Week 11 - Immune System & Lymphatics

What are the two major components of the immune system?

• immune cells

• lymphoid organs and tissues

What are the primary lymphoid organs/sites?

• bone marrow

• thymus

What is the significance of primary lymphatic organs?

they are sites where stem cells differentiate and mature into B and T lymphocytes

What is the significance of secondary lymphoid organs and tissues?

• they are sites where mature B and T cells migrate (from primary lymphoid organs)

• cells here are sequestered for future use or move to where active immune responses are occurring

What are the secondary lymphoid organs?

• thymus

• spleen

• lymph nodes

What are the secondary lymphoid tissues?

lymphoid nodules

What is significant about the spleen?

reserve for RBCs and immune cells

What are leukocytes?

white blood cells

What are the different types of leukocytes?

• neutrophils

• eosinophils

• basophils

• monocytes

• lymphocytes

What are neutrophils?

• phagocytes which engulf and destroy foreign material

• strongest response takes place in reaction to bacterial infection and tissue trauma

• release histamine to promote local inflammation

Which leukocytes release histamine as part of their immune response?

• neutrophils

• basophils

What are eosinophils?

• weak phagocytes

• destroy foreign material by releasing cytokines

• strongest response to parasites

• contribute to allergic reactions

What are the functions of basophils?

• release histamine to widen blood vessels

• release heparin to prevent unwanted blood clots

• release leukotrienes which act as powerful inflammatory mediators which narrow airways and increase blood vessel leakiness

• release prostaglandins

True or false: unlike true hormones that travel through the blood from distant glands, prostaglandins act right where they are made

true

What are prostaglandins?

fat-based hormone-like chemical messengers made by nearly all cells in the body that regulate local processes like inflammation, blood flow, and muscle contractions

What are monocytes?

What are lymphocytes?

What are mast cells?

What are dendritic cells?

What is the thymus?

What are the lymph nodes?

What is the primary function of lymph nodes?

What are lymphoid nodules?

What are Peyer’s patches?