers

What is the functional feature of collagenous fibers?

Have great tensile strength, but inelastic Signup and view all the answers

What type of collagen is found in reticular fibers?

Type III collagen Signup and view all the answers

What is a characteristic of the cells of connective tissue?

Stellate shape with processes Signup and view all the answers

What is the characteristic of elastic fibers under EM?

Core: elastin-low electron density, Peripheral: microfibril Signup and view all the answers

What type of cells are mast cells and fat cells?

Fixed cells Signup and view all the answers

What is one of the functions of connective tissue?

Extravascular transport of nutrients and waste Signup and view all the answers

What is the origin of all connective tissue?

Mesenchyme Signup and view all the answers

What is the diameter of collagenous fibers?

1-20 μm Signup and view all the answers

What is a type of connective tissue that is not included in the narrow sense of connective tissue?

Cartilage Signup and view all the answers

What type of fibers are argyrophilic?

Reticular fibers Signup and view all the answers

What is a characteristic of the extracellular matrix of connective tissue?

It is composed of fibers and amorphous ground substance Signup and view all the answers

What is a function of the matrix in connective tissue?

Forming a physical barrier to infectious agents Signup and view all the answers

Study Notes

General Features of Connective Tissue

Small number of cells and large amount of extracellular ground substance
Extracellular matrix composed of fibers and amorphous ground substance
All connective tissue originates from mesenchyme - embryonal connective tissue
No polarity
Rich in blood vessels
Basement membrane present

Functions of Connective Tissue

Mechanical support and connection
Extravascular transport of nutrients, wastes, gases, hormones, etc.
Healing, repair, and regeneration
Defense: Matrix forms physical barrier to infectious agents; active in inflammatory responses; reservoir of phagocytic and antibody-producing cells

Mesenchymal Cells

Structure: stellate-shaped with processes, large nucleus with clear nucleoli, and slight basophilic cytoplasm
Function: undifferentiated cell with multiple developmental potential (connective tissue cell, smooth muscle cell, and endothelial cell)

Matrix

Ground substance: amorphous colloidal substance consisting of proteoglycans, multiadhesive glycoprotein, and tissue fluid
Fibers: collagenous, elastic, and reticular fibers

Classification of Connective Tissue

Narrow sense: loose connective tissue, dense connective tissue, adipose tissue, and reticular tissue
Wide sense: includes cartilage, bone, and blood

Loose Connective Tissue (Areolar Tissue)

Cells: fibroblast, macrophage, plasma cell, mast cell, fat cell, and leukocytes (neutrophils, eosinophils, and lymphocytes)
Fibers: three types (collagenous, elastic, and reticular fibers)
Ground substance: same as matrix

Fibroblast

Structure:
- LM: large, flattened cell with processes, large ovoid pale nucleus, and weakly basophilic cytoplasm
- EM: rich in RER, Golgi apparatus, and free ribosomes
Function: synthesizes fibers and ground substance
Fibrocyte: inactive fibroblast, structure and function similar to fibroblast but with less organelles

Macrophage (Histiocyte)

Structure:
- LM: round or ovoid with short blunt processes, small dark nucleus, and acidophilic cytoplasm
- EM: rich in lysosomes, phagosomes, and microfilaments
Function:
- Ingestion and digestion of microorganisms, damaged cells, and particles
- Antigen presentation: capturing, processing, and presenting antigens to lymphocytes, triggering immune responses
- Secretion of various substances (lysozyme, interferon, interleukin 1, etc.)

Plasma Cell

Structure:
- LM: round or ovoid, eccentrically-located nucleus with spot-like heterochromatin, pale staining region, and basophilic cytoplasm
- EM: rich in parallelly-arranged RER, free ribosomes, and Golgi complex
Function: synthesizes and secretes immunoglobulins (antibodies), derived from B-lymphocytes

Mast Cell

Structure:
- LM: round and large, often found near blood vessels, with abundant and coarse basophilic granules
- Cytoplasm contains heparin (anticoagulant), histamine (causes capillary permeability increase, leakage, and smooth muscle contraction), and eosinophil chemotactic factor
Function: causes allergic reactions by releasing histamine, heparin, leukotriene, and other substances in response to antigenic stimulus

Fat Cell (Adipocyte)

Structure:
- Large, round or polygonal, with flattened ovoid nucleus and thin layer of cytoplasm
- Large lipid droplet
Function: synthesizes and stores fat

Undifferentiated Mesenchymal Cell

Structure: similar to fibrocyte
Function: multidifferentiating potential

Leukocytes (Wandering Cells)

Neutrophils, eosinophils, and lymphocytes
Functions:
- Neutrophils and eosinophils: enter connective tissue, live for a short time, and die
- Lymphocytes: enter tissue, leave through lymphatics, and return to blood circulation
- Increase in number during infections, inflammation, and other pathologic conditions involved in defense

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Description

This quiz covers the general features and functions of connective tissue, including its composition, development, and roles in the body.