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

Understand the nature of HIV (Human Immunodeficiency Virus): HIV is a virus that targets the immune system, specifically cells that play a role in coordinating immune responses.

Recall the primary function of each cell type listed in the options: a. Eosinophils are involved in allergic reactions and parasitic infections, b. Cytotoxic T cells destroy infected or cancerous cells, c. Natural killer cells are part of the innate immune system and target infected or abnormal cells, d. Helper T cells coordinate immune responses by activating other immune cells, e. B cells produce antibodies.

Identify the specific cell type that HIV targets: HIV binds to the CD4 receptor, which is found on certain immune cells. Helper T cells (also called CD4+ T cells) are the primary cells that express this receptor.

Understand the consequences of HIV targeting Helper T cells: By infecting and destroying these cells, HIV weakens the immune system, making the body more susceptible to infections and diseases.

Conclude that the correct answer is the cell type with the CD4 receptor, which is the Helper T cell (option d).

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Key Concepts

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

HIV and its Target Cells

HIV (Human Immunodeficiency Virus) primarily targets the immune system, specifically the CD4+ T cells, commonly known as Helper T cells. These cells play a crucial role in orchestrating the immune response by activating other immune cells. The virus binds to the CD4 receptor and co-receptors on these cells, leading to their infection and eventual depletion, which compromises the immune system.

Helper T Cells

Helper T cells are a subset of T lymphocytes that are essential for the adaptive immune response. They assist in activating B cells to produce antibodies and stimulate cytotoxic T cells to kill infected cells. The loss of Helper T cells due to HIV infection leads to a weakened immune system, making the body more susceptible to opportunistic infections and diseases.

Immune System Response

The immune system response involves various cells and mechanisms that work together to defend the body against pathogens. This includes the innate immune response, which provides immediate defense, and the adaptive immune response, which is more specific and involves memory cells. Understanding how HIV disrupts this response, particularly by targeting Helper T cells, is crucial for comprehending the implications of HIV infection and the progression to AIDS.

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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

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

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