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The Immune System
What is an immune response?
Is the body's reaction to a foreign antigen.
What are antigens?
Antigens are molecules (usually proteins or polysaccharides) found on the
surface of cells.
Explain the stages of Phagocytosis
A phagocyte recognises the antigens on a pathogen.
They cytoplasm of the phagocyte moves round the pathogen,
engulfing it. This may be made easier by the presence of opsonins.
The pathogen is now contained in a phagosome ( a type of vesicle) in
the cytoplasm of the phagocyte.
A lysosome (an organism that contains digestive enzymes) fuses with
the phagosome. The enzymes break down the pathogen.
The phagocyte then presents the pathogen's antigens. It sticks the
antigens on it's surface to activate other immune system cells. When a
phagocyte does this it is acting as an antigen-presenting cell APC.
What are Opsonins?
Molecules in the blood that attach to foreign antigens to aid
phagocytosis.
What are Neutrophils?
A type of phagocyte.
What do Neutrophils do?
They're the first white blood cells to respond to a pathogen inside the
body. Neutrophils move towards a wound in response to signals from
cytokines. The cytokines are released by cells at the site of the wound.
What are cytokines?
The Immune System 1
The Immune System
What is an immune response?
Is the body's reaction to a foreign antigen.
What are antigens?
Antigens are molecules (usually proteins or polysaccharides) found on the
surface of cells.
Explain the stages of Phagocytosis
A phagocyte recognises the antigens on a pathogen.
They cytoplasm of the phagocyte moves round the pathogen,
engulfing it. This may be made easier by the presence of opsonins.
The pathogen is now contained in a phagosome ( a type of vesicle) in
the cytoplasm of the phagocyte.
A lysosome (an organism that contains digestive enzymes) fuses with
the phagosome. The enzymes break down the pathogen.
The phagocyte then presents the pathogen's antigens. It sticks the
antigens on it's surface to activate other immune system cells. When a
phagocyte does this it is acting as an antigen-presenting cell APC.
What are Opsonins?
Molecules in the blood that attach to foreign antigens to aid
phagocytosis.
What are Neutrophils?
A type of phagocyte.
What do Neutrophils do?
They're the first white blood cells to respond to a pathogen inside the
body. Neutrophils move towards a wound in response to signals from
cytokines. The cytokines are released by cells at the site of the wound.
What are cytokines?
The Immune System 1
