B12 infection and response

• Diseases caused by pathogens are called communicable diseases
• transmission can occur through direct contact, water, air, unhygenic food preparation and vectors
• A pathogen is a micro-organism that causes a disease
• Bacteria are microscophic organisms that come in many shapes and sizes
• bacteria may produce toxins that damage tissues and make us feel ill
• viruses are many times smaller than bacteria
• viruses are genetic material inside a protective protein coat
• viruses have a high mutation rate and can only replicate inside host cells
• diseases are caused by viruses, fungi, bacteria and protists
• if a pathogen enters the body the immune system tries to destroy it
• white blood cells try to defend your body by phagocytosis (non-specific)
• white blood cells help defend your body by producing anti-toxins and anti-bodies (specific)
• tears contain enzymes that destroy micro-organisms
• your stomach contains hydrochloric acid that kills pathogens
• the trachea and bronchi secrete mucus that traps pathogens and then cilia waft it to the back of your throat where it is swallowed
• pathogens have too much competition in your intestines so they can't survive
• platelets clot blood to stop pathogens getting in
• your skin is dead skin cells and acts as a barrier for pathogens as they can't multiply on dead cells
• your skin has sebaceous glands that release acidic substances to kill pathogens
• your mouth contains lysozyme enzymes
• your nose has hairs and mucus to stop pathogens entering the body
• salmonella is a bacteria that causes vomiting, diarrhoea and a fever. You get it when food is prepared in unhygienic conditions but poultry can be vaccinated against it
• rose black spots are fungal black spots that develop on leaves restricting photosynthesis from water or wind transmission. they can be treated by removing infected leaves
• tobacco mosaic is a viral diseases that leaves discolouration on leaves and is spread by human contact
• gonorrhoea is a bacterial disease that produces thick yellow discharge and is spread sexually but can be treated by antibiotics
• malaria is a protist that is spread by mosquitoes and causes a fever
• measles is a viral diseases spread by droplets in the air and causes fever and rashes but can be prevented by vaccinations
• HIV is a viral disease that develops months or years after infection and attacks the human immune system so you have less white blood cells and die from other pathogens
• antigens are the proteins on the surface of pathogens that are recognised by white blood cells
• is a pathogen passes the non-specific defenses the body starts an immune response
• phagocytes engulf pathogens and enzymes in the cell break it down
• lymphocytes recognise antigens and detect they are foreign so produce specific antibodies that cause pathogens to stick together so it is easier for them to be engulfed
• some white blood cells produce antitoxins which counteract the toxins released. by pathogens
• vaccinations introduce a dead or weakened version of a pathogen into your body and stimulate an immune response
• vaccines stimulate white blood cells to produce antibodies against the body and because the vaccine is weakened the person has no symptoms
• if a person gets infected after being vaccinated the required lymphocytes are able to reproduce rapidly and destroy it
• drugs are identified and researched then preclinical trials take place and then clinical trials before it can be used
• drugs are substances that cause changes to the body
• drugs can be extracted from natural sources or synthesised by chemists
• aspirin is from willow bark