The document summarizes the major organs of the immune system, including both primary and secondary lymphoid organs. The primary lymphoid organs, bone marrow and thymus, are responsible for the maturation of immune cells. The secondary lymphoid organs, including lymph nodes, spleen, tonsils, skin, and mucosa-associated lymphoid tissue help the immune system detect pathogens and launch adaptive immune responses through antibody production and lymphocyte activation. Each organ plays a specialized role in the generation, activation, or effector functions of lymphocytes and other immune cells.

1. By
Dr. Priti D.Diwan
Assistant Professor
Department of Zoology
J.D.Patil Sangludkar Mahavidyalay
Daryapur
Organs of the Immune System

2. Immunology
Organs of the Immune System

7. Lymphoid System
 Primary lymphoid organs
 Bone marrow
 Thymus
 Secondary lymphoid organs
 Organized
 Lymph nodes
 Spleen
 Tonsils
 Less organized

8. Lymphatic System
 Network of vessels
 Collects fluid from tissues
 Major cell is lymphocyte
 Unidirectional
 Often first place where antigens are
detected

9. Fig: Lymphatic system
.

10. Thymus
 Structure
 Gross
 Bi-lobed
 Lies above heart
 Microscopic
 Capsular
 Lobules with outer cortex and inner medulla

11.  Fig : Internal structure of Thymus

12. Thymus
 Function
 Takes in immature T cells and puts out
mature (immunocompetent) T cells
 Increased diversity of T cells
 T cell selection

13. Thymus
 T cell selection
 Based on MHC/Ag complex recognition
 Recognize MHC/Non self AG complexes
 Recognize MHC/Self Ag complexes
 Do not recognize MHC/Ag complexes
 Athymic condition
 Natural
 Other

14. Bone marrow
 Structure
 Microscopic
 Less well defined than thymus
 Role of stromal cells
 Function
 Hematopoiesis
 B cell maturation
 B cell selection
 Puts out mature, naive B cells

15. Fig: Structure of Bone Marrow

16. .

17. Lymph Nodes
 Structure
 Gross
 Bean-shaped structures
 Drains major segments of lymphatic system

18. Lymph Nodes
 Structure
 Microscopic
 Major cell types
 Lymphocytes
 Macrophages
 Dendritic cells
 Cortex/paracortex/medulla
 Follicles
 Primary
 Secondary

19.  Fig: Microscopic structure of Lymph
node

20. Lymph Nodes
 Function
 1st line of response to antigens
 Secondary follicle (Germinal center) is site of B
cell proliferation, mutation, differentiation
 Specificity is high
 Lympadenopathy
 Lymphodoema

21. Spleen
 Structure
 Gross
 Ovoid organ in upper left quadrant of abdomen
 Microscopic
 Compartmentalized
 Red pulp
 White pulp
 Periarticualr lymphoid sheath
 Site of Ag presentation
 Major cell types
 Lymphocytes
 Macrophages
 Dendritic cells
 RBCs

23. Spleen
 Function
 Filters out older blood cells
 Responds to Ag in circulatory system
 Produces activated B cells
 Production of blood cells
 Reservior function
 Splenagamy
 Splenotomy

24. Tonsils
 Collection of lymphoid tissue facing into
the aerodigestive track
 1st line of defence against indested or
inhaled foreign pathogens
 Germinal centers appear in response
to Ag
 Produce T lymphocyte in a different
way from spleen’s
 Protective role in URI (Tonsillitis)

25. Fig: Tonsil’s Location

26. Appendix and Peyer’s Patches
 Associated with large intestines and
illium
 Responds to Ag
 Role in GI immune response

27. MALT (Mucosal associated lymphoid
tissue)
 GALT (gut associated lymphoid tissue)
 BALT (bronchial assiciated lymphoid
tissue)
 NALT (nose associated lymphoid
tissue)
 VALT (vulvoveginal lymphoid tissue)

28. Fig: Lymph Tissues

29. References:
 www.innerbody.com
 www.sciencenetlink.com
 www.livestrong.com
 http://www.nature.com/cmi/journal/v
9/n1/pdf/cmi201147a.pdf
 http://www.bio.tamu.edu/courses/mi
crobio/notes/Organs%20of%20the%
20Immune%20System.pdf
 And many more….