Friday, April 3, 2009

Notes from 4/2/09

Hey guys, sorry I couldn't get these up yesterday, my computer wouldn't upload the notes. But here are the notes we took in class yesterday:

B-cell receptors bind intact antigens.

T-cell receptors bind antigens that are displayed by antigens-presenting cells (APCs) on their MHCs.

MHCs (Major histocompatability complex molecules) are proteins that are the product of a group of genes.

There are two types of MHCs:

1. Class I MHCs are found on almost all cells of the body, except RBCs

2. Class II MHCs are made by dendritic cells, macrophages and B cells

The specificity of B and T cells is a result of the shuffling and recombination of several gene segments and results in more than 1 million different B cells and 10 million different T cells.

Each B or T cell responds to only one antigen.

A primary immune response occurs when the body is first exposed to an antigen and lymphocyte is activated.

A secondary immune response occurs when the same antigen is encountered at later time. It is faster and of greater magnitude.

Acquired immunity defends agaisnt infection of body cells and fluids.

Acquired immunity has two branches:

1. Humoral immune response involves the activation and clonal selection of effector B cells which produce antibodies that circulate in the blood.

2. Cell-mediated immune response involves the activation and clonal selection of cytotoxic T cells, which identify and destroy infected cells.

Helper T-cells aid both responses. When activated by interaction with the class II MHC molecule of an APC, they secrete cytokines that stimulate and activate botth B cells and cytotoxic T cells. The helper T cell is bound to the class II MHC by a CD4 protein.

Cytotoxic T cells bind to Class I MHC molecules displaying antigenic fragments on the surface of infected body cells. The cytotoxic T cell is bound to the infeced cell's class I MHC by its CD protein. Cytotoxic T-cells destroy infected body cells.

Mammalian immune system sequence of encountering a pathogen:

1. Antigenic determines from pathogen bind to antigen receptors on lymphocytes.

2. Lymphocytes specific to antigentic determinants from pathogen becomes humerous.

3. Lymphocytes secrete antibodies.

4. Pathogen is destroyed.

5. Only memory cells remain.

A simple and hopefully humerous cartoon of the immune system response:

This is a link to a short animation of the Antibody immunity response to Pathogens, there are not words, but it have some good graphics:

And now for some multiple choice questions:

1. In the inflammatory response, which one of these components would not allow the rest to happen if it did not occur?

A) Increased population of phagocytes in the area
B) Leakage of plasma to the affected area
C) Release of histamine
D) Dilation of arterioles
E) Increased permeability of blood vessels

2. Histamine’s main goal is to:

A) Destroy white blood cells.
B) Attract T cells.
C) Dilate blood vessels.
D) Phagocytize pathogens.
E) Decrease blood flow.

3. _________ interacts with the antigen-class II MHC complex presented by macrophages.

A. B cells
B. Bacterial cells
C. Helper T cells
D. Epithelial cells
E. Cytotoxic T cells

4. Clonal selection is the division of ___________ that have been stimulated by binding to an antigen, which results in the production of cloned ____________.

A. helper T cells ... plasma cells
B. B cells ... plasma cells and memory cells
C. T cells ... B cells
D. B cells ... macrophages
E. macrophages ... B cells and T cells


1. c 2. c 3. c 4. b

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