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10 Cards in this Set

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The antigen dependent phase of B-lymphocyte development occurs in the:

A. Lymph nodes

B. Bone marrow

C. Spleen

D. Blood

E. All of the above



D. Blood
The correct answer is B.

We have discussed at length that B-cells learn their antigen specficity in the bone marrow and T-cells learn their antigen specificity in the thymus.
T- lymphocytes interact with APCs in the :

A. Lymph nodes

B. Thymus

C. Bone Marrow

D. A & B

E. A & C
The correct answer is D.

APCs will present antigen to T-cells in either the lymph nodes of the thymus. However, the thymus becomes less important as the human ages. Why???
(True or False): A TCR can be both soluble and membrane bound.
The correct answer is FALSE. The TCR is always membrane bound and is never found in a secretory form in plasma.
If you wanted an adaptive immune response to lead to neutralization of the virus and eventual phagocytosis, (but not destruction of virus-infected cells) which three of the following types of cells would have to be involved in some part of that complete response (that eventually leads to degradation of the virus)?

A. B- cells

B. TH cells

C. Tc-cells

D. Macrophages
The correct choices are A, C, and D.

You need antibody production by the B-cells for virus neutralization and subsequent phagocytosis (involving macrophages) to destroy those neutralized virusus. Antibody production is facilitated by cytokines released by the TH cells. Since neutralization is occurring in this question, not destruction of the virus-infected cell, Tc cells would not be a correct choice.
(True or False): All TH cells need peptides presented by MHC II.
The correct answer is TRUE.

Helper T-cells bind to antigen presented on an MHC II protein
Which two of the following choices are important differences between innate immune responses and adaptive immune responses?

A. An adaptive response improves significantly with repeated exposures to the same non-self antigen.

B. Each cell involved in innate responses i.e. phagocytes, can be stimulated to respond by many different molecules, which each cell involved in adaptive responses i.e. lymphocytes, can be stimulated to respond by only once molecular structure called an antigen.

C. Innate responses i.e. phagocytosis and complement activation improve significantly with each exposure to antigen.

D. Innate responses often can take 1-2 weeks to begin destroying infectious microorganisms, while adaptive responses destroy infections almost immediately after the very first encounter with a pathogen
The correct choices are A and B.

Innate responses do NOT improve at all, regardless of how many times this type of response takes place. Since phagocytes and complement proteins are always present and ready to respond, the innate response is almost immediate and, thus, does not take 1-2 weeks to become effective. Adaptive immune response does improve because of "memory". Look in your notes and book at the primary response and the quicker and greater secondary response to antigen. Each lymphocyte is specific for only one antigen. Phagocytes, on the other hand, can be stimulated to respond by many different common lipopolysaccharides found on antigen i.e. phagocytes are promiscuous.
The source of all undifferentiated stem cells that can produce any of the cells involved in innate or adaptive immune responses is which of the following?

A. Spleen

B. Bone marrow

C. Liver

D. Thoracic duct

E. any lymph node
The correct answer is B.

All stem cells are made in bone marrow. The spleen and lymph nodes house fully differentiated cells and NOT the undifferentiated stem cells. The thoracic duct is a transporter of cells and NOT a source of cells.
Which of the following cell types is not capable of phagocytosis?

A. dendritic cell

B. macrophage

C. neutrophil

D. TH- cell
The correct answer is D.

Dendritic cells, macrophage and neutrophils play a role in the innate immune response. TH cells can onoy recognize antigen that has already been degraded i.e. processed and presented on an MHC II protein.
Circulating lymphocytes will be found in which one of the following locations just before they enter the blood circulation from the lymphatic system?

A. an endothelial venule

B. bone marrow

C. lymph node

D. thoracic duct

E. spleen
The correct answer is D.

All lymphocytes in the lympatic system eventually enter the last and largest vessel of that system, the thoracic duct. The lymphocytes move from the thoracici duct directly into the vein and subsequently into the blood circulation. Lymphocytes move from the blood into the lymphatic system in the lymph nodes, passing through the systems endothelial venules that pass through each lymph node.
Which of the following interactions between surface molecules must take place for a Tc- cell to be stimulated to begin to destroy a virus-infected cell?

A. MHC I on virus infected cell and CD4 on Tc-cell

B. MHC I on Tc-cell and CD8 on virus infected cell.

C. MHC II on virus infected cell and CD4 on Tc-cell.

D. MHC I on virus infected cell and CD8 on Tc-cell.

E. None of the above choices are correct.
The correct answer is D.

The CD/MHC relationship is critically important in selecting which of the two major T-lymphocyte mediated functions is needed i.e. either help or virus-infected cell destruction. Tc cells have CD8 on their surfaces; CD4 are found on TH cell surfaces and NOT on Tc cells. CD8 can be signaled only if the peptide for which the lymphocyte is specific is being presented by MHC I. MHC II present to TH cells which use CD4 to recognize Class II presentation.