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Biology > 4.1 - Communicable diseases > Flashcards

4.1 - Communicable diseases Flashcards

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1
Q

What are pathogens?

A

Microorganisms that cause disease

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2
Q

What are the main types of pathogens?

A
  • Bacteria
  • Viruses
  • Fungi
  • Protists (Protoctista)
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3
Q

How do bacteria cause diseases?

A
  • By producing toxins (Proteins)

- The toxins reproduce by binary fission (Very fast)

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4
Q

What are some examples diseases and their bacterium?

A
  • Tuberculosis is caused by Mycobacterium tuberculosis
  • Bacterial meningitis
  • Ring rot (In plants)
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5
Q

What is used to treat bacterial diseases?

A

Antibiotics

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6
Q

How are antibiotics tested for development?

A
  • Bacteria cultures are placed on an agar plate
  • Different antibiotics are tested to see their affect
  • Clear area is the zone of inhibition, this is where the bacteria either cannot grow or are killed
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7
Q

What is antibiotic resistance?

A
  • Natural selection occurs
  • This is when an antibiotic is used causing the weaker bacterium to be killed which leaves the stronger bacteria alive
  • The stronger bacteria will reproduce causing a new culture of antibiotic resistant bacterium
  • The resistance then develops over time, the more we use antibiotics, the more bacteria become resistant
  • By not finishing a course of antibiotics it can encourage antibiotic resistant bacteria because the stronger bacterium are not killed at the end of the course
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8
Q

How do viruses cause diseases?

A
  • Viruses take over cells and reproduce rapidly inside of them
  • They are not alive
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9
Q

What is the structure of a virus?

A
  • Proteins on the surface of the virus that help it to get into cells by binding to the receptors on the cells surface
  • Some viruses have a lipid membrane around the outside
  • Capsid, protein coat
  • Nucleic inside containing genetic code (RNA or DNA)
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10
Q

How does hand washing kill viruses?

A
  • The detergent breaks down the lipid membrane

- This makes the viral particle non-functional

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11
Q

How is the lipid membrane formed?

A
  • The virus will enter a cell and reproduce

- When exiting they take a coat of the cell surface membrane with them to form their lipid membrane

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12
Q

What are some examples diseases caused by a virus?

A
  • HIV (Retrovirus, meaning that it inserts the DNA into the genome in the nucleus)
  • Flus, Corona virus
  • Tobacco mosaic virus (In plants)
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13
Q

How does fungi cause diseases?

A
  • Long tubed like structures called hyphae extend up the organism to form mould
  • Extra cellular enzymes are released, these enzymes go into the surroundings and digest the nutrients so the hyphae can absorb it and grow
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14
Q

What is mycelium?

A

When many long, tubed like structure called hyphae are formed it then becomes mycelium

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15
Q

What are some examples of diseases caused by fungi?

A
  • Athletes foot
  • Ring worm (In humans and cattle)
  • Black sigatoka (In plants)
  • The panama disease (In bananas)
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16
Q

What are protists?

A

Eukaryotic organisms that are generally single celled

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17
Q

How do protists cause disease?

A
  • Protists enter host cells

- They feed on the contents as they grow

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18
Q

How does malarial parasite work?

A

Malaria goes into the RBC’s and feeds on the haemoglobin

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19
Q

What are some examples of diseases caused by protists?

A
  • Malaria
  • Potato or tomato blight
  • Sleeping sickness
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20
Q

What is transmission?

A

Passing a pathogen from person to person

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21
Q

How is transmission caused?

A
  • Direct contact
  • The exchange of fluids (Sexual intercourse, blood transfusions or needles)
  • Faecal-oral transmission (Contamination)
  • Airborne (Droplet infection from sneezing or coughing or if something is truly airborne it can remain in the air for much longer and be transmitted in this way) [E.g spores which are tough and durable versions of the pathogens that can be carried in the air]
  • Via a vector (Indirect transmission, when something is needed to help spread the pathogen) [E.g malaria, the vectors are mosquitos]
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22
Q

What are some examples of diseases which are transmitted in all the different ways?

A
  • Direct contact: Meningitis, ringworm or athletes foot
  • Exchange of fluids: HIV
  • Faecal-oral: Cholera or food poisoning
  • Airborne (Droplet infection): Corona virus
  • Airborne (Spores): Anthrax, the spores survive in the soil for many years
  • Truly airborne: Measles
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23
Q

What is the R number?

A

-The rate of transmission

The average number of people that are infected by one person with the pathogen

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24
Q

What is the life cycle of the malarial parasite?

A
  • A pregnant female mosquito feeds on blood
  • As the feed on the blood, some saliva containing a malarial parasite is inserted into the capillaries
  • The malarial parasite is now in the blood flow of the person
  • The parasite follows the blood flow until it reaches the liver
  • The parasite then enters the liver and it infects the cells inside it
  • The parasite reproduces rapidly inside the cell and then exits to try and colonise blood cells
  • As the parasite exits the cells it causes a fever
  • The parasite then enters and exits red blood cells, the exiting causes the person to develop waves of bad fevers
  • Once the parasite bursts out the RBC’s it also forms gametes to be produced
  • This means that when mosquitos feed on the blood of this person they take up the gametes to form new parasites. These new parasites are then injected into a different person when the mosquito feeds on their blood
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25
Q

What is the name of a common type of malarial parasite?

A

Plasmodium Falciparum

26
Q

How does climate affect transmission?

A
  • Bacteria and fungi can replicate quicker in warmer conditions
  • Mosquitos only live in climates that are warmer and where there is water for them to lay their eggs (To breed)
27
Q

What are the different types of plant defences to pathogens?

A
  • Passive physical defences (The outer barrier)

- Chemical defences (Chemicals used to defend the plants from pathogens)

28
Q

What are the passive physical plant defences?

A
  • Cellulose (Tough, protects cells)
  • The waxy cuticle (Impermeable)
  • Bark (To stop pathogens from entering the tree trunk)
  • Stomatal closing (To stop pathogens from entering)
  • Callose (Blocks the phloem and the sieve plates so that the pathogen cannot transport through the plant)
  • Tylose (Blocks the xylem so that the pathogen cannot transport through the plant)
29
Q

What are the chemicals plant defences?

A
  • Terpenoids (Menthols)
  • Phenols (Tannins)
  • Alkaloids (Caffeine, nicotine and cocaine used by plants for defence)
  • Defensins
  • Hydrolytic enzymes (Enzymes that break down pathogens once they enter the cell) [Used for breaking down fungal pathogens that are potentially growing through the plants roots or leaves]
30
Q

What are primary defences in humans?

A

Defences that prevent pathogens entering the body

31
Q

What are the different primary defences in humans?

A
  • Skin (Contains keratin to make it impermeable)
  • Clotting (Prevents pathogens entering the body)
  • Mucous membranes (In the lungs and in the digestive system)
  • Earwax
  • Tears (Contain the enzymes lysozyme which digests bacterial cell walls)
  • Stomach acid
  • Coughing + sneezing to eject particles out of the lungs
32
Q

What is the response to getting a cut on the skin?

A
  • A clotting response is triggered
  • Collagen is exposed and it comes into contact with the blood as there is damage in the cells
  • This starts an enzyme cascade (One enzyme is turned on to catalyse the formation of more enzymes and then even more enzymes etc) [Amplification]
  • Platelets can detect the collagen
  • The amplification of enzymes causes the inactive protein, fibrinogen to be converted into an active net of the protein fibrin
  • This creates a clot of red blood cells and platelets in a mesh of fibrin fibres
33
Q

How do mucous membranes work to defend the body from pathogens?

A
  • Mucous membranes trap the bacteria in mucus that is made in mucous secreting glands and released from goblet cells
  • Ciliated epithelial cells then waft the mucous with the pathogens/bacteria to the throat so then the mucous can either be digested or coughed out
  • Mucous membranes have a good blood supply, immune surveillance and patrolling macrophages to aid the process of removing pathogens from the body
34
Q

What is inflammation?

A

-Diverting blood flow to an area which is infected or damaged

35
Q

What is the process of inflammation?

A
  • Damage is done to the skins collagen fibres
  • This releases signals in the local area which causes more blood flow to these areas (Vasodilation)
  • This then causes neutrophils to move to the damaged tissue area from the capillaries
36
Q

What is a secondary defence in humans?

A
  • Phagocytosis (Non-specific)

- Inflammation (Non-specific)

37
Q

What are the different types of phagocytes?

A
  • Neutrophils

- Macrophages

38
Q

What are the features of neutrophils?

A
  • Live in the blood and move to the tissue when needed
  • Have a multi-lobed nucleus, to allow them squeeze out of the capillary into the tissue
  • Produced in the bone marrow
  • Contain lots of lysosomes
39
Q

What are the features of macrophages?

A

-Phagocytes that patrol the tissues waiting to engulf pathogens

40
Q

What is the process of phagocytosis?

A
  • A neutrophil binds to the surface of the pathogen via a complimentary antibody or due to a signal
  • The phagocyte engulfs the pathogen to form a phagosome
  • The lysosomes release digestive enzymes to then fuse with the phagosome
  • The digestive enzymes digest the pathogen inside of the phagolysosome
  • The left over nutrients are then absorbed back into the phagocyte
41
Q

What is the structure of a red blood cell (Erythrocyte)?

A
  • Biconcave shape

- No nucleus

42
Q

What is the structure of a white blood cell (Lymphocyte)?

A

-Large nucleus that takes up most the space inside of the cell

43
Q

What is the structure of monocytes (Macrophages inside the blood)?

A
  • Larger cell size

- Large nucleus

44
Q

How are specific secondary responses different to non-specific secondary responses?

A
  • Specific responses will have a tailored/specific response to the pathogen
  • This is due to antigen presenting cells
45
Q

What is the process of the specific immune response?

A
  • A pathogen with an antigen on the surface is eaten by a macrophage
  • The antigens from the pathogen are then presented on the surface of the macrophage
  • The macrophage then travels to the lymph nodes where it shows the antigens to a range of cells
  • Cells that can recognise the antigen are then selected (Clonal selection)
  • The selected cells then divide via mitosis to produce many cells that can recognise the antigen (Clonal expansion)
  • Clonal expansion can occur with both T killer cells or T helper cells
46
Q

What is the function of T killer cells?

A
  • T killer cells attack infected cells to destroy the pathogen
  • They do this by touching the infected cells with a death ligand to trigger apoptosis (Programmed cell death)
47
Q

What is the function of T helper cells?

A
  • T helper cells can activate B lymphocytes
  • The B lymphocytes that can recognise the antigen can then divide
  • T helper cells can also sometimes produce T memory cells
48
Q

What is the function of B lymphocytes?

A
  • B lymphocytes are activated by T helper cells
  • The B lymphocytes that can recognise the antigen then divide
  • This produces an active B cell which can differentiate into either a plasma cell or a B memory cell
49
Q

What is the function of a plasma cell?

A
  • A plasma cell produces antibodies that are needed to recognise antigens on pathogens so the pathogens can be identified and killed
  • Plasma cells contain a lot of ribosomes to make the antibodies, because antibodies are proteins
50
Q

What are cytokines?

A
  • Cytokines are signalling molecules released by the T helper cells
  • The cytokines stimulate the other components of the immune systems
51
Q

What is the structure of antibodies?

A
  • Variable region at the top, the shape is unique to the antibody and it needs to be complimentary to the antigen (This complimentary, unique shape is part of the reason that the antibody is part of the specific immune response)
  • Constant region, same shape so that it can interact with other cells in the immune system. It can signal to phagocytes for example (Opsinisation)
  • 4 polypeptide chains (2 heavy and 2 light)
  • Held together via disulphide bridges which stabilises the structure
  • Hinge region connecting the heavy chains, this allows flexibility so it is easier to bind to antigens (Flexible part of the protein improves, the binding ability)
52
Q

What is opsonisation?

A
  • When an antibody binds to an antigen and signals to a phagocyte that there is a foreign pathogen. This then results in the pathogen being engulfed via phagocytosis
  • The antibody is working as an opsonin
53
Q

What is agglutination?

A

-Sticking pathogens together so that they are easier to engulf and so they cannot infect the body cells

54
Q

What are the ways that an antibody works

A
  • Opsonisation
  • Agglutination
  • Inactivation
55
Q

What is inactivation?

A
  • When the antibody sticks to a key protein on the surface of the pathogen
  • This stops it from being able to infect cells for example
  • Antibodies can also inactivate the toxins of bacterium (Working as an antitoxin)
56
Q

What is the purpose of T regulator cells?

A

Cells that bring down an immune response once it is no longer needed

57
Q

Why is the secondary immune response quicker?

A
  • Memory cells help the body to recognise the foreign cells so that the response is quicker and more effective (Larger)
  • The memory cells also increase the speed in which clonal expansion happens
  • This is so that the cells that are able to recognise the antigens are able to reproduce quicker to fight the pathogens
58
Q

What response does a vaccination aim to trigger?

A
  • A vaccination causes an immune response and it aims to trigger the second immune response
  • This is so that the person who is vaccinated can fight the pathogens quickly with the second (stronger) immune response
  • This leads to immunity
59
Q

What are the different types of immunity?

A
  • Natural
  • Artificial
  • Active (Actively producing the antibodies)
  • Passive (Antibodies are given/injected, not produced)
60
Q

What are some examples of the different types of immunity?

A
  • Natural active: Get sick then get immune from the sickness triggering a secondary immune response
  • Artificial active: Vaccination, allows people to actively produce the antibodies for themselves
  • Natural passive: Babies get antibodies from breast milk to protect them from specific viruses and pathogens that the mothers body already produces antibodies against
  • Artificial passive: Antitoxin injection, an injection of antibodies to neutralize some toxin to stop it from having its negative effects on the individual (Antivenom)
61
Q

What are the different strategies for vaccinating?

A
  • Ring immunity

- Herd immunity

Biology (23 decks)

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