To communicate information about the body's surroundings to the brain
To distribute oxygenated blood to all parts of the body
To protect the body from diseases and remove waste products from the cells
Yellow bone marrow
They move lymphocytes into the organs(spleen,Thymus,ect.)
Kill microorganisms and foreign materials taken up by lymphocytes
To filter lymphocytes into the waste products
Here's an interesting quiz for you.