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BIOLOGY MODULE 4 > 1 - COMMUNICABLE DISEASES > Flashcards

1 - COMMUNICABLE DISEASES Flashcards

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1
Q

What organisms cause disease?

A

Viruses, bacteria, fungi and protoctista - these are called pathogens.

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2
Q

VIRUSES

A
  • Size: 20-250nm
  • Invade cells and take over their genetic machinery by carrying their own DNA and RNA
  • Cause host cells to make copies of the invading virus
  • Cause host cells to burst, enabling the new viruses to invade healthy cells
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3
Q

BACTERIA

A
  • Size: 0.5-20um
  • Multiply rapidly in the host body
  • Damage cells and realease waste products and toxins
  • Cause the blackening and death of plant tissues by living in vascular tissues
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4
Q

FUNGI

A
  • Size: 10-100um
  • Send out filaments such as reproductive hyphae which grow to the surface of the skin to release spores
  • Form a mycelium under skin surface
  • Cause plant decay by realeasing extracellular enzuymes to digest surrounding tissue
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5
Q

PROTOCTISTA

A
  • Enter hosts and feed on contents as they grow

- Parasites such as Plasmodium have immature forms that feed on haemoglobin in RBCs

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6
Q

What are the two main mechanisms of disease?

A

Damaging cells and producing toxins

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7
Q

What are the 2 types of toxins and when are they produced?

A

1) Exotoxins - released by a living, normal pathogen

2) Endotoxins - released when the pathogen itself is damaged

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8
Q

What are some examples of plant diseases? What are they caused by?

A
  • Ring rot, caused by bacteria
  • Tobacco mosaic virus, caused by viruses
  • Black sigatoka in bananas, caused by fungi
  • Blight in tomatoes and potatoes, caused by protoctista
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9
Q

What are some examples of animal diseases? What are they caused by?

A
  • Caused by bacteria: Tuberculosis and Bacterila meningitis
  • Caused by viruses: HIV/AIDS and Influenza
  • Caused by fungi: Ringworm in cattle and Athlete’s fppt in humans
  • Caused by protoctista: Malaria
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10
Q

What are the 2 ways of the tramission of pathogens?

A

Direct and indirect transmission

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11
Q

Compare direct and indirect transmission.

A

Direct is the passing of a pathogen from host to new host with no intermediary, whereas indirect is the passing of a pathogen from host to new host via a vector

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12
Q

What are some passive physical defences of plants?

A
  • Cell wall:
    ~made of cellulose, making it a strong barrier
    ~lignin thickening, waterprrof and completely indigestible
  • Cuticles: waxy, prevetnting water from collecting on surfaces
  • Bark: acting as a strong barrier
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13
Q

What are some chemical defences of plants?

A
  • Ternepoids which are essential oils that create scents and have antibacterial and antifungal properties
  • Phenols which deactivate digestive enzymes of insects to prevent transmission of pathogens, also antibacterial and antifungal properties
  • Alkaloids which inhibit enzyme action and protein synthesis to reduce damage caused by pathogen invasion
  • Defensins which have broad antimicrobal activity, inhibting action of ion transport channels in pathogens
  • Hydrolytic enzymes which are found in spaces between cells and break down and degrade pathogens
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14
Q

What are some active plant defences?

A
  • Cell walls thicken and strengthen with additional cellulose .
  • Callose deposits between plant cell wall and cell membrane near pathogens to strengthen it
  • Oxidative bursts that produce highly reactive oxygen molecules capable of damaging cells of invading organisms
  • Closure of stomata with the help of gaurd cells when pathogens are detected
  • Tylose formation which blocks xylem vessels to prevent spread of pathogens
  • An increase in production of chemical defences
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15
Q

How many types of animal immune defences are there and how do they differ?

A

There are 3 types: primary defences, non-specific secondary defences, and specific secondary defences. Primary defences are non-specific mechanisms which prevent the entry of pathogenic organisms. Secondary defences are mechanisms carried out once the pathogen has invaded healthy body cells.

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16
Q

How does skin prevent pathogens from entering the body?

A
  • It is on the outer layer of the epidermis
  • Cells called keratinocytes dry out and die
  • Their cytoplasm becomes replaced with keratin - this process is called keratinisation
  • They act as a barrier to pathogens
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17
Q

How do blood clotting and wound repair work as primary defences?

A
  • Platelets release clotting factors that can cause an enzyme cascade that forms a clot
  • This eventually creates a scab under which skin is repaired
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18
Q

How do mucous membranes work as primary defences?

A
  • Protect surfaces which are at risk of infection
  • Cause goblet cells to release mucus
  • Found in epithelial linings of airways, digestive and reproductive systems
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19
Q

What are expulsive reflexes?

A

Examples are coughing and sneezing, which expel air that carries microorganisms. Another is example is vomiting which also releases any toxins and microoganisms in the stomach.

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20
Q

How does inflammation act as a primary defence?

A

Histamine is released when mast cells are injured. This causes vasodialation and more permeable capillary walls, which results in swelling, also called oedema.

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21
Q

How is the non-specific response carried out and what components are involved in this?

A

Ir is carried out by the process of phagocytoisis which involves 3 types of phagocytes: neutrophils, macrophages and monocytes as well as as antibody opsonin.

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22
Q

NEUTROPHILS

A
  • found in bone marrow
  • contain large amount of lysosomes
  • digest pathogens
  • die soon after, collecting in the infected area and forming pus
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23
Q

MACROPHAGES

A
  • found in tissues and lymph nodes
  • engulf pathogens without fully digesting them
  • initiate specific immune responses by prestened undigested antigens to lymphocytes
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24
Q

MONOCYTES

A
  • travel in the blood
  • quickly fight off pathogens
  • largest type of WBCs
25
Q

OPSONIN

A
  • binds to antigens non-specifically

- increase phagocyte’s ability to bind to and engulf inavding pathogens

26
Q

Describe phagocytosis.

A

After the pathogen is recognised, the phagocyte attaches to its receptors and enguls it by endocytosis, forming a phagosome. Then, lysosomes begin to fuse, releasing disgestive enzymes and forming a phagolysosome. Here, the pathogen is broken down and the products are released into the cytoplasm by exocytosis.

27
Q

What is the specific immune response? What cells are involved?

A

It targets 1 specific multiplying pathogen only. There several types of lymphocytes involved: T killer cells, T helper cells, B cells, T regulator cells and T memory cells.

28
Q

Where do lymphocytes come from and where do they mature?

A

They come from the bone marrow - B cells mature there whereas T cells mature in the thymus. Then they proceed to the lymph nodes and circulate through the lymphatic system.

29
Q

How is the specific immune response generally carried out?

A

(1) Clonal selection = when lymphocytes meet antigen-presenting cells (macrophages)
(2) Clonal expansion = when lymphocytes clone themselves and begin attacking pathogens
(3) Differentiation = when lymphocytes undergo different proccess after clearing up the invasion
(4) Shut down of response and establishment of immunity

30
Q

CLONAL EXPANSION

A

(1) T killer cells = multiply and attack and kill infected host celll
(2) B cells = multiply
(3) T helper cells = release interleukins which trigger B and T cells to mutiply

31
Q

DIFFERENTIATION

A

(1) T killer cells = some undergo apoptosis while others become memory
(2) B cells = some become plasma cells which manufacture antibodies that then attack infected cells and others become memory B cells
(3) T helper cells = some become more T helper cells and others become memory cells

32
Q

SHUT DOWN OF RESPONSE

A

T regulator end the immune response when the pathogen is successfully removed. Memory cells provide long-term immunity.

33
Q

What is cell signalling and why is it important?

A

Cell signalling is communication between cells using messenger molecules called cytokines/interleukins and it ensures that the body responds to infection quickly.

34
Q

What are autoimmune diseases?

A
  • diseases which arise when antibodies attack an organism’s own antigens
  • possibly due to exposure but causes are mostly unknown
  • prevented by T regulator cells
  • examples include: arthiritis is when antibodies attack membranes around the joint and lupus is when antibodies attack certain proteins in the nucleus of cells and affected tissues
35
Q

List the features and describe the structure of an antibody.

A
  • 2 pairs of polypeptide chains: light and heavy
    > connected and held together by disulfide bonds
  • Variable region: complementary to the shape of the antigen it targers
  • Hinge region: allows flexibility and enables the molecule to grip more than 1 antigen
  • Constant region: binds to the phagocytic cell, stimulating phagocytosis
36
Q

What are the proccesses of the 4 kinds of antibodies called?

A

Opsonisation, agglutination, neutralisation, and anti-toxinisation.

37
Q

OPSONISATION

A
  • can be part of specific and non-specific responses

- attaches to receptors on a pathogen thus disabling it from working

38
Q

AGGLUTINATION

A
  • binds to surface of pathogens, causing them to clump together
  • makes it easier for macrophages to recognise and destroy pathogens by phagocytosis
39
Q

NEUTRALISATION

A
  • binds to antigens on a pathogen’s membrane to prevent it from entering/attacking host cells
  • encourages macrophages to phagocytose the pathogen
  • neutralises pathogens by inactivating them
40
Q

ANTI-TOXINISATION

A
  • stem from neutralising antibodies

- binds to toxins released by pathogens, rendering them harmless

41
Q

What are vaccines?

A

They are injections that promote the developement of antibodies to give immunity.

42
Q

What is herd vaccination?

A

A vaccination programme where a high number of people are vaccinated at risk, making the disease less able to spread as they become immunated.

43
Q

What is ring vaccination?

A

A vaccination programme used when a new case of disease is reported, where all people in immediate vicinity of it are vaccinated. It is used in livestock disease worldwide.

44
Q

What are the 5 types of vaccines?

A

Attenuated, inactivated, subunit, toxoid, and whole live organisms.

45
Q

ATTENUATED

A

A live vaccine which has had its virulence reduced (e.g measles)

46
Q

INACTIVATED

A

A dead form of a pathogen (e.g polio vaccine)

47
Q

SUBUNIT

A

An injection of only antigens (e.g Hep B)

48
Q

TOXOID

A

A harmless version of a toxin (e.g tetanus)

49
Q

ORGANISM

A

A whole live organism of a similar less harmful organism (e.g cowpox for smallpox)

50
Q

What is a pademic?

A

It is when a disease can spread across multiple countries.

51
Q

What are the different types of immunity?

A

(1) Natural = achieved through normal life processes
(2) Artificial = provided through medical intervention
(3) Active = when the immune system is activated and antibodies are produced
> natural e.g. infection
> artificial e.g. vaccination
(4) Passive = when antibodies are provided from another source
> natural e.g. maternal antibodies from the placenta
> artificial e.g. monoclonal antibodies

52
Q

Why isn’t the passive artificial immunity long term?

A

Because memory cells are not produced

53
Q

Why do we need to develop new medicines?

A
  • new diseases are emerging
  • no effective treatment for existing diseases
  • certain patients are inable to take some treatments
  • antibiotic treatments are becoming less effective
54
Q

How can new medicines be discovered from plants?

A
  • unripe poppy seed-heads enabled the discovery of morphine and opium by their use as anaesthetic, reducing nervous action in central nervous system in the central nervous system so that no pain is felt
  • willow-bark was used to relieve pain and fever as well as to synthesise asparin and ibuprofen
55
Q

How can new medicines be discovered from microorganisms?

A

An accidental discovery where fungus called penicillium which demonstrated the potential value of antibiotics, by its release of compounds which kill bacteria, was purified.

56
Q

What are antibiotics used for?

A
  • to prevent the growth of fungi or bacteria

- to prevent the infections of wounds in WW2

57
Q

What are some causes of antibiotic resistance?

A
  • over-use and misuse of antibiotics
    > current antibiotics have limited effectivity as a result
  • bacteria have become imfamous for their multiple resistances to a range of antibiotics
58
Q

What are some problems caused by antibiotic resistance?

A

MRSA - it is common in hospitals causing life-threatening infection, where the bacteria S. aureus has become resistant to most antibiotics, including methicillin.

59
Q

What are some new approaches to medicine?

A
  • Personalisation: the hope of sequencing people’s genomes in order to create a personalised medicine based on their exact illness
  • Synthetic biology: developing new chemicals which were designed to mimic properties of natural biological systems

BIOLOGY MODULE 4 (1 decks)

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