Disease and immune system Flashcards
What is a pathogen?
- Is an organism that causes disease
What are the types of pathogens ?
- Bacteria
- Virus
- Fungus
- Protocist
Explain Bacteria
- Prokaryote
- produce toxins - chemicals that interfere with enzyme reaction causes lack of certain proteins
- Tubercolosis - example of animal bacteria causes respiratory issues (lung tissue)
- Ringrot - plant damage in tomatoes, fruit potatoes and tomato , targets leaf so photosynthesis is unable to take place
Explain fungi
- spread by making spores
- can also produce toxins
- saprophytic organisms so can digest and feed on dead organisms
- animal disease : Athletes foot
- plant disease - black sigatoka - destroys the leaves causing black lines on the leaves
Explain Virus
- Hijack cells to reproduce
- Inject genetic material into host cell
- Genetic material combines with host cell DNA
- Viral DNA/RNA and proteins are made using the host cells’ resources and mechanisms
- animal disease - AIDS - target t-helper cells
-plant disease - Tobbaco mosaic virus - discolouration (losing chlorophyll) saic pattern on leaves
Explain Protist
- animal disease, malaria through vector (mosquitoes)
transferred from the mosquito into the bloodstream reproduces into cells - plant disease - potato blight -
What is direct transmission ?
Disease directly transmitted from one organism to another e.g droplet infection , sexual intercourse or touching an infected organism
- Inoculation - blood transfusion, sharing needles, Ingestion (contamination through food)
What is indirect transmission ?
- transmitted via an intermediate (air, water food, organism or another organism (vector)
- Fomites: using or touching contaminated things
How does transmission happen in plants ?
- Direct contact
- Vectors
- Contamination of soil
What are the factors that affect transmission ?
- Hygiene
- Weak immunity
Overcrowding: easy for pathogen to be transmitted
Genetic variation; natural susceptibility
WEBISM
What are the main non-specific defences?
- Skin
- Mucous membranes
- Blood clotting
-Inflammation - Wound repair
Expulsive reflexes
How does the skin protect against pathogens ?
Acts as a barrier , also as a chemical barrier, by producing antimicrobial and can lower PH inhibiting growth of pathogens.
How do mucous membranes protect against pathogens ?
- Secrete mucus, a sticky substance that traps pathogens and contains antimicrobial substances
Explain blood clotting
- A mesh of proteins that clots plug wounds to prevent pathogen entry and blood loss. They are formed by series of chemical reactions that take place when platlets are exposed by blood vessels.
Explain inflammation
-Inflammation is the body’s local response to infection and tissue damage, characterized by swelling, warmth, and pain around a wound.#
-Mast cells release histamine in response to tissue damage, leading to vasodilation and “leaky” capillaries, which allow fluid and plasma proteins to enter the tissues, causing swelling.
Explain wound repair
- A scab is formed as a result of blood clotting
Underneath this scab, there are stem cells that divide by mitosis to heal the wound
Wound healing occurs in a number of overlapping stages:
New blood vessels form
Collagen is produced
Granulation tissue forms to fill the wound
Stem cells move over the new tissue and divide to produce epithelial cells
Contractile cells cause wound contraction
Unwanted cells die