Ch. 16 - Innate Immunity: Nonspecific Defenses of the Host

Tortora - Microbiology: An Introduction 14th Edition

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Tortora 14th Edition

Ch. 16 - Innate Immunity: Nonspecific Defenses of the Host

Problem 3

Chapter 16, Problem 3

If the following are placed in the order of occurrence, which would be the third step?
a. Diapedesis
b. Digestion
c. Formation of a phagosome
d. Formation of a phagolysosome
e. Margination

Verified step by step guidance

First, understand the sequence of events in the process of phagocytosis, which is how immune cells like neutrophils or macrophages engulf and destroy pathogens.

Identify the initial steps where immune cells move toward the site of infection: margination (e) is when leukocytes move to the blood vessel walls, followed by diapedesis (a), where they squeeze through the vessel walls into the tissue.

Next, the immune cells encounter the pathogen and engulf it, leading to the formation of a phagosome (c), which is a vesicle containing the ingested particle.

After the phagosome forms, it fuses with a lysosome to create a phagolysosome (d), where digestive enzymes break down the pathogen.

Finally, digestion (b) occurs inside the phagolysosome, where the pathogen is degraded by enzymes.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Phagocytosis Process

Phagocytosis is a cellular mechanism where immune cells engulf and destroy pathogens. It involves sequential steps including recognition, attachment, ingestion, and digestion of microbes, essential for innate immunity.

Diapedesis and Margination

Margination is the process where white blood cells move toward the blood vessel walls, followed by diapedesis, where they squeeze through the vessel walls to reach infection sites. These steps precede phagocytosis.

Phagosome and Phagolysosome Formation

After engulfing a pathogen, the immune cell forms a phagosome, a vesicle containing the microbe. This then fuses with a lysosome to form a phagolysosome, where digestive enzymes break down the pathogen.

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Textbook Question

How can the complement system cause endotoxic shock?

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Textbook Question

If the following are placed in the order of occurrence, which would be the third step?

a. Activation of C5 through C9

b. Cell lysis

c. Antigen–antibody reaction

d. Activation of C3

e. Activation of C2 through C4

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Textbook Question

Patients with X-linked chronic granulomatous disease are susceptible to infections because their neutrophils don’t generate an oxidative burst. What is the relation of the oxidative burst to infection?

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Define inflammation, and list its characteristics.

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Textbook Question

What are interferons? Discuss their roles in innate immunity.

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Textbook Question

Chlamydia can prevent the formation of phagolysosomes and therefore can

a. avoid being phagocytized.

b. avoid destruction by complement.

c. prevent adherence.