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Unit 4 – The Natural Environment and Species Survival
IMMUNE RESPONSE:
What are the two types of response?
-Non-specific
-Specific
What happens during specific response and what is its speed?
-B cells produce antibodies
-T cells
-Delayed speed
What happens during non-specific response and what is its speed?
-Antimicrobial proteins
-Phagocytosis
-Inflammation
-Immediate

INFLAMMATION:
What is a lysozyme?
-It is an enzyme that is present in tears, saliva and nasal secretions
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What does inflammation at the site of a cut do?
-It helps to destroy invading microbes
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What do histamines do?
-They cause the arterioles in the area to dilate which increases blood flow in the capillaries
at the infected site
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What does this leakage provide?
-It allows plasma fluid, white blood cells and antibodies to leak from the blood into the
tissue causing an oedema (swelling)
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What are phagocytes?
-They are white blood cells that engulf bacteria and other foreign matter in the blood and
tissues
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-Lysosomes fuse with vacuole releasing enzymes that destroy foreign material
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-It passes through the lymph nodes and as lymph passes through the lymph nodes any
pathogens present activate lymphocytes and macrophages, which can then destroy the
microbes
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What is Interferon and what does it do?
-It is a protein that provides non-specific defence against viruses
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-It diffuses to the surrounding cells where it prevents viruses from multiplying
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TYPES OF LYMPHOCYTES:
What are lymphocytes?
-They are white blood cells that help to defend the body against specific diseases
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What are the two main types of lymphocyte?
-B cells and T cells
What do they both do?
-They both respond to antigens called a specific immune response
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ANTIBODIES:
What are antibodies?
-They are special protein molecules of a class known as immunoglobulin
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-They act as labels, allowing phagocytes to recognise and destroy the cell
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-Antibody binds to the antibody receptor on the macrophage
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-The lysosomes fuse with the vacuole releasing digestive enzymes that destroy the
bacterium
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-T cells each have one specific type of antigen receptor on their surface to bind to an
antigen with the complementary shape
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They also enhance the activity of phagocytes
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g
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How are T cells activated?
-Bacterium with antigens on surface is present
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-The macrophage presents antigens on its surface and becomes an antigen-presenting cell
(APC)
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-The T helper cell is activated and divides
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How long do the T memory cells last for?
-They remain for months or years in the body
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CELL CLONAL SELECTION:
How does cell clonal selection occur?
-Bacterium with antigens on surface is present
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-The B cell becomes and Antigen-Presenting cell (APC)
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-The T helper cell then produces cytokines (proteins) that stimulate the B cell
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-The clone of B effector cells then differentiate into plasma cells
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What are B effector cells?
-They differentiate to produce plasma cells which release antibodies into the blood and
lymph
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What are B memory cells?
-These cells are longer-lived and remain for years in the body, enabling an individual to
respond more quickly to the same antigen in the future
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-The cell presents the antigens and becomes an APC
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-The T killer cell divides to form two clones of active T killer cells and memory T killer cells
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-The active T killer cells bind to infected cells presenting antigens
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-The infected cell dies
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-It involves memory cells and only takes about two to seven days
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-There is a greater production of antibodies and the response lasts longer
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