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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
All textbooksMarieb, Hoehn 11th EditionCh. 21 The Immune System: Innate and Adaptive Body DefensesProblem 4
Chapter 21, Problem 4

Which antibody class is abundant in body secretions?
a. IgA
b. IgD
c. IgE
d. IgG
e. IgM

Verified step by step guidance
1
Understand that antibodies, or immunoglobulins, are proteins produced by B cells that help the immune system identify and neutralize pathogens.
Recall the five main classes of antibodies: IgA, IgD, IgE, IgG, and IgM, each with distinct roles and locations in the body.
Focus on the function and location of IgA, which is primarily found in mucous membranes and body secretions such as saliva, tears, and breast milk.
Compare IgA with other antibody classes: IgD is mainly a receptor on B cells, IgE is involved in allergic responses, IgG is the most abundant in blood and extracellular fluid, and IgM is the first antibody produced in an immune response.
Conclude that the antibody class abundant in body secretions is IgA, due to its role in mucosal immunity and presence in secretions.

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Key Concepts

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

Antibody Classes

Antibodies, or immunoglobulins, are proteins produced by B cells that recognize specific antigens. There are five main classes: IgA, IgD, IgE, IgG, and IgM, each with distinct roles in immune defense and distribution in the body.
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Classes of Antibodies

IgA and Its Role in Secretions

IgA is the primary antibody found in mucosal areas such as saliva, tears, and mucus. It plays a crucial role in protecting body surfaces exposed to external environments by neutralizing pathogens and preventing their entry.
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IgA

Functions of Other Antibody Classes

IgG is the most abundant in blood and provides long-term immunity; IgM is the first antibody produced during infection; IgE is involved in allergic responses; IgD functions mainly as a receptor on B cells. Understanding these helps differentiate their roles from IgA.
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Classes of Antibodies
Related Practice
Textbook Question

Antibodies released by plasma cells are involved in:

a. Humoral immunity

b. Immediate hypersensitivity reactions

c. Autoimmune disorders

d. All of the above

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Textbook Question

The process by which neutrophils squeeze through capillary walls in response to inflammatory signals is called:

a. Diapedesis

b. Chemotaxis

c. Margination

d. Opsonization

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Textbook Question

Small molecules that must combine with large proteins to become immunogenic are called:

a. Complete antigens

b. Kinins

c. Antigenic determinants

d. Haptens

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Textbook Question

Lymphocytes that develop immunocompetence in the bone marrow are:

a. T lymphocytes

b. B lymphocytes

c. NK cells

d. B and T lymphocytes

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Textbook Question

Cells that can directly attack target cells include all of the following except:

a. Macrophages

b. Cytotoxic T cells

c. Helper T cells

d. Natural killer cells

Textbook Question

All of the following are considered innate body defenses except:

a. Complement

b. Phagocytosis

c. Antibodies

d. Lysozyme

e. Inflammation

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