Immune System and Immunology

Question 1

Innate Immunity

Answer 1

Quick, non-specific, providing a generalized protection from most intruding organisms and toxins.

1. The skin as a barrier to organisms and toxins
2. Stomach acid and digestive enzymes to destroy ingested organisms and toxins
3. Phagocytotic cells such as neutrophils and macrophages
4. Chemicals in the blood.

Question 2

Acquired (adaptive) immunity

Answer 2

Develops more slowly and only after the body has experienced the initial attack.

1. B-Cell immunity: humoral or antibody-mediated immunity
2. T-cell immunity: cell-mediated immunity

Question 3

Causative agents of inflammation that are released by the tissues

Answer 3

Histamine, prostaglandins, lymphokines

Question 4

Function of antibodies in the blood

Answer 4

1. Antibodies may mark the antigen for phagocytosis by macrophages and natural killer cells
2. Once bound, the antibodies may begin a cascade of reactions involving blood proteins (complement) that cause the antigen bearing cell to be perforated
3. The antibodies may cause the antigenic substances to agglutinate (stick together) or even precipitate, or, in the case of a toxin, the antibodies may block its chemically active portion
4. Free antibodies may attach their bases to mast cells. When an antibody whose base is bound to a mast cell also binds to an antigen, the mast cell releases histamine and other chemicals.

Question 5

Goal of both the endogenous and exogenous pathways:

Answer 5

To process an antigen from a pathogen or molecule and display that antigen on an MHC molecule on the cell surface

Question 6

Steps in the endogenous and exogenous pathways

Answer 6

1. Antigen uptake: In the case of the endogenous pathway, the pathogen or molecule is already inside the cell. In the case of the exogenous pathway, the antigen is extracellular and must be phagocytosed
2. Antigen processing: The pathogen or molecule must be processed into smaller peptides (antigens). This occurs in the cytosol in the endogenous pathway, and in vesicles in the exogenous pathway
3. Peptide-MHC association: The antigens then associate with the MHC molecules, which have undergone folding in the EHR. In the endogenous pathway, the antigens are transported into the ER. In the exogenous pathway, a vesicle containing MHC Class II fuses with a vesicle containing antigens
4. Cell surface expression: The end result of both pathways is that the antigen-MHC complex is expressed on the cell surface and can interact with the appropriate immune cells.

Question 7

MHC class I endogenous pathway

Answer 7

all nucleated cell: pathogen is already inside the cell

Question 8

MHC class II exogenous pathway

Answer 8

macrophages, dendritic cells, and some B-cells: pathogen must be phagocytosed (“eaten”) by the immune cell to be destroyed by antigens labeled by cell surface markers

Question 9

Humoral immunity involves the action of:

Answer 9

Immunoglobulins

Question 10

Antibodies function by:

Answer 10

attaching to antigens via their variable portions

Question 11

Lymphatic vessels absorb fluid from the interstitial spaces and carry it to the:

Answer 11

Lymphatic ducts, which return it to the circulation

Question 12

Which of the following would not normally be found in a lymph node?
A. B-lymphocytes
B. Proteins discarded by tissue cells
C. Invading bacteria
D. Old erythrocytes

Answer 12

D. Old erythrocytes

Question 13

An organism exposed to a pathogen for the first time will exhibit an innate immune response involving:
A. B-lymphocytes
B. T-lymphocytes
C. granulocytes
D. An organism exposed to a pathogen for the first time must acquire immunity before it can respond

Answer 13

C. granulocytes