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

Marieb - Human Anatomy & Physiology 7th Edition

Marieb, Hoehn7th EditionHuman Anatomy & PhysiologyISBN: 9780805359091Not the one you use?Change textbook

Marieb, Hoehn 7th Edition

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

Problem 11

Chapter 20, Problem 11

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

Verified step by step guidance

Step 1: Understand the role of each cell type listed in the options. Eosinophils are primarily involved in combating parasitic infections and allergic reactions.

Step 2: Cytotoxic T cells (also called CD8+ T cells) are responsible for killing virus-infected cells but are not the primary target of HIV infection.

Step 3: Natural killer (NK) cells are part of the innate immune system and help destroy infected or cancerous cells, but they are not the main cells infected by HIV.

Step 4: Helper T cells (also called CD4+ T cells) play a central role in coordinating the immune response and are the primary cells that HIV targets and invades because the virus binds to the CD4 receptor on their surface.

Step 5: B cells produce antibodies but are not the main target of HIV infection. Therefore, the correct answer is the cell type that HIV most often invades, which is the Helper T cell.

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Key Concepts

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

HIV Target Cells

HIV primarily infects cells that express the CD4 receptor, which the virus uses to enter the cell. The main target is the helper T cell (CD4+ T cell), a crucial immune cell that coordinates immune responses. Understanding which cells HIV invades helps explain the immune system's weakening during infection.

Helper T Cells (CD4+ T Cells)

Helper T cells are a subset of lymphocytes that play a central role in activating and directing other immune cells. They express the CD4 receptor, making them susceptible to HIV infection. Their depletion leads to impaired immune function, characteristic of AIDS.

Immune Cell Types and Functions

Different immune cells have distinct roles: eosinophils combat parasites, cytotoxic T cells kill infected cells, natural killer cells provide innate immunity, and B cells produce antibodies. Recognizing these functions helps differentiate which cells HIV targets and why.

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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

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

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

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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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