Immune System Flashcards

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1
Q

Purpose of the Immune System

A

To protect the body against harm (caused by infection) of small microorganisms called pathogens

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2
Q

Natural barriers against infection

A

Skin: a physical barrier which secretes antimicrobial substances
blood clotting: seals wounds to prevent infection
Phagocytosis: engulfs and digests any foreign bodies in the blood
Inflammation: helps to isolate foreign substances and prevents further contact with the body
Mucus: mucous membranes of the respiratory system release mucus to waft mucus inhaled
Lysozymes: found in tears, saliva and stomach acid which kill bacteria

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3
Q

Phagocytosis

A

-Phagocyte recognises foreign antigens & receptors bind to it
- cytoplasm moves around and engulfs the pathogen (it’s now present as a phagosome)
- A lysosome fuses with the phagosome to form a phagolysosome
- Lysozymes hydrolyse the pathogen in the phagolysosome
- Soluble debris exists the cell via exocytosis
- Phagocyte displays the pathogens antigen on it’s surface

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4
Q

Inflammation

A
  • At a wound, damaged cells release a chemical (histamine)
  • These chemicals caused blood vessels to leak fluid into the tissues leading to swelling
    -This helps to isolate and prevent the pathogen from making further contact with the body
  • They also attract phagocytes (WBC)
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5
Q

Antibody

A

Proteins synthesised by B cells which are specific to 1 antigen, they bind to form an antigen antibody complex

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6
Q

Aggulation

A

-antigens bind to two antigens at a given time forming antigen antibody complexs
-this leads to pathogens clumping up (angulation)
-This makes pathogens easier to find and phagocytosis to take place

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7
Q

Cell mediated immune response (T lymphocytes)

A

Specific (helper) T cells with complementary receptors bind to antigen on antigen presenting cell
This activates the T cells to divide by mitosis, stimulate B cells & phagocytes

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8
Q

Types of T lymphocytes

A
  • Helper T cells: activate B lymphocytes & stimulate phagocytosis
  • Cytotoxic T cells: create pores in plasma membrane of pathogens by producing perforin
  • Memory T cells: remain in blood until another infection, they then divide rapidly by mitosis
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9
Q

Humoral Response (B Lymphocytes)

A
  • B lymphocyte cells are covered in receptors for their specific antigen
  • Once they find the complementary receptor, their stimulated by helper T cells (that release cytokines)
  • They differentiate into plasma or memory b cells
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10
Q

Type of B lymphocytes

A

-Plasma Cells: rapidly produce antibodies which cause antigens to become inactivated
- memory cells: remain in blood circulation (for years) until the same antigen appears, they then rapidly divide by mitosis

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11
Q

Primary vs Secondary exposure

A

The second exposure produces antibodies faster and at a higher rate, as the antigens are detected and memory cells can rapidly undergo mitosis to produce antibodies

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12
Q

Lag time

A

The time at the primary exposure when the correct complementary antibody is being found for the pathogens antigens

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