Lymphatic System: Lymphatic Organs
1. Primary lymphoid organs, where B and T cells originate and mature, are the bone marrow and thymus. Fill
in the following:
Both B and T cells originate from the bone marrow.
The B cells mature in the bone marrow.
The T cells mature in the thymus.
(Hint: This is how they came to be called B and T cells.)
2. Secondary lymphoid organs, where lymphocytes become activated, include the following structures:
a. lymph nodes
b. spleen
c. Peyer’s patches
d. appendix
e. tonsils
3. The lymph is filtered through the lymph nodes, where antigens and pathogens are removed and the
immune system can be activated.
4. Name two functions of the lymph nodes:
1. removal of antigens and other debris
2. activation of the immune system (B and T cells)
5. While afferent lymphatic vessels carry lymph from the tissues to the lymph nodes, efferent lymph vessels
carry cleansed lymph away from the lymph nodes.
6. B cells are found in the germinal centers of the lymphoid follicles, and T cells wander through the deep
cortex, searching dendritic cells for their special antigen.
7. The spleen cleanses the blood like the lymph nodes cleanse the lymph.
8. Functions of the spleen include:
Removes pathogens, aged erythrocytes, and platelets
1. Primary lymphoid organs, where B and T cells originate and mature, are the bone marrow and thymus. Fill
in the following:
Both B and T cells originate from the bone marrow.
The B cells mature in the bone marrow.
The T cells mature in the thymus.
(Hint: This is how they came to be called B and T cells.)
2. Secondary lymphoid organs, where lymphocytes become activated, include the following structures:
a. lymph nodes
b. spleen
c. Peyer’s patches
d. appendix
e. tonsils
3. The lymph is filtered through the lymph nodes, where antigens and pathogens are removed and the
immune system can be activated.
4. Name two functions of the lymph nodes:
1. removal of antigens and other debris
2. activation of the immune system (B and T cells)
5. While afferent lymphatic vessels carry lymph from the tissues to the lymph nodes, efferent lymph vessels
carry cleansed lymph away from the lymph nodes.
6. B cells are found in the germinal centers of the lymphoid follicles, and T cells wander through the deep
cortex, searching dendritic cells for their special antigen.
7. The spleen cleanses the blood like the lymph nodes cleanse the lymph.
8. Functions of the spleen include:
Removes pathogens, aged erythrocytes, and platelets
