Immune Cells Cheat Sheet
Lymphatic System
The two plumbing systems of lymph are
o The lymphatic system - not under pressure
o The circulatory system - under pressure
Pathway for lymph
o Collected from tissue in lymphatic vessel
o Passes through lymph nodes
o Transported in lymphatic vessel by muscular contractions and one way valve system
o Returns to blood
o Leaks out of blood vessels into tissue
Primary lymphoid organs
o Development and maturation of immune cells
o Thymus and bone marrow
Secondary lymphoid organs
o Trap antigens so lymphocytes can interact with them
o Lymph nodes, spleen, MALT and GALT
Thymus
The thymus is a flat bi-lobed organ situated above the heart
The lobes are separated into lobules
Each lobe has two compartments
o Outer cortex filled with immature T cells
o Inner medulla containing some thymocytes
Both lobes are criss-crossed with 3D stromal cell network of epithelial cells, dendritic cells
and macrophages
The function of the thymus is development and maturation of T cells with a positive selection
of T cells with TCR which recognises self-MHC molecules
Immature T cells that cannot recognise antigen MHC complexes or react to strongly with self
MHC are eliminated in the thymus
Lymphatic System
The two plumbing systems of lymph are
o The lymphatic system - not under pressure
o The circulatory system - under pressure
Pathway for lymph
o Collected from tissue in lymphatic vessel
o Passes through lymph nodes
o Transported in lymphatic vessel by muscular contractions and one way valve system
o Returns to blood
o Leaks out of blood vessels into tissue
Primary lymphoid organs
o Development and maturation of immune cells
o Thymus and bone marrow
Secondary lymphoid organs
o Trap antigens so lymphocytes can interact with them
o Lymph nodes, spleen, MALT and GALT
Thymus
The thymus is a flat bi-lobed organ situated above the heart
The lobes are separated into lobules
Each lobe has two compartments
o Outer cortex filled with immature T cells
o Inner medulla containing some thymocytes
Both lobes are criss-crossed with 3D stromal cell network of epithelial cells, dendritic cells
and macrophages
The function of the thymus is development and maturation of T cells with a positive selection
of T cells with TCR which recognises self-MHC molecules
Immature T cells that cannot recognise antigen MHC complexes or react to strongly with self
MHC are eliminated in the thymus
