Basic Components of the Immune System Flashcards
The process by which hematopoietic stem cells (HSCs) differentiate into mature blood cells is called
Hematopoiesis
Primary lymphoid organs
Bone marrow and the Thymus
regulate the development of immune cells from immature precursors
Secondary lymphoid organs:
•Including the spleen, lymph nodes, and specialized sites in the gut and other mucosal tissues
–Coordinate the encounter of antigen with antigen-specific lymphocytes and their development into effector and memory cells.
HSCs are defined by two capacities:
- The ability to regenerate or “self-renew”
- The ability to differentiate into all diverse blood cell types.
One HSC is present per ________ cells in the bone marrow.
5 x 104 (rare)
Myeloid cells and NK cells:
Are memembers of the innate immune system
First cells to respond to infection or other insults
Lymphocytes are:
Members of the adaptive immune response
Generate a refined antigen specific immune response that also gives rise to immune memory
Granulocytes:
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Neutrophils, Basophils, Mast cells, and Eosinophils
- All granulocytes have multilobed nuclei
- The cytoplasm contains granules that are released in response to contact with pathogens
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Monocytes:
- Migrate into tissues in response to infection
- Can differentiate into specific tissue macrophages:
- Osteoclasts in the bone
- Microglial cells in the central nervous system
- Alveolar macrophages in the lung
Myeloid Antigen-Presenting Cells:
- Monocytes, macrophages, and dendritic cells
- Professional antigen-presenting cell (APC)
- Considered cellular bridges between the innate and adaptive immune systems
Cells of the Lymphoid Lineage Regulate:
Adaptive Immune Response
Lymphocytes:
Three major populations:
– Principal cell players in the adaptive immune response.
– 20% to 40% of circulating white blood cells and 99% of cells in the lymph.
- B lymphocytes (B cells), expresses B cell Receptor
- T lymphocytes (T cells), expresses T cell Receptor
- No contact With antigen: naïve
- Contact antigen: lymphocytes proliferate and differentiate into both effector cells and memory cells.
- Natural Killer Cells (NK cells)
B Lymphocyte (B cell): Derived its letter from its site of maturation
Bursa of Fabricius in birds
Bone marrow in mammals
Mature B cells Display ___________
- Display B-cell receptor (BCR)
- Membrane-bound immunoglobulin (antibody) molecule that binds to antigen.
- Can recognize soluble or particulate antigen
- – Activated B cells differentiate into effector cells known as Plasma cells
- lose expression of BCR and become highly specialized for secretion of antibody
T Lymphocytes:
Derive their letter (T) from their site of maturation in the thymus
Expresses a unique antigen-binding receptor called the
T-cell receptor
–Only recognize processed pieces of antigen (typically peptides) bound to cell membrane proteins called major histocompatibility complex (MHC)