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Disease and the Immune System Flashcards

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1
Q

What is a disease?

A

A disease is a condition that impairs the normal functioning of an organism. Both plants and animals can get diseases.

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1
Q

What is a pathogen?

A

A pathogen is an organism that causes disease. Types of pathogens include bacteria, viruses, fungi, and protoctista.

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2
Q

What is a communicable disease?

A

A communicable disease is a disease that can spread between organisms.

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3
Q

What type of pathogen/disease is tuberculosis and what does it affect?

A

It is a bacterial pathogen and it affects animals- typically cattle and humans

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4
Q

What type of pathogen/disease is Meningitis and what does it affect?

A

It is a bacterial pathogen and it affects humans

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5
Q

What type of pathogen/disease is HIV/AIDS and what does it affect?

A

It is a viral pathogen and it affects humans

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6
Q

What type of pathogen/disease is Ring rot and what does it affect?

A

It is a bacterial pathogen and it affects potatoes and tomatoes

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7
Q

What type of pathogen/disease is Influenza and what does it affect?

A

It is a viral pathogen and it affects animals- including humans

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8
Q

What type of pathogen/disease is Tobacco mosaic virus and what does it affect?

A

It is a viral pathogen and it affects plants

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9
Q

What type of pathogen/disease is Black Sigatoka and what does it affect?

A

It is a fungal pathogen and it affects banana plants

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10
Q

What type of pathogen/disease is Ringworm and what does it affect?

A

It is a fungal pathogen and it affects cattle

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11
Q

What type of pathogen/disease is Athlete’s foot and what does it affect?

A

It is a fungal pathogen and it affects humans

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12
Q

What type of pathogen/disease is Potato/tomato blight and what does it affect?

A

It is a protozoa pathogen and it affects potatoes/tomatoes

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13
Q

What type of pathogen/disease is Malaria and what does it affect?

A

It is a protozoa pathogen and it affects animals- including humans.

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14
Q

What is direct transmission?

A

Direct transmission is when a disease is transmitted directly from one organism to another. Direct transmission can happen in several ways, including droplet infection (coughing and sneezing tiny droplets of mucus or saliva onto someone), sexual intercourse, or touching an infected organism.
- HIV through sexual intercourse
- Athletes’s foot via touch

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15
Q

What is indirect transmission?

A

Indirect transmission is when a disease is transmitted from one organism to another via an intermediate. Intermediates include air, food, water, or another organism (known as a vector)
- potato/tomato blight through spores in the air and water
- malaria through mosquitoes

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16
Q

How do overcrowded conditions increase the transmission of communicable diseases?

A

Example TB:
TB is spread directly via droplet infection. It’s also spread indirectly because the bacteria can remain in the air for long periods of time and infect new people. The risk of TB infection is also increased when lots of people live crowded together in a small space.

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17
Q

How can climate affect the spread of communicable diseases?

A

Example Potato/tomato blight:
It is especially common during wet summers because the spores need water to spread.
Example Malaria:
Malaria is the most common in tropical countries, which are humid and hot. This is because these are the ideal conditions for mosquitoes to breed

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18
Q

How can- for humans- social factors affect the transmission of communicable diseases?

A

Example HIV:
Lack of access to good healthcare can mean that people are less likely to be treated or diagnosed with the disease. Or to be given the most effective drugs and they are less available so the disease is more likely to be passed on to others.
Lack of access to good health education can mean that people are less likely to know how HIV is transmitted and how it can be avoided, meaning it is more likely to accidentally be passed on to others.

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19
Q

What are antigens?

A

Antigens are molecules (usually proteins or polysaccharides) found on the surface of cells. When a pathogen invades the body, the antigens on its cell surface are identified as foreign, which activates cells in the immune system.

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20
Q

What are the specific and non-specific stages in the immune response?

A

The non-specific response happens in the same way for all microorganisms- whatever foreign antigens they have. The specific response is antigen-specific- it is aimed at specific pathogens. It involves white blood cells called T and B lymphocytes.

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21
Q

What is a phagocyte?

A

A phagocyte is a type of white blood cell that carries out phagocytosis. They’re found in the blood and in tissues and carry out a non-specific immune response.

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22
Q

How do phagocytes work?

A
  1. A phagocyte recognizes the antigens on a pathogen
  2. The cytoplasm moves around the pathogen, engulfing it. This can be made easier by the presence of opsonins
  3. The pathogen is now contained in a phagosome in the cytoplasm of the phagocyte
  4. A lysosome fuses with the phagosome. The enzymes break down the pathogen.
  5. The phagocyte then presents the pathogen’s antigens. It sticks the antigens on its surface to activate other immune system cells. When a phagocyte does this it is acting as an antigen-presenting cell
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23
Q

What are opsonins?

A

They are molecules in the blood that attach to foreign antigens to aid phagocytosis. Some hide the negative changes on the membrane of the pathogen, making it easier for the negatively charged phagocytes to get closer to the pathogen.

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24
Q

What are neutrophils?

A

Neutrophils are a type of phagocyte. They’re the first white blood cells to respond to a pathogen inside the body. Neutrophils move toward a wound in response to signals from cytokines. The cytokines are released by cells at the site of the wound.

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25
Q

What are T lymphocytes?

A

A T lymphocyte is another type of white blood cell. Their surface is covered with receptors. The receptors bind to antigens presented by APCs

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26
Q

How do T lymphocytes work?

A

Each T lymphocyte has a different receptor on its surface. When the receptor on the surface of a T lymphocyte meets a complementary antigen, it binds to it- so each T lymphocyte will bind to a different antigen. This activates the T lymphocyte- the process is called clonal selection. The T lymphocyte then undergoes clonal expansion- it divides to produce clones of itself. Different types of T lymphocytes carry out different functions.

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27
Q

What do T helper cells do?

A

T helper cells release substances to activate B lymphocytes and T killer cells.

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28
Q

What do T killer cells do?

A

T killer cells attach to and kill cells that are infected with a virus.

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29
Q

What do T regulatory cells do?

A

T regulatory cells suppress the immune response from other white blood cells. This helps to stop immune system cells from mistakenly attacking the host’s body cells.

30
Q

What are B lymphocytes?

A

B lymphocytes are another type of white blood cell. They are covered with proteins called antibodies. Antibodies bind to antigens to form an Antigen-antibody complex.

31
Q

How do B lymphocytes work?

A

Each B lymphocyte has a differently shaped antibody on its surface. When the antibody on the surface of a B lymphocyte meets a complementary-shaped antigen, it binds to it - so each B lymphocyte will bind to a different antigen. This together with substances released from T helper cells, activates the B lymphocyte. This process is another example of clonal selection. This activated B lymphocyte divides, by mitosis, into plasma cells and memory cells. This is another example of clonal expansion.

32
Q

How does cell signaling work?

A
  • Cell signalling is how cells communicate
  • A cell may release a substance that binds to the receptors on another cell- this causes a response of some kind in the other cell.
  • Cell signalling is really important In the immune response because it helps to activate all the different types of white blood cells that are needed.
  • For example, T helper cells release interleukins that bind to receptors on B lymphocytes. This activates the B lymphocytes- the T helper cells are signalling to the B lymphocytes that there is a pathogen in the body.
33
Q

What are plasma cells?

A

Plasma cells are clones of the B lymphocyte. They secrete loads of the antibody, specific to the antigen, into the blood. These antibodies will bind to the antigens on the surface of the pathogen to form lots of antigen-antibody complexes.

34
Q

What is the structure of Antibodies?

A

Antibodies are glycoproteins made of four polypeptide chains- two heavy chains and two light chains. Each chain has a variable region and a constant region.
- the variable regions of the antibody form the antigen binding sites. The shape of the variable region is complementary to a particular antigen. The variable regions differ between antibodies.
- the hinge region allows flexibility when the antibody binds to the antigen
- the constant regions allow binding to receptors on immune system cells. The constant region is the same in all antibodies.
- Disulfide bridges hold the polypeptide chains of the protein together.

35
Q

How does the process of agglutinating pathogens help to clear an infection?

A

Each antibody has two binding sites, so an antibody can bind to two pathogens at the same time, and the pathogens become clumped together. Phagocytes then bind to the antibodies and phagocytes a lot of pathogens all at once. Antibodies that behave this way are known as agglutinins.

36
Q

How does the process of neutralizing toxins help to clear an infection?

A

Like antigens, toxins have different shapes. Antibodies called anti-toxins can bind to the toxins from affecting human cells, so the toxins are neutralized. The toxin antibody complexes are also phagocytosed.

37
Q

How does the prevention of pathogen binding to human cells help to clear an infection?

A

When antibodies bind to the antigens on pathogens, they may block the cell surface receptors that the pathogens need to bind to the host cells. This means the pathogen can’t attach to or infect the host cells.

38
Q

Why is the primary response to a pathogen slow?

A
  • there arent many B lymphocytes that can make the antibody needed to bind to it
  • eventually, the body will produce enough antibodies to overcome the infection- but the person may be showing symptoms already
  • after infection by T and B lymphocytes produce memory cells which remain in the body for a long time
  • Memory T lymphocytes remember the specific antigens and will recognize them faster and produce more antibodies the second time around.
39
Q

Why is the secondary response to a pathogen faster?

A
  • Clonal selection happens faster. Memory B lymphocytes are activated and divide into plasma cells that produce the right antibody to the antigen. Memory T lymphocytes are activated and divide into the correct type of T lymphocytes to kill the cell carrying the antigen.
  • The secondary response often gets rid of the pathogen before you begin to show symptoms.
40
Q

What is a blood smear and what may you see?

A

A blood smear is a sample of blood smeared over a microscope slide. Stains are added to the sample to make the different cells easy to see. When looking at a blood smear you’re likely to see red blood cells, white blood cells, and platelets. Some types of white blood cells have granules in their cytoplasm and other types don’t.

41
Q

What is active immunity?

A

This is the type of immunity you get when your immune system makes its own antibodies after being stimulated by an antigen. There are two different types of active immunity.
Natural: This is when you become immune after catching a disease.
Artificial vaccination: This is when you become immune after you’ve been given a vaccination containing a harmless dose of antigen.

42
Q

What is passive immunity?

A

This is the type of immunity you get from being given antibodies made by a different organism- your immune system doesn’t produce any antibodies of its own. There are two types:
Natural: This is when a baby becomes immune due to the antibodies it receives from its mother, through the placenta and in breast milk.
Artificial: This is when you become immune after being injected with antibodies from someone else.

43
Q

What is an autoimmune disease?

A

Sometimes, an organism’s immune system isn’t able to recognize self-antigens. When it happens, the immune system treats the self-antigens as foreign antigens and launches an immune response against the organism’s own tissues. They are usually chronic and they can often be treated- not cured.

44
Q

What is Lupus?

A

Lupus is caused by the immune system attacking cells in the connective tissues. This damages the tissues and causes painful inflammation. Lupus can affect the skin and joints, as well as organs such as the heart and lungs.

45
Q

What is Rheumatoid arthritis?

A

Rheumatoid arthritis is caused by the immune system attacking cells in the joints. This causes pain and inflammation.

46
Q

What are vaccines and what is their function?

A

Vaccines contain substances that cause your body to produce memory cells against a particular pathogen, without the pathogen causing disease. This means you become immune without getting any symptoms.

47
Q

What are epidemics and how can they be prevented?

A

Epidemics are mass outbreaks of disease and they can be prevented if a large percentage of the population is vaccinated. That way, even people who haven’t been vaccinated are unlikely to get the disease, because there’s no one to catch it from. This is called herd immunity.

48
Q

What is in a vaccine and how does it work?

A

The substances in a vaccine may be antigens, which could be free or attach to a dead or attenuated pathogen. The substances can also be other molecules, such as mRNA, designed to code for antigens found on a pathogen. When the mRNA enters the body cells, it provides the instructions needed for the cells to produce these antigens, which trigger memory cells to be made.

49
Q

What are booster vaccines?

A

They are often given later on to make sure memory cells are produced

50
Q

Why is vaccination not the same as immunization?

A

Vaccination is the administration of a substance designed to stimulate the immune system. Immunization is the process by which you develop immunity.

51
Q

What is the MMR vaccine?

A

The MMR protects against measles, mumps, and rubella. The MMR is usually given to children as an injection around a year old, and again before they start school. It contains attenuated measles, mumps, and rubella virus.

52
Q

What is the Meningitis C vaccine?

A

It protects against the bacteria that causes Meningitis C. It is first given as an injection to babies at 3 months. Boosters are then given to 1-year-olds and teenagers.

53
Q

Why does the influenza vaccine change each year?

A

The vaccine changes each year, because the antigens on the surface of the virus change regularly, forming new strains of the virus.
- Therefore memory cells won’t recognize them (immunologically distinct)
- Each year there are different strains circulating
- Laboratories collect different strain samples (WHO, CDC) and they test the effectiveness of different vaccines against them
- New vaccines are developed each year
- Governments have a program of vaccination using the most suitable vaccine.

54
Q

What are antibiotics?

A

Antibiotics are chemicals that kill or inhibit the growth of bacteria. They’re useful because they can target bacterial cells without damaging human body cells.
Penicillin was the first antibiotic to be isolated and mass-produced.

55
Q

What are the risks of using antibiotics?

A
  • side effects
  • severe allergic reactions
  • antibiotic resistance
56
Q

How do bacteria gain antibiotic resistance?

A
  • some genetic mutations can make them naturally resistant to an antibiotic
  • this is an advantage as they survive, even when others die from the antibiotic
  • they can then reproduce many more times, passing on this advantageous allele and increasing the allele population.
  • it spreads and becomes more common over time
57
Q

Why is antibiotic resistance bad?

A
  • You can’t easily get rid of infections with antibiotics when people are ill
  • Increased use of antibiotics means that antibiotic resistance is increasing. Superbugs that are resistant to most known antibiotics are becoming more common. This means we are less able to treat some potentially life-threatening bacterial infections.
58
Q

What is MRSA?

A

It causes severe wound infections and it is resistant to several antibiotics, including meticillin.

59
Q

What is Clostridium difficile?

A

It infects the digestive system, usually causing problems in people who have already been treated with antibiotics. It is thought that the harmless bacteria that are normally present in the digestive system are killed by the antibiotics, which C.difficile is resistant to. This allows it to flourish. It also produces a toxin that causes severe diarrhea, fever, and cramps.

60
Q

What are doctors doing to prevent the growth of superbugs?

A
  • reduce the use of antibiotics
  • not to prescribe for minor infections
  • not to prescribe to prevent infections
  • patients are advised to take all they are prescribed to make sure the infection is fully cleared.
61
Q

Where do many medicinal drugs come from?

A

They are manufactured using natural compounds found in plants. animals or microorganisms.
- we have much yet to explore so there may be compounds that can treat disease or produce new antibiotics for currently incurable diseases.
- Possible sources of drugs need to be protected by maintaining the biodiversity on earth. (some could die out before we discover them)
- Even ones already studied could still prove useful sources of medicines as new techniques for extraction and purification are developed.

62
Q

What are personal medicines?

A
  • your genes determine how you react to different drugs, so everyone reacts differently
  • personalized medicines are medicines that are tailored to an individual’s DNA. If doctors have your genetic information, they can use it to predict how you will respond to different drugs and only prescribe the ones that will be most effective.
  • scientists hope that by studying the relationship between someone’s genetic makeup and the responsiveness to drugs more effective drugs can be produced in the future.
63
Q

What is synthetic biology?

A
  • Synthetic biology involves using technology to design and make things like artificial proteins, cells, and even microorganisms.
  • It has applications in lots of different areas, including medicine. For example, scientists are looking at engineering bacteria to destroy cancer cells, while leaving healthy body cells intact.
64
Q

How does skin prevent infection?

A
  • physical barrier preventing entry
  • produces antimicrobial chemicals that can lower pH and inhibit the growth of pathogens
65
Q

How do mucus membranes prevent infection?

A
  • protect body openings
  • some can secrete mucus to trap pathogens
  • mucus can contain antimicrobial enzymes
66
Q

How does blood clotting prevent infection?

A
  • it is a mesh of protein/fibrin
  • it plugs wounds and reduces pathogen entry and blood loss
  • they are formed by a series of chemical reactions when platelets are exposed to damaged blood vessels
67
Q

How does inflammation prevent infection?

A
  • it can be triggered by tissue damage
  • the damaged tissue releases molecules that increase the permeability of the surrounding blood vessels
  • this means more fluid is directed here leading to swelling and hot
  • this also isolates the pathogen
68
Q

How does wound repair prevent infection?

A
  • the skin is able to repair itself
  • the edges migrate to create a layer of skin over the top via mitosis and migrating
  • the tissue is then repaired under, without pathogens being able to enter
69
Q

How do expulsive reflexes prevent infection?

A
  • sneezing etc
  • occurs when the mucus membranes are irritated so the body expels the irritant and possible pathogen
  • this is an automatic response
70
Q

What is the purpose of the waxy cuticle in plants?

A

It provides a physical barrier against pathogen entry. It may also stop water collection on the leaf , which could reduce the risk of infection by pathogens that are transferred between plants in water.

71
Q

What benefit does the plant cell wall provide?

A

It provides a physical barrier for any pathogens that make it through the waxy cuticle.

72
Q

What is the purpose of callose deposition?

A
  • Plants produce a polysaccharide called callose during times of stress
  • Callose gets deposited between the cell walls and the cell membrane to make it harder for pathogen to enter the cell
  • it is also deposited in plasmodemata and sieve plates to prevent spread between cells
73
Q

What chemical defenses do plants have against pathogens?

A
  • they produce antimicrobial chemicals which kill pathogens or inhibit their growth
  • some chemicals secreted by plants are toxic to animals/insects which reduces the amount of insect vectors

Biology (26 decks)

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