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My AS level biology - OCR A > 4.1 - Communicable Diseases - New > Flashcards

4.1 - Communicable Diseases - New Flashcards

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1
Q

Pathogen def

A

A microorganism that causes disease

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2
Q

4 different types of pathogen

A

Bacteria
Fungi
Viris
Protoctista

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3
Q

Different bacterial diseases

A

TB
Bacterial Meningitis
Ring Rot (in plants)

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4
Q

Different diseases caused by viruses

A

HIV/AIDS
Influenza
Tobbaco Mosaic Virus

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5
Q

Different fungal diseases

A

Black Sigatoka
Ringworm (cattle)
Athlete’s foot (humans)

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6
Q

Diseases caused by protoctista

A

Blight (tomatoes and potatoes)

Malaria

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7
Q

Direct Transmission def

A

Passing a pathogen from host to new host, with no intermediary

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8
Q

Indirect Transmission

A

Passing a pathogen from host to new host, via a vector

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9
Q

Transmission def

A

Passing a pthogen from an infected individual, to an uninfected individual

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10
Q

Vector def

A

An organism that carries a pathogen from one host to another

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11
Q

Simple pathogen life cycle

A 
Travel from one host to another (transmission)
Enter host tissues
Reproduce in host tissues
Leave the host tissues
Infect a new uninfected person
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12
Q

Different means of direct transmission

A

Direct physical contact
Faecal-oral transmission
Droplet infection
Transmission by spores

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13
Q

Methods to decrease transmission by direct physical contact

A

Direct physical contact

  • hygiene - wash hands regularly
  • keep surfaces clean - especially door handles
  • clean and disinfect cuts and abrasions
  • sterilise surgical instruments
  • use condoms during sexual intercourse
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14
Q

Methods to decrease transmission by faecal-oral transmission

A
  • treatment of waste water and drinking water to decontaminate and reduce risk
  • thorough washing of all fresh food (using treated water)
  • careful prep and cooking of all food
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15
Q

Methods Methods to decrease transmission by droplet infection

A

Catch it - bin it - kill it
Cover mouth when coughimg or sneezing
Use tissue and dispose of correctly after use

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16
Q

Methods to decrease transmission by transmission by spores

A

Use of a face mask

Washing skin after contact with soil

17
Q

Social factors affecting transmission of diseases

A 
Overcrowding
Poor ventilation
Poor health - especially with HIV/AIDS
Homelessness
Living or working with people who ahve migrated from areas where disease is common
18
Q

Life cycle of Plasmodium and malaria

A 
Person with malaria
Gametes of Plasmodium in blood
Female Anopheles mosquito sucks blood
Plasmodium develops and migrates to mosquito’s salivary glands
Uninfected person is bitten
Plasmodium migrates to liver
Plasmodium migrates to blood
19
Q

What conditions are optimal for many pathogens

A

Warm, moist conditions

  • allows them to reproduce more rapidly
  • so greater variety of pathogens may be present in these conditions
20
Q

Callose def

A

A large polysaccharide deposit that blocks old phloem sieve tubes

21
Q

Plant physical defences, and more info on the,

A
  • Cellulose cell wall - contains many chemical defences that can be activated on detecting pathogen
  • Lignin thickening of cell walls - waterproof and almost completely indigestible
  • Waxy cuticles - prevent water colection on cell surfaces, prevents pathogens accumulating there, need water to survive
  • Bark - contains a variety of chemical defences against pathogens
  • Stomatal closure - closed, as are possible points of entry for pathogens - controlled by guard cells when pathigens detected.
  • Callose - large polysaccharide deposited in sieve tube at end of growing season.
  • blocks flow of assimlates, and pathogens in sieve tube elements
  • Tylose Formation - balloon-like swelling or projection that fills the xylem vessel
  • plugs vessel, and water (and pathogens) can longer move through the xylem
22
Q

Chemical defences for plants

A 
Terpenoids
Phenols
Alkaloids
Defensive proteins
Hydrolytic enzymes
23
Q

Active defences in plants, and more info

A
  • Cell walls become thickened with additional cellulose
  • Deposition of callose between plant cell wall and memebrabe near invading pathogen
  • Oxidative bursts - produce highly reactive O2 molecules capable of damaging invading pathogen cells
  • Increase in production of chemicals
  • Canker - necrotic lesionin woody tissue - causes death of cambium tissue in bark
24
Q

Inflammation def

A

swelling (odoema) and redness caused by infection

25
Q

what is a mucous membrane?

A

specialiswd epithelial tissue covered by mucus

26
Q

primary defences def

A

defences that prevent pahogens entering the body

27
Q

list different primary defences in the human body

A 
skin
blood clotting and skin repair
mucous membranes
coughing and sneezing
inflammation

Other:
enzymes and antibodies in tear fluid
ear canal lined by wax - traps pathogens
mucus plug in cervix, relatively acidic conditions in vagina

28
Q

what are the primary “non-specific” defences

A

defences that prevent pathogens entering the body and bloodstream, but are not specific to any one pathogen or antigen - prevent entry of any pathogen

29
Q

how does skin act as primary defence

A

skin conists of layers of cells
outer layer called epidermis
acts as a barrier for pathogens

30
Q

Outline the process of blood clotting and skin repair

A

Blood Clotting

platelets bind to exposed collagen
they release clotting factors
this activates an enzyme cascade
this causes fibrinogens to form insoluble fibres that attach to the platelets in the plug
red blood cells and platelets are trapped in place
this forms a blood clot

Skin Repair

when clot has formed
dries out and forms a scab
as it dries, it draws sides of the cut together
makes temp. seal under which skin is repaired
fibrous collagen deposited under scab
stem cells in epidermis divide by mitosis to form new skin cells
they migrate to edge of cut - diff. to form new skin
new blood vessels grow to supply O2 and nutrients to new cells
edge of cut contracts and skin is repaired - scab falls off

31
Q

how does mucous membrane act as primary defence

A

thin layers in body, e.g. alveoli, lungs, blood vessels etc., contain mucous membranes
mucus secreted by goblet cells
mucus traps any pathogens
epithelium also contains ciliated cells
cilia can move to waft the mucus with pathogens along and out of airways
enter oesophagus and is swallowed
killed by stomach acid

32
Q

how coughing and sneezing acts as primary defence

A

expulsive reflex

expels any pathogens in airway that caused the irritation

33
Q

inflammation mechanism

A

pathogen detected by mast cells
this causes release of histamines
causes vasodilation
makes capillary walls more permeable to white blood cells
plasma and WBC leave blood vessel and enter tissue fluid
causes increased prod. of tissue fluid
causes swelling (odoema)
excess tissue fluid drained into lymphatic system - where lymphocytes are stored
can lead to pathogens coming into contact with lymphocytes
causes initiation of primary immune response

34
Q

what is an antigen presenting cell (APC)?

A

a cell (usually phagocyte) that incorporates the antigens of a pathogen into its cell surface membrane so it can be recognised by other cells in immune system

35
Q

clonal selection def

A

selection of a specific B or T cell specific to the antigen

36
Q

what are cytokines?

A

hormone-like molecules used in cell signalling to stimulate the immune response

37
Q

what are neutrophils?

A

a type of white blood cell that engulfs foreign matter and traps it in a large vacuole (phagosome),
which fuses with lysosomes to digest the foreign matter.
- a type of phagocyte

38
Q

what are opsonins?

A

proteins that bind to the antigen on a pathogen and then allow phagocytes to b

39
Q

parasite def

A

an organism that:

  • lives in/on host
  • gains nutrition from host
  • at expense of host

My AS level biology - OCR A (19 decks)

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