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A-Level Biology > M3 C12 Communicable diseases > Flashcards

M3 C12 Communicable diseases Flashcards

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1
Q

what are the 4 different types of pathogens

A
  1. virus
  2. fungi
  3. bacteria
  4. protoctista
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2
Q

what is a pathogen

A

a disease causing organism

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3
Q

define communicable disease

A

a disease caused by pathogen that can be transmitted

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4
Q

what are the features of bacteria [5]

A
  • prokaryotic
  • reproduce rapidly
  • damage cells
  • can release toxins which are toxic to host
  • can be killed w/ antibiotics
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5
Q

what are the defining features of fungi [5]

A
  • eukaryotic
  • most are multicellular (exp. yeast)
  • digestion is extracellular
  • SAPROPHYTIC (feed on dead tissue) or PARASITIC (living tissue… parasitic are pathogenic
  • reproduce by producing spore
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6
Q

describe the features of viruses [5]

A
  • non-living
  • very small
  • genetic material inserted into host cell, hijacks hosts’ biochemistry
  • all natural viruses are pathogenic & can cause disease in any other type of organism incl. bacteria
  • some viruses modified to treat disease by killing pathogen
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7
Q

describe the features of protoctistsa [5]

A
  • eukaryotic
  • varied, organisms which dont fit into other groups
  • small number are pathogenic in plants and animals
  • the protists causing disease are parasitic
  • often need a vector to transfer from one individual to another
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8
Q

what are the two modes of action of a pathogen on a host

A
  • DIRECT DAMAGE OF TISSUE, viruses & protists damage cells as they burst to release new pathogens, protists use cell contents during reproductions.
  • PRODUCTION OF TOXINS, leading to damage of tissues (most bacteria & some fungi, the toxins are a by-product of their metabolism)
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9
Q

what is meant by the term transmission

A
  • the way in a which a parasitic microorganism travels from one host to another
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10
Q

what are the 3 ways of direct transmission affecting animals

A
  • direct contact: contagious diseases eg. Athletes foot. Kissing and exchange of bodily fluids eg. STD
  • inoculation: Breaks in the skin/animal bite/puncture wound/ sharing needles
  • ingestion: taking in contaminated food/drink
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11
Q

what are the 3 ways of indirect transmission

A
  • fomites: inanimate objects
  • droplet infections: droplets of saliva
  • vectors: transmit pathogens from one host to another (water can be a vector, malaria via mosquito)
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12
Q

What are the factors affecting the transmission of pathogens which can lead to animal diseases?

A
  • environmental: overcrowding/ living & working conditions
  • poor nutrition
  • compromised immune system
  • poor disposal of waste, breeding site for vectors
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13
Q

describe macrophages

A
  • larger cells
  • longer lived
  • made in bone marrow
  • travel as monocytes until settled in tissues to become macrophages
  • found in lymph nodes/ alveolar walls/liver
  • often are APCs
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14
Q

What is meant by a passing defence

A
  • Present before pathogen entry

- barriers to entry of pathogens

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15
Q

Describe the passive physical defences of a plant

A

LIGNIN- waterproof, almost completely indigestible

WAXY CUTICLE- prevent water collecting on cell surface

CELLULOSE CELL WALLS- physical barrier, contains variety of chemical defences which are activated in presence of pathogen

BARK- contains chemicals that work against pathogens

STOMATA-closure, stomata are possible entry points for

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16
Q

outline the active defences induced in a plant response to being invaded by a pathogen

A
  • deposition of callose between plant cell wall & membrane, strengthens cell wall & blocks plasmodesmata
  • bursts of highly reactive oxygen molecules capable of damaging pathogens
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17
Q

what are/what do cytokines do

A
  • cell signalling molecules that inform other phagocytes that body is under attack
  • stimulates others to move to site of infection
  • can increase body temp. & stimulate specific immune responses
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18
Q

explain canker

A

a sunken necrotic lesion in the woody tissue such as the main stem or branch. It causes death of the cambium tissue in the park

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19
Q

what are the non-specific/ primary defences of animals

A
  • SKIN, physical barrier which prevents entry of pathogen. cells of the epidermis dry out as they migrate to surface of the skin. Lower pH. makes a hostile place for bacteria
  • LYSOZYMES, in tears & urine. kills pathogens & prevents infection
  • EXPULSIVE REFLEXES, coughing/sneezing ejects pathogen from respiratory system. diarrhoea
  • MUCUS MEMBRANES, line internal cavities exposed to the external air, contain goblet cells (produce mucus) and cilliated epithelial ( (waft mucus)
    - lungs are warm and moist :. +hospitable for
    pathogens
  • STOMACH ACID: kill pathogens, secreted by stomach lining cells
  • EAR WAX: natural barrier to dirt & pathogens. prevent entry into inner ear
  • FEMALE REPRODUCTIVE SYSTEM: cervix-mucus plug, barrier. vagina-relatively acidic environment
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20
Q

what is involved in the formation of a blood clot

A
  • clotting factors
  • platelets
  • cell signalling molecules
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21
Q

how do wounds repair

A
  • the clot dries out, forming a hard tough scab. keeping out pathogens.
  • new epidermal cells grow underneath
  • blood vessels regenerate
  • collagen fibres are deposited to strengthen the new tissue
  • scab
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22
Q

describe neutrophils

A
  • common
  • lobed nucleus
  • released in large numbers
  • large lysosomes
  • dead neutrophils can collect and form pus
  • short lived, die after ingesting bacteria
  • frequently leave blood stream to patrol tissues for foreign bodies
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23
Q

describe macrophages

A
  • larger cells
  • longer lived
  • made in bone marrow
  • travel as monocytes until settled in tissues to become macrophages
24
Q

what is an APC

A

an antigen presenting cell, they are macrophages that display antigens from a partially digested pathogen. the antigen is moved to special protein complex on plasma membrane

25
Q

what is the role of APCs

A

travel around the body & activate specific immune system responses

26
Q

which chemicals are involved in phagocytosis

A
  • cytokines

- opsonins

27
Q

what do cytokines do

A
  • cell signalling moleculesthat inform other phagocytes that body is under attack
  • stimulates others to move to site of infection
  • can increase body temp. & stimulate specific immune responses
28
Q

what are and what do opsonins do

A
  • chemicals that bind to pathogens
  • make pathogens more visable to phagocytes
  • phagocytes have receptors which bind to opsonins
  • immunoglobulins are strong opsonins
29
Q

what do T killer cells do

A

bind to cells presenting complimentary antigen & release toxins into infected cells, killing them

30
Q

what do T helper cells do

A

release interleukins which activate B cellls

31
Q

what do T regulator cells do

A

suppress the immune response

32
Q

what do T memory cells do

A

remain in bloodstream in case of reinfection

33
Q

cells that remain in the blood for a long time, providing long term immunity

A

memory cells

34
Q

a specific protein released by plasma cells that can attach to pathogenic cells

A

what is an antibody

35
Q

describe the characteristics of artificial passive immunity

A
  • immunity provided by injection of antibodies made by another individual eg. rabies
36
Q

signalling molecules that are used to communicate between different white blood cells

A

interleukins

37
Q

derived from B lymphocytes, cells that manufacture antibodies

A

plasma cells

38
Q

cells that release signalling molecules to stimulate the immune response

A

T helper cells

39
Q

cells that attack and destroy our own body cells that are infected by a pathogen

A

t killer cells

40
Q

cells that are involved with inhibiting or ending the immune response

A

t regulator cells

41
Q

what are the 4 types of immunity

A
  • natural active
  • natural passive
  • artificial active
  • artificial passive
42
Q

describe the characteristics of natural active immunity

A
  • immunity provided by antibodies made in the immune system as a result of infection
43
Q

describe the characteristics of natural passive immunity

A
  • antibodies provided via the placenta/ breast milk
44
Q

describe the characteristics of artificial active immunity

A
  • immunity provided by antibodies made in the immune system as a result of vaccination
45
Q

when does an epidemic occur

A
  • when a communicable disease spreads rapidly to a lot of people at local or national level
46
Q

when does a pandemic occur

A
  • when the same disease spreads across countries and continents
47
Q

what is herd immunity

A

when a significant number of people in the population have been vaccinated, giving protection to those w/o immunity (eg. elderly, babies etc. at high risk)

48
Q

what is cell signalling

A

communication between cells

49
Q

what are neutrophils

A

a type of phagocyte

50
Q

what are opsonins

A

a molecule that binds to surface of pathogens making it easier for phagocyte/neutrophils to engulf them

51
Q

what is a phagosome

A

the term for phagocytic vacuoles

52
Q

what are cytokines

A

cell signalling proteins released by WBC’s that help coordinate the immune response

53
Q

what are interleukins

A

a type of cytokine eg. T-helper cell releases interleukins which binds to a specific receptor on a B-lymphocyte and activates it

54
Q

what are agglutinins

A

a type of antibody that glues/sticks antigens together, phagocytes can destroy many pathogens at once

55
Q

what are antitoxins

A

a type of antibody that counteracts a toxin

A-Level Biology (11 decks)

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