Communicable diseases Flashcards Preview

Paper 2 Biological diversity > Communicable diseases > Flashcards

Flashcards in Communicable diseases Deck (25)
Loading flashcards...
1

Disease definition

Condition that affects the normal functioning of an organism

2

Types of pathogens

Bacteria
Viruses
Fungi
Protoctists

3

Classification of bacteria

- Shapes (bacillus, coccus, vibrio)
- Cell walls (gram positive and gram negative)

4

Bacterial diseases

Ring rot
Bacterial meningitis
TB

5

Viral diseases

AIDS
Influenza
Tobacco mosaic virus (TMV)

6

Fungal diseases

Black sigatoka
Ringworm
Athlete's foot

7

Protictist diseases

Potato blight
Malaria

8

Viruses mode of damaging host tissue

- they affect the cell metabolism
- viral genetic material enters the host DNA
- virus uses the new cell to replicate new viruses which then burst out of the cell and destroying it
- spread out to infect neighbouring cells

9

Protoctista mode of damaging host tissue

- break cells but don't take over the genetic material
- digest and use the cell contents to reproduce

10

Fungi mode of damaging host tissue

- digest living cells and destroy them
- produce toxins which affect the cell

11

Bacteria mode of damaging host tissue

- produce toxins that damage and poison the cell
- toxins can damage the cell membrane, inactivate enzymes, interfere with host's genetic material

12

Types of transmission

Direct and indirect

13

Indirect transmission (animals)

- fomites (inanimate objects such as bedding, socks, cosmetic brushes)
- droplet infection (saliva or mucus)
- vectors (such as flies, water)

14

Direct transmission (animals)

- direct contact (kissing, body fluids contact, skin to skin contact, microorganisms from faeces)
- ingestion (through food or drink)
- inoculation (break in the skin, puncture wound, needles, animal bite)

15

Indirect transmission (plants)

- soil contamination
- vectors (wind, water, animals, humans)

16

Direct transmission (plants)

direct contact of a healthy plant with a diseased plant

17

Factors affecting communicable diseases (animals)

- overcrowding
- poor nutrition
- compromised immune system
- climate change
- culture and infrastructure

18

Factors affecting communicable diseases (plants)

- planting species susceptible to disease
- poor mineral nutrition
- poor water availability
- damp, warm conditions increase spread of disease
- climate change

19

Plant defences against pathogens

- physical
- chemical

20

Mechanism of recognition of attack in plants neurons

- Pathogenic enzymes break down cell membrane and the products are recognised by the receptors of the cell
- Signalling molecules alert nucleus to attack
- Polysaccharides (callose and lignin) are produced to strengthen the cell walls
- Defensive chemicals signal the other cells before they are attacked
- Some defensive molecules attack the pathogen directly

21

Physical defences

- Callose is synthesised and deposited b/n cell walls in order to prevent the pathogens from entering the neighbouring cells
- lignin and callose are deposited to form a barrier against infection
- callose deposits between sieve plates

22

Chemical defences

- insect repellents
- insecticides (pyrethrins)
- antibacterial compounds including antibiotics (phenols, defensives, lysosomes)
- antifungal compounds (phenols, caffeine, saponins, chitanases)
- general toxins (chemicals can be broken down to form cyanide compounds which are toxic)
- anti-oomycetes (glucanases)

23

Non-specific animal defences against pathogens

- skin (skin flora with with healthy microorganisms)
- mucus membrane lining on airways and body tracts
- lysozyme in tears and urine and acid in stomach
- repulsive reflexes such as coughing, sneezing, vomiting, and diarrhoea
- blood clotting and wound repair
- inflammatory responses
- fever
- phagocytosis

24

Inflammatory response

Mast cells are activated in damaged tissue and release chemicals:
- histamines make blood vessels dilate, causing redness and they become more leaky, so blood plasma is forced out and forms tissue fluid, causing swelling and pain
- cytokines attract white blood cells (phagocytes) to the site so they can undergo phagocytosis

25

Blood clotting

- Damaged tissue leads to platelets being activated, which release THROMBOPLASTIN
- THROMBOPLASTIN + CA2+ ions catalyse the formation of THROMBIN from PROTHROMBIN
- THROMBIN catalyses the production of FIBRIN from fibrinogen
- Fribrin + collagen fibres forms a mesh to forms a blood clot