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OCR A Level Biology > Immune and Disease > Flashcards

Immune and Disease Flashcards

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1
Q

State the definition of disease

A

-impairs normal function of an organisim

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2
Q

state the definition of a pathogen

A

a microorganisms that causes disease

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3
Q

what diseases are caused by bacteria

A
  • bacterial meningitis
  • tuberculosis (TB)
  • Ring rot potato
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4
Q

what diseases are caused by fungi

A
  • Athletes foot
  • Ringworm
  • Black sigatoka
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5
Q

what diseases are caused by virus

A
  • HIV
  • Influenza
  • Tobacco mosaic virus
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6
Q

what diseases are caused by Protista

A
  • Malaria

- Tomato late blight

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7
Q

How can diseases be transmitted directly

A
  • Direct contact (kissing, touching)
  • inoculation (makeup brushes, needles)
  • Ingestion
  • droplet infection
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8
Q

How can diseases be transmitted indirectly

A
  • Fomites
  • Vectors
  • spores
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9
Q

What factors can affect transmission

A

Living conditions
-Overcrowding can increase transmission of disease
Example is TB, spread through droplet infection

Social Factors

  • such as income, occupation and area
  • sometimes can be hard to access good healthcare (people may be less likely to get diagnosed, treatment may be hard to obtain etc)
  • good health education (telling people how certain diseases can spread and how to avoid that

Climate

  • Potato late blight is common during wet summers because spores need water to spread
  • Malaria spreads in hot humid conditions because this ideal for mosquitoes to bread
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10
Q

How does the skin act as a primary defence mechanism

A
  • Physical barrier
  • main primary defence
  • Dead skin cells act as a barrier
  • secrete lysozymes which catalyses breakdown of bacterial cell walls
  • can secrete fatty acids that can kill bacteria and also lower pH of skin to make conditions unfavourable
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11
Q

How do mucus membranes act as a primary defence mechanism

A
  • Protect openings that are exposed to environment (mouth, nostrils, ears etc)
  • Cilliated cells waft mucus up your airway to be swallowed
  • goblet cells secrete mucus which traps microorganisms and contains phagocytes and lysozymes
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12
Q

What is an expulsive reflex and how do they act as a primary defence mechanism

A
  • Coughing and sneezing, same with vomitting and diahorea

- help expel pathogen from body

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13
Q

How does blood clotting and wound repair work

A
  • Blood clots because skin is broken
  • The platlets then interact with the collagen to make a blood clot
  • collagen secretes thromoplastin and sertanonin to help blood clot and reduce blood flow
  • clot dries scab forms

Wound repair

  • epitheli cells below the scab start to grow, collagen fibres deposited to give new tissue strength
  • skin grows and scabs shrinks, edges of laceration are pulled together
  • if there are too many collagen fibres you end up with scar
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13
Q

How does blood clotting and wound repair work

A
  • Blood clots because skin is broken
  • The platlets then interact with the collagen to make a blood clot
  • collagen secretes thromoplastin and sertanonin to help blood clot and reduce blood flow
  • clot dries scab forms

Wound repair

  • epitheli cells below the scab start to grow, collagen fibres deposited to give new tissue strength
  • skin grows and scabs shrinks, edges of laceration are pulled together
  • if there are too many collagen fibres you end up with scar
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14
Q

How does inflammation work

A
  • mast cells activate histamines and cytokines
  • histamines make blood vessles dilate, which causes heat and redness. High temp means pathogen can’t reproduce
  • also blood walls are more leaky, which increases perembality so tissue fluid leakes out causing swelling (odema) which isolates any pathogens
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15
Q

What primary defences do plants have

A

Physical

  • waxy cuticle provides barrier against pathogens. Also stops water collecting on leaf which reduces risk of infection as water is a vector
  • Surrounded by cell wall
  • proudce callose which is deposited between plant cell walls and plasma membrane when pathogen enters
  • callose deposition at plasdostmta limits the pathogen from travelling into neighbouring cells

Chemical

  • Saponins which can destroy cell membranes of fungi
  • phytoalexins which inhibit growth of fungi

also there chemicals can be secreted to stop insects

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16
Q

Outline how phagocytosis occurs

A
  • recognises there is a foreign body in cell
  • Opsonins highlight pathogens and cytokines alert neutrophills

the process

  • cytoplasm of neutrophill/macrophage moves around pathogen to engluf it
  • Pathogen is now in a phagosome
  • this fuses with a lysosome to make a phagolysosome (the hydrolytic enzyme breaks down pathogen)

In a macrophage
-It will present the pathogens on cell surface membrane to act as an antigen presenting cell (APC)

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17
Q

How does the immune response work

A

APC goes to find the t-cell with a complimentary receptor to the antigen

  • this is called clonal selection
  • then clonal expansion happens through mitosis
  • t-helper cells activate b-lympocytes and t-killer cells
  • this activates t-killer cells which an destroy pathogen by attaching to cell taken over by a virus
  • t-regulatory cells which suppress immune response from there wbc
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18
Q

What happens during B-lymphocyte activation

A
  • T helper cells activates b lymphcytes by releasing interleukins
  • clonal selection happens where b lymphocyte with antibodies is selected
  • b lymphocytes contain antibodies, which can form an antibody-antigen complex
  • correct b lymphocyte divides into plasma cells and memory cells by clonal expansion via mitosis
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19
Q

What do plasma cells produce

A

Opsinins
antitoxins
antibodies

20
Q

What is the structure of an antibody

A

antibody is a glycoprotein
-made from 4 polypeptide chains 2 light two dark

It has a
-variable region: antigen binding site, shape is complimentary to antigen
-constant region: same in antibodies but the function is it allows for phagocytes to bind
-hinge region:allows for flexibility when binding to antigen
-

20
Q

What is the structure of an antibody

A

antibody is a glycoprotein
-made from 4 polypeptide chains 2 light two dark

It has a

  • variable region: antigen binding site, shape is complimentary to antigen
  • constant region: allows binding of receptors on immune cells, reigon is same in all antibodies (made up of same sequence of amino acids)
  • hinge region: allows for flexibility when binding to antigen
  • Disulfide bridge: holds polypeptide chain together
20
Q

What is the structure of an antibody

A

antibody is a glycoprotein
-made from 4 polypeptide chains 2 light two dark

It has a
-variable region: antigen binding site, shape is complimentary to antigen
-constant region: allows binding of receptors on immune cells, reigon is same in all antibodies (made up of same sequence of amino acids)
-hinge region:allows for flexibility when binding to antigen
-

21
Q

What are the roles of antibodies

A
  1. Aggultination
    - this is when pathogens can clump together, to make it easier for phagocytes to engulf it
  2. Neutralsing toxins
    - antitoxins can bind onto toxins from pathogens. This prevents it from affecting human cells
  3. Act as opsinins
    - highlight pathogens to make them more visible to phagocytes
22
Q

What is the primary immune response

A
  • This is when the antigen activates the immune system
  • Humoural and cell mediated
  • Primary response is slow due to clonal selection and expansation (not enough b lymphocytes that can make antibodies needed)
  • can cause symptoms
23
Q

What is the role of t memory cells

A

remember specific antigen and can recognise it the 2nd time

24
Q

What is the role of b memory cells

A

records specfic antibodies needed to bind onto antigens

25
Q

What is the secondary immune system

A
  • if the same pathogen enters immune response will be quicker and stronger
  • clonal selection is faster
  • memory b cells can divide into plasma cells
  • memory t cells are activated ( divide into t lymphocytes to kill the pathogen)
  • secondary immune system gets rid of pathogen before symptoms
26
Q

Why does immunity not last forever

A
  • memory b and t cells have a limited lifespan
  • when they die, a person may be susceptible to attacks again
  • Immunity can be maintained by being continually exposed to pathogen so you make more b and t memory cells
27
Q

What is active immunity

A

type of immunity where your body makes its own antibodies after being stimualted by antigen

28
Q

What are the two types of active immunity and give an example

A

Natrual :immune after having the disease (e.g after getting measles as a child and getting it again)

Artifical:become Immune after a vaccine

29
Q

What is passive immunity

A

Immunity obtained from being given antibodies made from another organism

so its not your own antibodies

30
Q

What are two types of passive immunity and give examples

A

Natural: when baby becomes immune due to antibodies it receives from mother (from breastmilk)

Artificial: when you become immune from being injected with somebody else antibodies (e.g if you get tetanus your injected with antibodies from blood donations)

31
Q

Can you compare passive and active immunity

A
  • active immunity requires exposure to antigen but passive doesn’t
  • for passive immunity protection is immediate but for active it takes some time
  • active immunity protection is long term whereas in passive it’s short term
  • in active immunity memory cells are produced but not in passive immunity
32
Q

What does an autoimmune disease do

A

It attacks the bodies own cells

33
Q

Give examples of autoimmune diseases

A

Lupus: autoimmune disease that attacks connective tissues, damage causes painful inflammation. Lupus can affect skin, joints, hearts and lungs

Rheumatoid arthritis: when immune system attacks cells the joints, causes inflammation and pain.

Type 1 diabetes

34
Q

How can you get a vaccine into your body

What do vaccines contain

A
  • they can be taken injected or taken orally
  • Vaccines contain antigens that can cause an immune response
  • the antigens can be weakened, isolated, free, or attached
35
Q

What is the disadvantage of taking vaccines orally

A
  • can be broken down by enzymes in the gut

- or the vaccine can be too large to absorb into blood

36
Q

What is herd immunity

A

when unvaccinated people are protected against the vaccine due to the occurrence of disease is reduced by vaccinated people

37
Q

What routine vaccines do we take

A

the MMR vaccine: taken around 1-year-olds, contains attenuated (weakened) measles, mumps and rubella

the meningitis c vaccine: given at 3 months and at 1 year

38
Q

Why are new vaccines developed every year

A

The influenza virus can change the antigens on its surface
so every year there is a new vaccine made
-their effectiveness is tested by WHO and the CDC
-the one that’s chosen is most effective against that years influenza

39
Q

What is an antibiotic

A

chemicals that inhibit and kill bacteria

40
Q

Who discovered antibiotics and what was the name of the antibiotic

A

Alexander Fleming

Penacilin

41
Q

What are the risks of antibiotics

A
  • side affects
  • can cause severe allergic reactions
  • antibiotic resistance
42
Q

When did antibiotic resistance become widespread

A

mid-twentieth century

43
Q

Give two examples of bacteria resistant to antibiotics

A

MRSA: causes serious wound infections, resistance to methicillin

Clostridium difficile: affects digestion system, produces toxins which cause diarrhoea

44
Q

How can you prevent antibiotic resistance

A

-doctors encourage to reduce use of antibiotics only give it when needed not as a prevention
-patients advised to take full course of antibiotics to kill all bacteria
-

45
Q

What is synthetic biology

A

involves technology to design and make artificial proteins, cells and microorganisms

for example scientist that engineer bacteria destroy cancer cells whilst leaving healthy body cells intact

46
Q

What is personalised medicine

A

medicines that are tailored to one’s DNA

the theory is we can use it to predict how we will respond to different medicines
help only to prescribe ones that will work for you

OCR A Level Biology (24 decks)

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