b3 infection and response Flashcards
what are pathogens?
microorganisms that cause infectious disease in animals and plants
what do they rely on to grow?
their host’s nutrients and conditions
what are the four types of pathogens?
bacteria, fungus, virus and protist
what are communicable diseases?
diseases that can spread fro organism to organism
how do bacteria cause damage?
divide rapidly via binary fission
they then produce toxins damage the cells and tissue
methods that the body counterattacks invading pathogens
1) phagocytosis
2) production of antibodies
3) production of antitoxins
what is phagocytosis?
when the white blood cell engulfs the invading pathogen and digest them
what is the production of antibodies?
when the white blood cells start to produce proteins (called antibodies), which lock onto the invading pathogen, then can be found by another WBC and destroyed
what feature of the antibodies makes it so that they dont lock onto anything other than the desired pathogen?
they are specific to the antigen on the pathogen
what causes immunity?
after the WBC have produced the specific antibodies for the pathogen, if this same pathogen type re-enters, the antibodies will be made more rapidly, destroying the pathogen
what does the production of antibodies rely on?
the detection of unknown/ unfamiliar antigen
what is the production of antitoxins?
when pathogens produce toxins, the WBC produce antibodies to neutralise them
how do viruses cause harm to the body?
they break the cell wall and invade it
they then use the structures inside the cell to reproduce, which damages the cell until it bursts,
this could cause cancer
how do protist cause harm?
they are insects or bugs that spread disease from one organism to another
how do fungi cause harm?
invade tissue and disrupt their function to reproduce, taking nutrients from the host
how can pathogens spread via air?
1) droplets containing pathogens fly into the air when people sneeze or cough and can get breathed in by others
2) some fungal spores can float through the air and land on something they can infect
how can pathogens spread via contact?
microbes can be passed by skin-to-skin contact with an infected person, or when handelling something that an infected person has touched
how can pathogens be spread via water?
water can contain harmful microbes if not treated with chlorine or boiled. microbes can get in the body when water is swallowed
how can pathogens be spread via food?
food can have harmful microbes in them, microbes can get in the body when food swallowed, causing food poisoning
what are the body’s defence mechanisms?
1) the skin serves a protective barrier and secretes antimicrobial substances
2) the hairs and mucus in the nose trap particles which may contain pathogens
3) the trachea and bronchi secretes mucus to trap pathogens. and lined with cilia which waft up mucus to the back of the throat where it can be swallowed
4) the stomach produces hydrochloric acid which kills pathogens
5) the tears in eyes contain enzymes which kill pathogens. plus eyelashes
what are examples of viral diseases?
measles
HIV
tobacco mosaic virus
what is measles? symptoms? how is it spread?
1) viral disease
SYMPTOMS: red skin rash and symptoms of a fever
SPREAD BY: droplets from an infected person’s sneeze or cough
how can measles be prevented?
vaccinations
what is HIV? symptoms? how is it spread?
1) virus disease
SYMPTOMS: flu-like symptoms for a few weeks and muscle and joint pain
SPREAD BY: sexual contact or by exchanging bodily fluids eg blood
how can HIV be treated/ controlled?
1) it can be controlled by giving the patient antiretroviral drugs to stop the virus from replicating
effects of HIV with other diseases?
can weaken the immune system so badly that it cant cope with other infections or cancers. atp it is known as AIDS
what is tobacco mosaic disease? symptoms? how is it spread?
1) viral disease
SYMPTOMS: discolouration in leaves and mosaic pattern which affects growth
SPREAD BY: contact, eg workers hands
what are examples of bacterial diseases?
salmonella
gonorrhoea
what is salmonella infection? symptoms? how is it spread?
1) bacterial disease that causes food poisoning
SYMPTOMS: fever, stomach cramps, vomiting and diarrhoea
SPREAD BY: eating food which is contaminated with salmonella bacteria eg eating chicken that has the disease when it was alive
what is gonorrhoea? symptoms? how is it spread?
1) sexually transmitted bacterial disease
SYMPTOMS: pain during urination, thick yellow/green discharge from the vagina or penis
SPREAD BY: sexual contact eg unprotected sex