4.1.1 Communicable Diseases Flashcards
Bacteria (pathogen)
Prokaryotes Shapes: • bacilli (rod) • cocci (sphere) • vibrios (comma shape) • spirilla (spiral) • spirochaetes (corkscrew shape)
Cell walls:
• Gram positive bacteria (purple/blue stain)
• Gram negative bacteria (red stain)
Viruses
Non-living
Invade living cells, host cell
Protoctista (Protista)
Eukaryotic
Wide variety of feeding methods
Use animals as host
May need a vector
Fungi
Eukaryotic
Multicellular
Digest food exracellularly before absorbing nutrients
Saprophytes - feed on dead/decaying matter
Produce spores which can spread
Pathogens; damaging host directly
- viruses take over cell metabolism
* fungi digest living cells and destroy them
Pathogens; producing toxins to damage host tissues
- most bacteria, toxins may break down cell membranes
* some fungi
Plant diseases; ring rot
Bacterial
No cure
Plant diseases; tobacco mosaic virus
Virus
No cure but resistant crop strains are available
Plant diseases; potato blight
Fungus
Host cells
No cure but resistant strains, management and chemicals used to reduce risk
Plant diseases; black Sigatoka
Fungus
No cure
Resistant strains being developed
Fungicides
Animal diseases; tuberculosis
Bacterial
Destroys lung tissue
Suppresses immune system
Animal diseases; bacterial meningitis
Bacterial
Infection of meninges of brain
Antibiotics will cure is early
Vaccines
Animal diseases; HIV/AIDS
Virus
Destroys immune system
Animal diseases; influenza
Viral
Kills ciliated epithelial cells
Flu vaccine
No cure
Animal diseases; malaria
Protoctista Mosquitos No vaccine Limited cures Control vectors
Animal diseases; ring worm
Fungal
Antifungal creams
Animal diseases; athlete’s foot
Fungal
Antifungal creams
Direct transmission in animals
- direct contact
- inoculation (break in skin)
- ingestion
Indirect transmission in animals
- fomites (bedding,socks)
- droplet infection / inhalation
- vectors
Factors affecting transmission of communicable diseases in animals
- overcrowding
- poor nutrition
- HIV
- climate change
- culture and infrastructure
- socioeconomic factors
Direct transmission in plants
Contact of healthy plant w diseases plant
Indirect transmission in plants
- soil contamination
* vectors (wind,water,animals)
Factors affecting the transmission of communicable diseases in plants
- over crowding
- poor mineral nutrition
- damp, warm
- climate change
Plant defended against pathogens; recognising an attack
Receptors respond to molecules
Defensive chemicals give alarm to other cells before they’re attacked
Plant defended against pathogens; physical defences
Produce high levels of callose - act as barrier to pathogens entering
Plant defended against pathogens; chemical defences
- insect repellant
- insecticides
- antibiotics
- antifungal compounds
Animals; non-specific defences — Keelung pathogens out
- skin
- mucous membranes
- lysozymes in tears and urine
Blood clotting and repair
• thromboplastin
• serotonin
Inflammatory response
• mast cells activated, release histamines and cytokines
• histamines make blood vessels dilate, more leaky
• cytokines attract white blood cells
Animals; non-specific defences — Getting rid of pathogens
- fevers - high temp inhibits pathogen production
* phagocytosis - wbc engulf and destroy pathogens (neutrophils/macrophages)
The stages of phagocytosis
1) pathogens produce chemicals that attract phagocytes
2) recognise non-human proteins
3) phagocyte engulfs pathogen, eclipsed in vacuole called phagosome
4) phagosome combines w lysosomes forming a phagolysosome
5) enzymes from lysosome digest and destroy pathogen
Helpful chemicals
Cytokines - cell signalling molecules, can stimulate specific immune system
Opsonins - ‘tag’ pathogens so their easily recognised
Animals; specific immune system — antibodies
Y shape = immunoglobulins
Form antigen-antibody complex
Hinge region provides flexibility to bind to two separate antigens
How antibodies defend the body
1) acts as oosonin, easily engulfed and digested
2) can’t invade once attached to antibody
3) a.b act as agglutinins cause complex’s to clump together - prevent spread, easily engulf
4) act as anti-toxins by binding to toxins
Animals; specific immune system — Lymphocytes and the immune response
B lymphocytes - Bone marrow
T lymphocytes - Thymus gland
•T helper - bind to surface antigens, produce interleukins that stimulate activity of B cells
•T killer - produce perforin to destroy pathogen by making holes in cell membrane
•T memory - part of immunological memory
•T regulator - suppress immune system to control and regulate it
•B Plasma cells - produce antibodies
•B effector cells - divide to form the plasma cell clones
•B memory cells - immunological memory, remember specific antigen
Animals; specific immune system — Cell mediated immunity
T lymphocytes respond to cells that have been changed in some way
1) phagocytosis
2) receptors of some T helper fit the antigens. These become activated and produce interleukins which stimulates more T cells to divide
3) clones T cells may develop into memory, produce interleukins, or stimulate development of clone T killer cells
4) cloned plasma cells produce a.b to bind to pathogen = primary immune response
