The document summarizes key components of the immune system. It describes the thymus as the primary lymphoid organ where T cells mature. Within the thymus are epithelial cells, thymocytes that become T cells, dendritic cells, and macrophages. The thymus is larger in newborns and smaller in adults. T cells are categorized as cytotoxic, helper, or regulatory. The thymus also produces hormones that boost immune responses. Bone marrow produces blood cells including red blood cells, white blood cells like T and B cells, and platelets. T and B cells are lymphocytes that respond specifically to antigens. B cells mature in bone marrow while T cells mature in the thymus. Natural killer

2. Synopsis
 Introduction
 B cell
 T cell
 NK cell

3. Abbreviation
 Bone marrow (BM)
 B lymphocytes (B cells)
 T lymphocytes (T cells)
 Red blood cells (RBC)
 White blood cells (WBC)
 Natural killer cells (NK cell)

4. Thymus

5. Thymus
 primary lymphoid organ
 bi-lobed gland
 located above the heart
 Within the thymus, thymus cell lymphocytes /
T cells mature

6. Inside the thymus gland
 Epithelial cells:
act as a protective barrier
 Thymocytes:
cells that become mature T lymphocytes
 Dendritic cells:
help protect against toxins
 Macrophages:
"garbage trucks" of the immune system

7. Changes With Age: Thymus
 Galen: 1st to notice
 Thymus:
large in newborn animals
smaller in adults
Greek philosopher-surgeon: Galen
Note

8. Types of T-Cells
• Cytotoxic T-cells:
responsible for directly killing infected cells
• Helper T-cells:
get the B-cells to make antibodies
• Regulatory T-cells:
• function as "police."
• suppress both B & T cells

9. Hormone Production
• Thymopoietin & Thymulin:
T cells get turned into disease fighters
• Thymosin:
boosts the immune system's response
• Thymic humoral factor:
increase the immune system's response to
viruses

10. Bone marrow (BM)

11. Bone marrow (BM)
 spongy tissue
 inside bones
 produces blood cells
 contains immature cells called stem cells
blood cells
Red blood
cells
White
blood cells
Platelet
s

12. blood cells
• Red blood cells (erythrocytes)
carry oxygen to tissues
• Platelets (thrombocytes)
stop bleeding by helping blood clot
• White blood cells (leukocytes)
fight infections

13. T & B cells
 T cells (thymus cells)
 B cells (bone marrow / bursa of fabricius-derived cells)
 T & B cells: major components @ adaptive immune
response
 T cells: involved in cell-mediated immunity
 B cells: responsible for humoral immunity (relating to Ab)
Ab - Antibody
Note

14. B & T cells
 Both B & T cells are lymphocytes
 derived from HSC (multipotent), in the bone marrow
Note
hematopoietic stem cells (HSC)

15. function of B & T cells
 T & B Cells: involved in the acquired / antigen-
specific immune response
 respond specifically to each antigenic epitope
Epitope: part of the Ag (antigen)
Note

16. difference
Characteristics B lymphocytes (B cells) T lymphocytes (T cells)
Site
of
Maturation
B cells both originate
&
mature in the bone marrow.
T cells mature in the thymus
after its origination in the bone
marrow.
Position outside
the lymph node.
inside
the lymph node.

17. difference
Receptors B-cell receptors (BCRs) T-cell receptors (TCRs)
Binds with Extracellular antigens
(Example: bacteria, free viruses)
foreign Ag in association with
self-antigen only such as a virus-
infected cell.
Antigen
Processing
Antigen processing: not necessary. Antigen processing: necessary.
Connection bind directly with the antigens on the
surface of the invading virus /
bacteria.
can only bind to Ag on the
outside of infected cells & not
directly.
Ag: antigen
Note

18. Bursa of Fabricius

19. Bursa of Fabricius
 primary lymphoid organ of birds
 Mammals do not have Bursa of Fabricius

20. Functions of Bursa of Fabricius
 produces B lymphocytes
 Responsible for antibody production & Humoral
immunity
 B cells mature

21. Natural killer cells (NK cell)

22. NK cell
 also known as large granular lymphocytes (LGL)
 type of cytotoxic lymphocyte
 family of innate lymphoid cells (ILC)
 represent 5–20%
 circulating lymphocytes in humans

23. Thank You
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