BIOLOGY 6
IMMUNE SYSTEM CHEAT SHEET
BEAVERS
IMMUNE SYSTEM: Molecular recognition is the name of the game.
BLOOD (all blood cells originate from stem cells in the bone marrow)
1. Vertebrate blood is a connective tissue consisting of cells suspended in a liquid matrix called plasma.
2. Plasma: 55% water, ions, plasma proteins and substances (nutrients, metabolic waste, respiratory
gases, hormones)
3. Cellular elements: 45% WBC, RBC, Platelets (fragments of bone marrow cells, no nuclei, involved in
blood clotting).
2. RED BLOOD CELLS (RBC): erythrocytes – transport of O2 and some CO2.
3. WHITE BLOOD CELLS (WBC, a.k.a. leukocytes): 5 MAJOR TYPES; neutrophils, lymphocytes (B-cells, T-cells),
monocytes, eosinophils and basophils – defense and immunity.
Phagocytic CELLS
4. Dendritic cells: An antigen-presenting cell, located mainly in lymphatic tissue and skin. Presents antigens to
HELPER-T cells initiating a primary immune response.
5. Macrophages: a phagocytic cell present in many tissues or migrating throughout the body that functions in
innate immunity by destroying microbes and in acquired immunity as an antigen presenting cell.
6. Neutrophils: (WBC) The most abundant type of white blood cell. Neutrophils circulate in blood, are attracted by
signals in infected tissue, are phagocytic and tend to self-destruct as they destroy foreign invaders limiting their
life span to a few days. Neutrophils digest PATHOGENS and cell debris.
7. Eosinophils: A white blood cell that is known to destroy parasitic organisms and play a major role in allergic
reactions. They are often found beneath mucosal surfaces, have low phagocytic activity, but discharge
destructive enzymes when encountering parasites such as worms.
CELLS
8. Mast cell: A vertebrate body cell that produces histamine and other molecules that trigger inflammation in
response to infection and in allergic reactions.
9. Hemocytes: immune cells that travel throughout the body in the hemolymph (the insect circulatory fluid).
10. Natural killer cell: a type of WBC that can kill tumor cells and virus-infected cells as part of innate immunity.
These cells circulate through the body and detect the ABNORMAL ARRAY OF SURFACE PROTEINS characteristic
of some virus-infected and cancerous cells.
11. Lymphocytes originate from stem cells in the bone marrow. B cells are lymphocytes that mature in the bone
marrow. T cells are lymphocytes that migrate from the bone marrow to the thymus (an organ above the heart)
and mature there.
PROTEINS
12. Cytokines: Signaling molecule. Any group of small proteins secreted by a number of cell types including
macrophages, neutrophils and helper T-cells that regulate the function of other cells.
13. Interferons are PROTEINS that provide innate defense by INTERFERING WITH VIRAL INFECTIONS. Interferon-α
and interferon-β, secreted by virus infected cells, help nearby cells resist viral infection; interferon-γ secreted by
T-cells, helps activate macrophages.
14. Antimicrobial Peptides: pathogen recognition TRIGGERS THE PRODUCTION and release of a variety of peptides
and proteins that attack pathogens or impede their reproduction.
15. Lysozyme (an enzyme that destroys bacterial cell walls – in mammals found in sweat, tears, and saliva) further
protects the insects INTESTINES.
16. Antibodies: An antibody is a PROTEIN secreted by PLASMA CELLS (differentiated B cells) that binds to a
particular antigen. Antibody is another term for IMMUNOGLOBULIN.
17. Major histocompatibility complex (MHC) molecule: a host protein that functions in antigen presentation.
18. SUBSTANCES:
19. Histamine: Signaling molecule. A substance released by mast cells that causes blood vessels to DILATE and
become MORE PERMEABLE in inflammatory and allergic responses.
20. Antigens: Any substance that elicits a response from a B cell or a T cell.