Component 3A - The Immune Response Flashcards

1
Q

How does your body protect you when the skin barrier is breached?

A
  • Blood clotting to seal wounds
  • Inflammation to localise breaks in the barrier - raised temperature is unfavourable and large amount of blood flow brings lots of phagocytes
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2
Q

How does the skin resist infection and how is it maintained?

A

• The skin is a tough barrier and vitamin C is needed to

maintain collagen in strong connective tissue

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3
Q

How does skin flora resist infection?

A
  • Skin flora offer protection by competing with pathogenic bacteria and unlike these bacteria, the flora is not easily removed by washing
  • This means regular washing is a good way of resisting infection
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4
Q

How does the body resist infection when microbes enter the blood stream or are breathed in?

A

• Phagocytosis to destroy invading microbes
• Ciliated mucous membranes that trap microbes in
inhaled air

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5
Q

What enzyme does the body contain to resist infection?

A

Lysozyme in tears, saliva and stomach acid that kills

bacteria.

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6
Q

Where do b lymphocytes originate and mature

A

Originate from stem cells in the bone marrow, and mature in the
spleen and lymph nosed

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7
Q

What is the humoral response?

A

• Each B lymphocyte has receptors for the detection of its specific antigen
• Activation stimulates the rapid increase of antibody producing cells, plasma cells (produce antibodies), and memory cells
• Memory cells remain in the circulation ready to divide if the same antigen is encountered
again. Turn into plasma cells and release antibodies

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8
Q

Phagocytes role in humoral response

A

• An antigen-antibody complex means the antigen is inactive, for example the microbes can agglutinate which increases the rate of engulfment by phagocytes in humoral response.

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9
Q

Describe the features of antibodies and their interactions with antibodies

A

• Antibodies are proteins (globulins) which are specific to the antigen with which they bind
to form an antigen-antibody complex
• Antibodies are Y- shaped, formed from four polypeptide chains and have two binding
sites

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10
Q

Where do T lymphocytes originate and where are they activated?

A

T lymphocytes, which also originate from stem cells in the bone marrow, but are
activated in the thymus gland

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11
Q

What is the cell-mediated response?

A
  • Detection of the corresponding specific antigen causes the proliferation of T lymphocytes;
  • There are many subpopulations of T cells which T lymphocytes can divide to make
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12
Q

What cells are produced during cell-mediated response and what are their role?

A

1) Effector cells (T killer or cytotoxic T lymphocytes) which cause lysis of the target cells
2) Memory cells which remain dormant until the host is next exposed to the antigens
3) Helper T cells which cooperate with B lymphocytes to initiate an antibody response
4) T cells do this by releasing cytokines which stimulate phagocytic cells, clonal expansion of B and T lymphocytes and cause B lymphocytes to make antibodies

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13
Q

What is the primary immune response?

A

• Following first exposure to a foreign antigen there is a latent period where macrophages carry out phagocytosis and incorporate foreign antigen into their cell membranes - antigen presentation
• T helper cells detect these antigens and secrete cytokines which stimulate B cells and
macrophages
• B cells are activated and undergo clonal expansion – some then differentiate to become
antibody secreting plasma cells with short lives and others to become long lived memory
cells that retain the ability to undergo mitosis

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14
Q

How long does it take for a primary response to work?

A

A low level of antibody is secreted which over a period of 2 – 3 weeks clears the infection
and symptoms disappear.

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15
Q

What is a secondary immune response?

A

• Re-exposure to the same antigen means a very short latent period due to the
presence of memory cells;
• A small amount of antigen is required to stimulate rapid production of plasma cells
• Antibody levels increase 10-100 times greater than the initial response and in a very short time
• Antibody levels stay high for longer and no symptoms develop

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