Macrophages Function and Characteristics

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Questions and Answers

What is the primary function of macrophages in the immune system?

To produce enzymes for protein digestion

To proliferate locally and produce more macrophages

To present antigens to other cells and participate in partial digestion (correct)

To store chemical mediators of inflammatory response

What is unique about the cytoplasm of mast cells?

It is filled with lysosomes

It has a large amount of mitochondria

It is filled with basophilic secretary granules (correct)

It contains a large nucleus

What is the main difference between connective tissue mast cells and mucosal mast cells?

One is a type of macrophage and the other is not

One is involved in the inflammatory response and the other is not

One produces heparin and the other produces chondroitin sulfate (correct)

One is found in skin and the other is found in lungs

What is produced by macrophages?

An array of substances including enzymes and cytokines Signup and view all the answers

What is the role of histamine in the body?

It is a chemical mediator of the inflammatory response Signup and view all the answers

What is the term for the system composed of macrophages?

Mononuclear phagocyte system Signup and view all the answers

What percentage of the human body's dry weight is represented by collagen?

30% Signup and view all the answers

Which type of collagen is characterized as thin and weak, often found in skin, muscle, and blood vessels?

Type III Signup and view all the answers

What is the main function of collagen type I?

Resistance to tension Signup and view all the answers

Which type of collagen is often found together with type I in fetal tissues, skin, bone, and placenta?

Type IV Signup and view all the answers

What is the primary component of elastic fibers?

Elastin Signup and view all the answers

What is the main component of reticular fibers?

Collagen type III Signup and view all the answers

In which stage of elastic fiber development does elastin occupy the center of the fiber bundles?

Third stage Signup and view all the answers

What is the characteristic of elastic fibers that allows them to resume their original shape?

Their ability to snap back to their original length when relaxed Signup and view all the answers

Where can oxytalan fibers be found?

In the zonule fibers of the eye Signup and view all the answers

What is the function of fibroblasts in relation to elastic fibers?

They produce elastin Signup and view all the answers

Study Notes

Macrophages

Characterized by phagocytic ability, macrophages are mature forms of monocytes.
Macrophages can proliferate locally, producing more cells.
Distributed throughout the body, macrophages are present in most organs and constitute the mononuclear phagocyte system.
Act as defense elements and antigen-presenting cells, participating in partial digestion and presentation of antigen to other cells.
Secretary cells that produce an array of substances, including enzymes (e.g., collagenase) and cytokines.

Mast Cells

Oval to round cells with cytoplasm filled with basophilic secretary granules.
Principal function is to store chemical mediators of the inflammatory response.
Secretary granules contain preformed mediators, including:
- Histamine
- Heparin
- Highly acidic, sulfated glycosaminoglycan
Two populations of mast cells:

Connective Tissue Mast Cells
- Found in skin and peritoneal cavity.
- Granules contain the anticoagulant heparin.
Mucosal Mast Cells
- Present in intestinal mucosa and lung.
- Granules contain chondroitin sulfate instead of heparin.

Connective Tissue Fibers

Formed by proteins that polymerize into elongated structures
Three types: collagen, reticular, and elastic fibers

Collagen Fibers

Most abundant protein in the human body (30% of dry weight)
Synthesized by various cell types, not just fibroblasts, chondroblasts, and odontoblasts
Composed of amino acids glycine, proline, and hydroxyproline
Five types:
- Type I: thick, found in dermis, tendon, bone, and dentin; resists tension
- Type II: loose aggregates of fibrils, found in cartilage; resists pressure
- Type III: thin, weak, found in skin, muscle, and blood vessels; often with type I
- Type IV: frequently forms fibers with type I; found in fetal tissues, skin, bone, and placenta; participates in type I function
- Type VI: small fibers found in cartilage; participates in type II function; also found in basal lamina

Reticular Fibers

Consist mainly of collagen type III
Extremely thin, form extensive networks in certain organs
Stain black with silver salts (argyrophilic)
Found in smooth muscle, endoneurium, and hematopoietic organs

Elastic Fibers

Composed of 3 types: oxytalan, elaunin, and elastic fibers
Develop through 3 stages
Can stretch up to 1.5 times their length and snap back to original length
Produced by fibroblasts and smooth muscle cells in arteries
Include:
- Oxytalan: bundle of microfibrils composed of various glycoproteins; found in zonule fibers of the eye
- Elaunin: irregular deposition of elastin between oxytalan microfibrils; found around sweat glands and in dermis
- Elastic fibers: gradual accumulation of elastin until it occupies the center of fiber bundles

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Description

This quiz covers the definition, characteristics, and functions of macrophages, including their phagocytic ability, proliferation, and role in the immune system.