Which parts of the body responsible for immunity?

Organs and Cells of the Immune System

Organs are: Bone Marrow,Thymus, Spleen, Lymph Nodes

Cells are: 

T-Cells: There are two subsets of T-cells: CD4 cells and CD8 cells. CD4 cells secrete factors that activate other white blood cells that participate in the immune response. HIV attacks CD4 cells, damaging the body's ability to initiate the immune response. CD8 cells are important in directly killing tumor cells, viral infected cells and some parasites.





Questions:

1. What do you know about Bone Marrow?
2. What is the responsibility of spleen?

References:

Retrieved on 21/5/2012 from:http://aids.about.com/od/drugfactsheets/a/immuneseries.htm

Define Immune System?

Immune System

define immune system