Page 828 - Fundamentals of anatomy physiology

Chapter 22 The Lymphatic System and Immunity 815

Figure 22–6 The Origin and Distribution of Lymphocytes.

Red Bone Marrow Thymus

One group of stem cells remains in the The second group of stem cells
red bone marrow, producing daughter migrates to the thymus, where
cells that mature into NK cells and B cells. subsequent divisions produce
daughter cells that mature into
Multipotent hemopoietic T cells.
stem cell

Migrate to Thymic
thymus hormones

Interleukin-7 Lymphoid stem cells Lymphoid stem cells
Lymphoid stem cells

Production,
selection, and
differentiation

of T cells

NK cells B cells Mature T cells Mature T cells

B cells and NK cells Mature T cells enter the
enter the bloodstream bloodstream and migrate to
and migrate to the lymph nodes, spleen,
peripheral tissues. and other lymphoid tissues.

Peripheral Tissues

22

All three types Immune surveillance Antibody-mediated immunity Cell-mediated immunity
of lymphocytes
circulate NK cells attack foreign When stimulated, B cells One type of mature T cell,
throughout the cells, body cells can differentiate into called cytotoxic T cells,
body in the infected by viruses, plasma cells, which
bloodstream, and cancer cells. produce and secrete plays a role in
establishing They secrete antibodies. These
immunity. chemicals that NK cells antibodies attach B cell cell-mediated Cytotoxic
lyse the plasma to pathogens.This immunity. These T cell
membrane of the starts a chain cells attack and
abnormal cells. reaction that
leads to the destroy foreign
destruction of
the pathogen. cells or body

cells infected by

viruses.

Abnormal Plasma cell Abnormal
cell cell

Cell destroyed Antibodies Cell destroyed