Diseases and immunity Flashcards iGCSE Biology

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[h] Diseases and immunity Flashcards iGCSE CIE Biology

[q] What is Active immunity?

[a] Defence against a pathogen by antibody production in the body is called Active immunity. 

[q] Antibodies and immunity

[a]

• Antigens are chemical substances found on the surface of all cells.
• Lymphocytes produce proteins called antibodies which attack the pathogens

[q] Cells

[a] different types of white blood cell work to prevent pathogens reaching areas of the body they can replicate in

[q] Describe the effects of HIV on the immune system? [3]

[a]

• Weakens the immune system / reduces capacity of body to respond to disease / AW;
• Lymphocytes are, damaged / destroyed / killed / not functional;
• (B / T) lymphocytes / white blood cells, stop making antibodies;
• Any two roles of antibodies or lymphocytes or phagocytes which will not happen or not happen very well;;
  • Antibodies stop, pathogens spreading (in the body)
  • Antibodies cause pathogens to, clump / agglutinate
  • Antibodies kill bacteria
  • Antibodies make it easier for phagocytes to ingest pathogens
  • Antibodies, neutralise toxin(s) / make toxins harmless
  • Phagocytes, ingest / AW, pathogens
  • Lymphocytes kill infected cells

[q] Explain how the immune system responds to an invasion of pathogens?

[a]

1. Pathogen are recognized as foreign;
2. Pathogen will have specific / unique antigen;
3. Lymphocytes and Phagocytes are white blood cells;
   • Lymphocytes, make antibodies;
     • Antibodies are as specific shape / complementary to, antigen;
     • Antibodies bind to, antigen;
     • Lymphocytes form memory cells;
       • Known as active / long-term, immunity;
   • Phagocytes, engulf, pathogens;
     • Phagocytes, have enzymes / digest pathogens;

[q] Explain how vaccination can control the spread of disease?

[a]

1. The vaccine consist of a harmless form of pathogen.
2. The vaccine is then injected into the patient.
3. Pathogen contains specific antigen.
4. This stimulates an immune response to occur. (This is known as active immunity)
   • Lyphocytes produce antibodies which are specific to the antigen.
   • B Lymphocytes form memory cells, which remain in the body for a long time
5. If the patient is exposed to the same pathogen, there will be a rapid / quick immune response.
   • If a large amount of the population are vaccinated, this is known as herd immunity.
6. Harmless / dead, form of, (named) pathogen / antigen used;
7. (Vaccine) injected/swallowed;
8. ref to specific / unique / AW, antigen;
9. Lymphocytes make antibodies;
10. ref to memory cells;
11. ref to active immunity;
12. rapid, immune response / AW, if exposure to same pathogen;
13. herd immunity;
14. AVP; e.g: detail of active immunity / smallpox became extinct.

[q] Explain why it is important to complete a full treatment of antibiotics?

[a]

[q] How do antibodies work?

[a] Process:

[q] How does antibiotics help with disease?

[a]

• (antibiotics) kill / damage/ destroy /eliminate, pathogens /bacteria /fungi; 
• Bacteria /fungi /pathogen can cause illness /disease /infections; 
• (antibiotics),prevent growth /reproduction of, bacteria /fungi / pathogen; 
• AVP ref. to how antibiotics kill bacteria; e.g. ref. to cell wall / production of proteins /inhibition metabolism;

[q] Mechanical barriers

[a] Structures that make it difficult for pathogens to get past them and into the body

[q] Passive immunity

[a]

• Passive immunity is a short-term defense against a pathogen and can be gained through acquiring antibodies from another individual.
• Examples:
  • Natural: Antibodies being passed to a baby through the mother’s milk
  • Artificial: Injected antibodies (serum) for certain diseases where the individual is already infected and a fast response is required
• Memory Cells are NOT produced through Passive Immunity

[q] What is a Pathogen?

[a] A disease-causing organism is called a Pathogen.

[q] Tissue Rejection / Autoimmune Disease

[a]

• Caused by an immune response on healthy body cells, where they are targeted and destroyed by the immune system.

• • How?
    • Recognition tissue is foreign due to unknown antigens;
    • Lymphocytes release antibodies;
    • Phagocytes / lymphocytes cause tissue destruction;

• E.g: Type 1 Diabetes
  • Inability of islet cells in the pancreas to produce sufficient insulin

[q] What is a Transmissible disease?

[a] A disease in which the pathogen can be passed from one host to another is called Transmissible disease.

[q] Types of body defences

[a]

• Mechanical barriers,
  •  Skin 
  •  Hairs in the nose
• – Chemical barriers,
  • Mucus
  • Stomach acid
• – Cells,
  • Phagocytosis
  • Antibody production by white blood cells
• – which can be enhanced by vaccination

[q] Ways to Prevent Transfer of Pathogens

[a]

• Hygienic Food Preparation
• Personal Hygiene
• Waste Disposal
• Sanitation

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