The immune system Flashcards

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1
Q

What is an antigen?

A

Molecules that generate an immune response when detected by the body. The are normally found on the surface of cells and used by the immune system to identify foreign cells.

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2
Q

What four things do antigens help the immune system to identify?

A

Pathogens
Abnormal body cells
Toxins
Cells from other individuals of the same species

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3
Q

What is a phagocyte?

A

A type of white blood cell that carries put phagocytosis. They are the first cells to respond to an immune system trigger inside the body

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4
Q

Explain the process of phagocytosis

A
  1. Phagocyte recognises the foreign antigen on the pathogen
  2. The cytoplasm of the phagocyte moves round the pathogen and engulfs it
  3. The pathogen is contained in a phagocytic vacuole in the cytoplasm of the phagocyte
  4. A lysosome fuses with phagocytic vacuole. Lysozymes break down pathogen
  5. Phagocyte presents the pathogen’s antigens on its cell surface membrane to activate other immune responses
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5
Q

What are T cells?

A

A white blood cell. They have receptor proteins on their surface which binds to complementary antigens presented to it by phagocytes which activates the T cell

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6
Q

What do helper T cells do?

A

Release chemical signals that activate and stimulate phagocytes and T cells. They also activate B cells

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7
Q

What do cytotoxic T cells do?

A

Kill abnormal and foreign cells

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8
Q

What are B cells?

A

White blood cell that is covered with antibodies. Each B cell has a different shaped antibody on its membrane so binds to different shaped antigens

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9
Q

When do B cells become activated?

A
  1. When the antibody on the surface of a B-cell meets a complementary shaped antigen it binds to it.
  2. This (along with help from helper T cells) activates the B cell (clonal selection).
  3. B cell is now activated to divide by mitosis into plasma cells.
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10
Q

What are plasma cells and what do they do?

A

Identical to B cells (clones)
Secrete loads of antibodies specific to antigens (monoclonal antibodies)
Bind to antigen to form an antigen antibody complex

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11
Q

What are antibodies?

A

Chains of amino acids that have a constant region and a variable region (unique tertiary structure). The specificity of antibodies depends on the variable regions (binding sites). Antibodies have 2 binding sites which means that pathogens become clumped together (agglutination).

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12
Q

Name the 2 types of immune response

A

Cellular
Humoral

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13
Q

What is involved in the cellular immune response?

A

T cells and other immune system cells that they interact with

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14
Q

What is involved in the humoral immune response?

A

B cells, clonal selection and production of monoclonal antibodies from humoral response

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15
Q

Describe the primary immune response

A

Slow response as there aren’t many B cells that make the antibody
Symptoms of disease will show
Eventually body will produce enough antibodies
After being exposed to antigen that T cells and B cells will produce memory cells which stay in the body for a long time
Person is now immune

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16
Q

Describe the secondary immune response

A

Quicker and stronger response
Clonal selection happens quicker
Gets rid of the pathogen before any symptoms show

17
Q

What do memory T cells do?

A

Remember specific antigens

18
Q

What do memory B cells do?

A

Record the specific antibodies needed to bind the antigen