Ch. 21 The Immune System: Innate and Adaptive Body Defenses

Marieb - Human Anatomy & Physiology 11th Edition

Marieb, Hoehn11th EditionHuman Anatomy & PhysiologyISBN: 9780136874034Not the one you use?Change textbook

Marieb, Hoehn 11th Edition

Ch. 21 The Immune System: Innate and Adaptive Body Defenses

Problem 12

Chapter 21, Problem 12

Name the five antibody classes and describe where each is most likely to be found in the body.

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Identify the five main classes of antibodies (immunoglobulins), which are IgG, IgA, IgM, IgE, and IgD.

Describe IgG as the most abundant antibody in the blood and extracellular fluid, providing long-term immunity and capable of crossing the placenta to protect the fetus.

Explain that IgA is primarily found in mucosal areas such as the respiratory and gastrointestinal tracts, as well as in secretions like saliva, tears, and breast milk, where it protects mucous membranes.

Note that IgM is mainly found in the blood and lymphatic fluid and is the first antibody produced during an initial immune response.

Describe IgE as being associated with allergic reactions and parasitic infections, found bound to mast cells and basophils in tissues.

Mention that IgD is mostly found on the surface of immature B cells in lymphoid tissues and plays a role in initiating B cell activation.

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Key Concepts

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

Antibody Classes (Immunoglobulin Types)

Antibodies, or immunoglobulins, are proteins produced by B cells to identify and neutralize pathogens. There are five main classes: IgG, IgA, IgM, IgE, and IgD, each with distinct structures and immune functions.

Distribution of Antibody Classes in the Body

Each antibody class is predominantly found in specific body locations. For example, IgG circulates in blood and extracellular fluid, IgA is abundant in mucosal areas like saliva and respiratory tract, IgM is mainly in blood plasma, IgE is associated with allergic responses in tissues, and IgD is mostly on B cell surfaces.

Functional Roles of Antibody Classes

Different antibody classes serve unique immune roles: IgG provides long-term immunity, IgA protects mucosal surfaces, IgM is the first responder during infections, IgE mediates allergic reactions and defense against parasites, and IgD functions mainly as a receptor on immature B cells.

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Classes of Antibodies

Related Practice

Textbook Question

Using the letters from column B, match the cell description in column A.

(Note that all require more than a single choice.)

Column A

_____ (1) Phagocytic “cleanup crew”

_____ (2) Releases histamine

_____ (3) Releases perforins

_____ (4) Lymphocyte

_____ (5) Effector cells of adaptive immunity

_____ (6) Antigen-presenting cell

Column B

a. Natural killer cell

b. Neutrophil

c. Dendritic cell

d. Mast cell

e. Cytotoxic T cell

f. B cell

g. Macrophage

h. Helper T cell

i. Basophil

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Textbook Question

The cell type most often invaded by HIV is a(n):

a. Eosinophil

b. Cytotoxic T cell

c. Natural killer cell

d. Helper T cell

e. B cell

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Textbook Question

Besides acting as mechanical barriers, the skin epidermis and mucosae of the body have other attributes that contribute to their protective roles. Cite the common body locations and the importance of mucus, lysozyme, keratin, acid pH, and cilia.

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Textbook Question

Interferons are referred to as antiviral proteins. What stimulates their production, and how do they protect uninfected cells? Which cells of the body secrete interferons?

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Textbook Question

What is complement? How does it cause bacterial lysis? What are some of the other roles of complement?

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Textbook Question

Complement activation promotes all of the following except:

a. Cell lysis

b. Inflammation

c. Opsonization

d. Interferon release

e. Chemotaxis of neutrophils and other cell

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