12.1 Diseases Flashcards
(54 cards)
What is the definition of disease?
Any deviation from the normal structure or function of a body part or even organ, characterised by a set of symptoms.
What is a parasite?
Organisms that live in or on another organism (the host).
What is a pathogen and give examples
Pathogens are organisms that cause disease
-Virus
_Protist
- fungi
-Bacteria
What are the key points about the pathogen: bacteria?
Cells are smaller than ours
Reproduce rapidly
Damage cells and release toxins
Examples include TB and cholera
What are the key points about the pathogen: fungi?
Fungus lives on the skin and sends out haephe grow on the surface and to release spores
Causes redness and irritation
Examples include athletes foot in humans
What are the key points about the pathogen: virus?
Viruses invade cells and take over genetic and other organelles, causing the cell to make copies of the virus.
The cell then bursts releasing the virus.
Examples include coronavirus, HIV and in plants tobacco mosaic virus
What are the key points about the puthogen : protists?
Cause harm by entering the hosts cell and feeding on the contents whilst they grow
Examples include malaria ( plasmodesmodium has immature forms that feed on red blood cells)
Malaria knowledge
Spread by mosquitos need warm climate, and spread through bites
Caused by the protist plasmodia
Effects all ages of red blood cells
Currently no cure e.g. Vaccine, just prevention
HIV and aid’s knowledge
-Infects helper t-cells causing in deficiency the immune system, has the ability to put it genes into hosts cells
- HIV starts with little to no symptoms and normal t-cells, the next stage the t-cell count lowers and eventually t-cells reduce and it turns to UIDs with symptoms
- there is no cure or vaccine but there are suppressants.
Plant diseases transmission and defence: black Sigatoka
- A banana disease, fungus caused attacks leaves and digests them
- spread directly and indirectly
- resistant strains are being developed but there is no cure
Plant diseases transmission and defence: potato blight
- Caused by a fungus, penetrating host cells and destroying
-Spread directly and indirectly - no cure but resistant strains, good management, and chemical treatments
Plant diseases transmission and defence: tobacco mosaic virus
- A virus that affects tobacco and many other plants, damages leaves and flowers stunting growth reducing yield
-Transfered direct and indirectly - no cure but resistant strains
Plant diseases transmission and defence: ring rot
- Bacterial disease of tomatoes and potato, damaging leaves and destroys crops
-Transfered directly and indirectly - there is no cure, once a field is infected nothing can the grown for 2 years
Explain direct and indirect transmission in plants
Direct transmission, contact directly of a a deathly plant with a diseased plant
Indirect transmission, soil contamination, infected plants leaving pathogens behind, or spores effecting next crop
Not on the spec but helpful:
Ash dieback and Dutch elm disease
Ash die back is a fungus, damaging ash treas transported by spores
Dutch elm disease is a fungus transferred by a beetle blocking the xylem
Factor affecting transmission in plants
→ o.vercrowding
→ luck of minerals
→ damp and warm conditions
→ poor control of imports
→ climate change.
→ bad farming, unclean machinery
How do plants protect against diseases?
Waxy cuticles on leaves
Callus formation
Bark on tress
Strengthen cell walls.’
Chemically eg caffeine or citronella
What are some vectors of diseases?
- Wind
- water
-Animals
-Humans
Describe the human defence of blood clotting?
1) palates are activated by the damaged tissue, serotonin allows smooth muscle to contract, causing vasoconstriction and narrowing blood vessel
2) thromboplastin catalyses prothrombin to thrombin
3) thrombin catalyses fibrinogen and fibrin is formed causing the blood to clot.
What are the 4 non specific human defences to disease
→ barriers e.g.skin
→ blood clothing
→ inflammation
→ phagocytosis
How does inflammation work?
1) damaged or infected cells release histamines, which attracts neutrophils to the area
2) makes capillaries become leaky which allows more tissue fluid to escape, causing lymphocytes to be delivered to the area, causing swelling
3) excess lymph is drained back into the lymphatic system
What are opsonins and their role in defence?
Complimentary proteins, that tag pathogens so they candy easily recognised by phagocytes which have receptors to detect and bind to opposing for engulfing
Describe the process of phagocytosis?
1) the phagocyte recognises the foreign antigen and moves towards it (chemotaxis) due to chemicals released
2) cell surface membrane invaginates and pathogen engulfed in a vesicle called a phagosome
3) lysomes move and fuse with phagosome to make a phagolysome
4) hydrolytic enzymes digest cell
How do macrophages work as part of phagocytosis (antigen presenting cells)
Takes the antigen from the pathogen
Combines it with glycoproteins
Moves antigen to the cell surface membrane
