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Biology, Module 4 OCR > Communicable diseases, Disease prevention and The immune system > Flashcards

Communicable diseases, Disease prevention and The immune system Flashcards

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1
Q

Active immunity (4)

A

Stimulates the immune system by producing antibodies specific to antigens presented into the body.

Memory cells are also made so that the immune system recognises the pathogen upon second entry.

Can either be acquired naturally:
Introduction of an antigen from the natural environment.

Or artificially:
Introduction of an antigen through a vaccination.

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2
Q

Organism that causes tuberculosis and the organisms it infects (2)

A
  • Bacteria; mycobacterium tuberculosis

- Animals

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3
Q

How is TB transmitted (2)

A
  • Direct method

- Water droplets through; sneezes, talking

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4
Q

Conditions that increase the change of TB transmission (3)

A
  • Overcrowdness
  • Poor sanitation
  • Weak immune response
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5
Q

Bacteria; include examples (5)

A
  • Prokaryotes
  • Contains cell wall
  • shapes; bacilli, cocci
  • MRSA, E.Coli, TB, Meningitis, ring rot
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6
Q

Viruses(3)

3 examples

A
  • Non living
  • Genetic material surrounded by protein
  • Invades living cells and takes over their bio-chemistry
  • HIV, Influenza, Tobacco mosaic
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7
Q

Fungi(2)

3 examples

A
  • Eukaryotes
  • Saprophytes that mainly affect plants
  • Athletes’ foot, Ring worm, Black Sigatoka
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8
Q

Protista(4)

2 examples in

A
  • Eukaryotes
  • pathogenic ones are parasitic
  • Can uses vectors to get into hosts
  • transmitted through polluted water
  • Malaria, potato blight
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9
Q

Malaria (3)

A
  • Caused by plasmodium Protista
  • transmitted via anopheles mosquito vector
  • infects blood by biting into host
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10
Q

Meningitis (3)

A
  • Caused by bacteria
  • infects the brain
  • causes septicaemia
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11
Q

HIV

A
  • Causes by the human immunodeficiency virus that targets T helper white blood cells.
  • virus contains enzyme, reverse transcriptase that transcribes RNA to DNA and vice versa.
  • spreads through major body fluids; unprotected sex, shared needles(blood), breast milk/ childbirth
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12
Q

Explain how a phagocytes gets rid of bacteria (6)

A
  • Phagocytes recognise the antigen on the bacteria
  • Phagocyte receptor binds on antigen
  • Phagocytosis/ endocytosis occurs and the phagocyte engulfs the bacteria
  • The bacteria is enclosed in a phagosome
  • lysin is releases and breaks down bacteria
  • waste material absorbed by cytoplasm
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13
Q

Immunity (2)

A
  • The ability to be resistant to injury/ infection by foreign proteins, poisons and parasitises
  • Due to the presence of antibodies
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14
Q

Antigen (3)

A
  • Protein that is available on the surface of every microorganism
  • Molecule is complementary and specific to certain antibodies
  • Activates active immunity when introduced to the blood/ tissue
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15
Q

Antibodies (3)

A
  • Produced by plasma white blood cells
  • Specific to foreign antibodies
  • Binds to the antigen to inhibit, destroy or neutralise
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16
Q

Phagocytes (2)

A
  • Type of wbc eg Neutrophils which carry out phagocytosis

- Are attracted to site of infection by chemotaxis and engulf any microbial material

17
Q

Types of T lymphocytes (3)

A
  • T Killer; attach to and destroy invading cells. Secretes interferon which inhibit viral replication. Releases perforin to attack pathogens
  • Memory; remembers antigen and stay in the blood and provides immunological memory.
    Allows pathogen to be recognised if they make a second appearance.
  • Helper; induces and amplifies production of antibodies. Releases interleukins and cytokines that stimulates the production of B lymphocytes and macrophages.
18
Q

Types of B lymphocytes (2)

A
  • Plasma; produces and secretes antibodies
  • memory; remembers antigen and multiply rapidly of there is a future infection
  • effector;divide to form plasma clones
19
Q

Non- specific defences in animals (5)

A
  • Inflammation; mast cells release histamines and cytokines which attract phagocytes
  • Blood clotting: seals wounds using platelets which adhere collagen using thrombosplastin and serotonin
  • Skin; acts as barrier. Sebum inhibits the growth of pathogen
  • lysozyme in tears and urine
  • reflexs; coughing and sneezing, committing and diarrhoea
20
Q

How do fevers fight pathogens (3)

A
  • Cytokines stimulates hypothalamus to rest temperature above 37
  • inhibits reproduction of pathogen
  • helps immune system work faster
21
Q

Opsonins

A
  • Chemicals that bind to pathogens and tag then so that they can be recognised by pathogens
  • Contain sites on phagocytes that allows engulfing of pathogens
22
Q

Cell mediated response

A

Mainly involves T lymphocytes:

  1. Macrophages digest pathogen and presents their antigens bound to a MHC marker, thus becoming an antigen presenting cell (APC).
  2. T- helper cell recognise antigen-MHC complex and binds to it. This activates it to initiate the release of interleukins.

3- Interleukins stimulate the proliferation of T cells: causes production of more memory cells and T killer cells.

23
Q

Describe the shape of antibodies (6)

A
  • Y shaped glycoproteins called immunoglobulins
  • two identical heavy chains held by disulphide bridges
  • light chains outside also bonded to heavy chains
  • Antigen binding site has 110 amino acids and works through ‘lock and key’
  • Variable region; shaped differently in every antibody
  • The rest of the molecule is the same in all antibodies; constant region
24
Q

Parasite

A
  • Organism that gains nutrition/ energy from host
25
Q

Describe the main roles of antibodies. (4)

A

Act as Opsonins:
Binds to antigens and attract phagocytes to eliminate.

Disables pathogens:
Antibodies bind to antigen to form a antigen-antibody complex. This prevents further action of the antigen.

Agglutination:
Antibodies bind with antigen and causes them to clump together. This prevents further movement of antigens and allows localised target of the pathogen.

Anti-toxin:
Binds to toxins released by pathogens, this disabling them.

26
Q

Humoral response in the immune system

A

Mainly involves B cells’ encounter with ‘humours’- free antigen in the blood.

B cells recognise an antigen and uses its receptor to bind to it.

Clonal selection:
T helper cells encounters B cells with antigen binds to it.

Clonal expansion:
T helper cells induces the release of cytokines which initiate B cell proliferation.
The clone cells can differentiate into a plasma or memory lymphocyte.

27
Q

Passive immunity

A

No memory cells are produced. The body’s own immune system does not fight the pathogen.

It is either naturally acquired:
E.g from a mother via the placenta or breast milk- antibodies are transferred

Or artificially acquired:
E.g through an injection of antibodies.

28
Q

What is the general response from plants when an attack from a pathogen occurs? (6)

A

Receptors on the cell membrane recognise molecules that are released via the breakdown of the cell wall.

Other receptors directly recognise the antigens from the pathogen.

This triggers signalling molecules to be sent to the nucleus and switch on genes, so that certain molecules are transcribed.

Polysaccharides like callose and lignin and increased to strengthen the cell wall, preventing further entry of pathogens.

Defensive chemicals are sent out to other plants to warn them of pathogens

Defense molecules are made to attack the pathogen itself.

29
Q

How does inflammation act as a defence against pathogens? (4)

A

Mast cells are activated when a tissue is damaged, this causes the release of histamines and cytokines.

Histamines: cause blood vessels to dilate which causes localised heat and redness. This temperature increase helps to kill pathogens.
Also cause blood vessels to be leaky, which releases more tissue fluid that contains wbc. This causes oedema and pain.

Cytokines: Released with tissue fluid, which attract phagocytes to the site of infection. Phagocytes engulf pathogen.

30
Q

Explain the mechanism of blood clotting, in helping to prevent pathogen infection.

A

At the site of damage, platelets accumulate and adhere when in contact with collagen in the skin.

This triggers the release of thromboplastin, an enzyme that essentially leads to the formation of fibrin, which forms a clot.

Clot acts a physical barrier, preventing further entry of pathogen which epidermis reforms and vessels heal.

Serotonin is also released to contract blood vessels, thus reducing blood flow to damaged area.

31
Q

Ring rot

A

Bacterial disease in plants.

Caused by bacteria- Clavibacter michiganensis

Symptoms include:
Damage to the leaves, tubers and fruit in a plant.

Biology, Module 4 OCR (3 decks)

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