THE IMMUNE SYSTEM (LECTURE 13) Flashcards
What are the two types of immunity that make up our immune system?
Innate immunity and adaptive immunity.
Characterize innate immunity. What elements make up innate immunity? (3)
Non-specific and fast response (physical and chemical barriers and internal defenses)
List 3 internal defenses that make up the innate immunity.
WBCs (phagocytic and non-phagocytic), antimicrobial peptides and inflammatory response.
Characterize adaptive immunity (acquired immunity).
Specific and slower response, humoral and cell-mediated response.
What is the immune system’s first line of defense?
Physical and chemical barriers.
What are the immune system’s physical and chemical barriers?
Skin, mucous membranes, sweat, saliva, tears and mucous.
Provide an example of a mucous membrane.
The lining of digestive, respiratory and genitourinary tract.
How does sweat defend against pathogens?
Sweat contains acids that inhibit bacterial growth.
How do saliva, tears and mucous defend against pathogens?
These wash away pathogens and contain lysozyme to destroy bacterial cell walls.
What is the immune system’s second line of defense?
The inflammatory response.
When does the inflammatory response occur?
When tissue is damaged or microorganisms enter (or both).
Damaged cells or microorganisms release chemicals that: (4)
Increase permeability and blood flow and bring clotting factors and phagocytic cells to the site.
What is the visible result of chemicals released due to damaged cells or microorganisms.
Swelling, redness and heat.
What 3 primary chemicals are released by damaged cells?
(1) Histamines (2) Prostaglandins (3) Cytokines
Describe phagocytic white blood cells.
They ingest invading microbes.
Name 2 phagocytic white blood cells.
(1) Neutrophils and (2) Macrophages.
Are macrophages part of innate or adaptive immunity?
They participate in both.
Name 3 non-phagocytic white blood cells.
Eosinophils, mast cells and natural killer cells (NK).
What do eosinophils do?
These release chemicals to destroy parasites.
What do mast cells do?
They release histamine.
What do natural killer cells do?
They destroy virus-infected cells and cancer cells by causing cell lysis.
Name 2 (types of?) antimicrobial peptides.
Complement and Interferon.
Describe complement antimicrobial peptides.
> 30 serum proteins and are involved in a cascade of steps which lead to cell lysis of a bacterium or an infected cell (by poking holes in membrane).
Describe interferon antimicrobial peptides.
These are secreted by virus infected cells and they prevent cell-cell spread of the virus and inhibits viral reproduction.
What are the 2 branches of adaptive / acquired immunity.
(1) Humoral and (2) Cell mediated immune response.
What are the key players in adaptive immunity? (4)
Antigens, antibodies, lymphocytes and antigen presenting cells.
What are the 2 types of lymphocytes?
B-cells and T-cells.
What are the 2 types of B-cells?
Plasma cells and memory B-cells.
What are the 2 types of T-cells?
T-helper cells and cytotoxic T-cells.
Name 3 cells that can act as antigen presenting cells.
Macrophages, dendritic cells, B-cells.
What are antigens?
These are proteins or polysaccharides that elicit an immune response - pieces of pathogen.
Are all antigens the same in structure? What does this entail?
No, each type of antigen has a unique structure that a specific T-cell or B-cell receptor will bind to.
Where are antigens found? (7)
On the surface of viruses, virus-infected cells, bacteria, fungi, protozoa, pollen or transplanted tissue.
What do lymphocytes do?
They mediate specific immune responses.
Describe B-cells. (3)
They mature in bone marrow, they produce antibodies and they effect the humoral response.
Describe T-cells. (2)
They mature in thymus and effect the cell-mediated response.
Describe plasma cells.
These are effector B-cells that produce antibodies.
Describe memory B-cells. (what do they have / what do they do?)
These have antigen receptors - they recognize antigens through binding.
What are antibodies? What else are they called?
These are Y-shaped proteins that are also called immunoglobulins.
What are antibodies comprised of?
4 polypeptide chains (2 identical light chains and 2 identical heavy chains).
What is each polypeptide chain that makes up an antibody composed of?
Each chain is composed of a variable region and a constant region.
Describe the variable region of an antibody’s polypeptide chain.
It is an amino acid sequence that varies from antibody to antibody. It binds to a specific antigen.
What is the constant region of an antibody’s polypeptide chain involved in?
It is involved in antigen disposal.
Describe cytotoxic T-cells.
These release perforin and granzymes to kill infected cells.
Describe helper T-cells.
These release chemicals to activate other cells.
Clonal selection is a response to…
to the entry of pathogen.
Clonal selection occurs for…
both T-cells and B-cells.
What are the steps of clonal selection? (3)
(1) Antigen enters body and lymphocyte with matching receptor binds to the antigen. (2) Lymphocyte becomes activated. (3) Two clones are produced.