Chapter Questions - Immunity

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1

What distinguishes the innate defense system from the adaptive defense system?

What distinguishes the innate defense system from the adaptive defense system?

The innate defenses reduce the workload of the adaptive system by preventing the entry and spread of microorganisms in the body.
innate is nonspecific, adaptive is specific
The innate defense system is always ready to respond immediately, whereas it takes more time to mount the adaptive defense system.

2

What is the first line of defense against disease?

What is the first line of defense against disease?

The innate defense system is the first line of defense against disease. The skin and the mucous membranes are part of the innate defense system. As long as the epidermis is unbroken, a formidable physical barrier is presented to most microorganisms

3

What is opsonization and how does it help phagocytes? Give an example of a molecule that acts as an opsonin.

What is opsonization and how does it help phagocytes? Give an example of a molecule that acts as an opsonin.

Opsonization is the process of making pathogens easier for phagocytes to grab onto and phagocytize by decorating their surface with molecules to which the phagocytes receptors can bind. An example that includes opsonin is the lectin pathway. It is a type of the complement system. Mannan-binding lectin proteins play a major role in activation of this pathway. Opsonin belongs to the same family as C1q, a family called the collectins.

4

Under what circumstances might NK cells kill are our own cells?

Under what circumstances might NK cells kill are our own cells?

Our own cells are killed by NK cells when they have been infected by viruses or are cancerous.

5

What are the four cardinal signs of inflammation and what causes them?

What are the four cardinal signs of inflammation and what causes them?

1. Pain – actions of chemical mediators (kinins and prostaglandins) on the nerve endings, and the swelling which can compress nerve endings.

2. Redness – (hyperemia) vasodilation of arterioles which increase blood flow to the affected area.

3. Heat – (hyperemia) vasodilation of arterioles which increase blood flow to the affected area.

4. Swelling – release of histamine and other chemical mediators of inflammation that increase capillary permeability

6

Name the three characteristics of adaptive immunity.

Name the three characteristics of adaptive immunity.

1. It is specific. It recognizes and is directed against particular pathogens or foreign substances that initiate the immune response.

2. It is systemic. Immunity is not restricted to the initial infection site.

3. It has “memory.” After an initial exposure, it recognizes and mounts even stronger attacks on the previously encountered pathogens.

7

What is the difference between a complement antigen and a hapten?

What is the difference between a complement antigen and a hapten?

A complete antigen has immunogenicity and reactivity, whereas a hapten has reactivity but not immunogenicity.

8

What marks the cell as "self" as opposed to "nonself"?

What marks the cell as "self" as opposed to "nonself"?

Self-antigens, particularly MHC proteins, mark the cell as self. (MHC=Major histocompatibility complex)

9

What event (or observation) signals that a B or T cell has achieved immunocompetence?

What event (or observation) signals that a B or T cell has achieved immunocompetence?

Developement of immunocompetence of a B or T cell is signaled by the appearance on its surface of a specific and unique membrane-bound antibody.

10

Which of the following T-cells would survive education in the thymus?

a) one that recognizes neither MHC nor self-antigen,
b) one that recognizes both MHC and self-antigen
c) one that recognizes self-antigen but not MHC.

Which of the following T-cells would survive education in the thymus?

c) one that recognizes self-antigen but not MHC.

11

Name three different APCs. Which is most important for T lymphocyte activation?

Name three different APCs. Which is most important for T lymphocyte activation?

Dendritic cells, macrophages, and B cells can all act as APCs. DEndritic cells are most important for T cell activation.

12

In clonal selection, "who" does the selecting? What is being selected?

In clonal selection, "who" does the selecting? What is being selected?

In clonal selection, the antigen does the selecting. What is being selected is a perticular clone of B or T cells that has antigen receptors corresponding to that antigen.

13

Why is the secondary response to an antigen so much faster than the primary response?

Why is the secondary response to an antigen so much faster than the primary response?

The secondary response to an antigen is faster than the primary response because the immune system has already been "primed" and has memory cells that are specific for that particular antigen.

14

How do vaccinations protect against common childhood illnesses such as chicken pox, measles, and mumps?

How do vaccinations protect against common childhood illnesses such as chicken pox, measles, and mumps?

Vaccinations protect by providing the initial encounter to and antigen-the primary response to that antigen. As a result, if the pathogen is encountered again, it elicits a much faster, more powerful secondary response.

15

Which class of antibody is most abundant in blood? Which is secreted first in the primary immune response? Which is most abundant in secretions?

Which class of antibody is most abundant in blood? Which is secreted first in the primary immune response? Which is most abundant in secretions?

IgG antibody is most abundant in the blood. IgM is secreted first in a primary immune response. IgA is most abundant in secretion.

16

List four ways in which antibodies can bring about destruction of a pathogen.

List four ways in which antibodies can bring about destruction of a pathogen.

Antibodies can bring bout destruction of pathogen via "PLAN" -Phagocytosis, Lysis (via complement), Agglutination, or Neutralization.

17

Class II MHC proteins display what kind of antigens? What class of T cells recognizes antigens bound to class II MHC? What type of cells display these proteins?

Class II MHC proteins display what kind of antigens? What class of T cells recognizes antigens bound to class II MHC? What type of cells display these proteins?

Class II MHC proteins display exogenous antigens. Class II MHC proteins are recognized by CD4 T cells (usually become helper T cells). APCs display class II MHC proteins.

18

What happens when antigens are bound in the absence of co-stimulators?

What happens when antigens are bound in the absence of co-stimulators?

When antigens are bound in the absence of co-stimulators this causes the lymphocyte to develop anergy -a state of permanent unresponsiveness to that antigen.

19

Which type of T cell is the most important in both cell-mediated and humoral immunity? Why?

Which type of T cell is the most important in both cell-mediated and humoral immunity? Why?

The helper T cells are central to humoral and cellular immunity because they are required for activation of both cytotoxic T cells and most B cells

20

Describe the killing mechanism of cytotoxic T cells that involves perforins.

Describe the killing mechanism of cytotoxic T cells that involves perforins.

The cytotoxic T cell release perforins and granzymes onto the identified target cells. Perforins form a pore in the target cell membrane, and granzymes enter through the pore, activating enzymes that trigger apoptosis

21

Which proteins must be carefully matched before an organ transplant?

Which proteins must be carefully matched before an organ transplant?

MHC proteins and blood type antegens (ABO, etc.) are carefully matched before and organ transplant.

22

What makes HIV particularly hard for the immune system to defeat?

What makes HIV particularly hard for the immune system to defeat?

HIV is particularly for the immune system to defeat because

1. It destroys helper T cells, which are key players in adaptive immunity

2. It is a high mutation rate and so it rapidly becomes resistant to drugs.

23

What event triggers the release of histamine from mast cells in an allergic response?

What event triggers the release of histamine from mast cells in an allergic response?

Binding of an allergen onto specific IgE antibodies attached to mast cells triggers the mast cells to release histamines