TOPIC 3 INFECTION AND RESPONSE

• what is bacteria


  Bacteria are one-celled living organisms
• how do bacteria make u feel ill

  divide rapidly by binary fission

  kill cells and produce harmful toxins
• how do viruses cause disease

  invade and reproduce inside living body cells, leading to cell damage
• what are pathogens


  microorganisms that cause disease
• how can pathogens be spread

  water air direct contact
• define health


  A state of complete physical, mental, and social well-being
• what is tmv


  tobacco mosaic virus

  affects plants

  spread by contact

  causes a mosaic pattern on leaves,leaves become discoloured cant carry photosynthesis
• what is hiv


  spreads by sexual contact or exchange of body fluids

  flu like symptoms
• what are aids


  aids occur at the late stage of the hiv infection, when the bodys immune system and cope with other infections
• why cant a plant carry out photosynthesis if infected with tmv

  cause discoloration on the leaves, reducing the amount of pigment in the leaves
• what are measles


  virus

  spread by droplets from an infected persons sneeze or cough

  fever, high temperature, rash
• what is salmonella


  A type of bacteria that causes food poisoning

  symptoms diarhhoea

  vomitting

  limited by keeping raw meat away from cooked meat
• what is gonorhea?


  std

  passed on by unprotected sex

  symptoms: thick, yellow green discharge from vagina or penis

  use a condom or antbiotics
• what is rose black spot

  A fungal disease where purple or black spots develop on leaves, which often turn yellow and drop early.

  spread by water and wind

  treated using fungicides
• what is malaria


  Malaria is a disease caused by protist pathogens.

  spread by mosquitos

  symptons: fever shaking

  controlled by preventing mosquitos
• how does the skin defend the body

  the skin provides a physical barrier to pathogens and may also produce antimicrobial substances to kill pathogens
• what does the nose and trachea and bronchi do

  nose has hairs and mucus which trap pathogens

  trachea and bronchi have mucus that transport pathogens
• What does the stomach do?

  secretes hydrocholric acid, kills any pathogens present
• how does phagocytosis protect us

  white blood cells ingest and destroy pathogens so they cannot infect more cells
• How does antibody production protect us against disease?

  each pathogen has an antigen

  once antibdoies bind the pathogens clump together making it easier for white blood cells to find them
• how does antitoxins help

  antitoxins bind to toxins released by pathogens and neutralise them
• what is vaccinaiton


  involves making an individual immune to a certain disease
• what are antigens


  substances that our immune system defects as foreign
• What are antibodies produced by?

  B-lymphocytes - a type of white blood cell
• why dont antibiotics destroy viruses

  Viruses reproduce using your own body cells, which makes it very difficult to develop drugs that destroy just the virus without killing the body's cells
• what are painkillers


  Drugs that relieve the pain and help reduce the symptoms of a disease

  they dont kill pathogens they help reduce symptoms
• what are communicable diseases


  can be passed on
• how does the body produce antibodies

  when white blood cells come across a foreign antigen they produce proteins called antibodies

  antibodies lock onto the invading cells so they can be found and destroyed by other white blood cell
• what is cancer


  uncontrolled cell growth
• benign tumor is


  An abnormal tumors which are contained in one area

  usually within a membrane

  isnt dangerous

  isnt cancerou
• what is a maligant tumor

  tumor grows and spreads to neighbouring healthy tissues

  cancerous

  invade healthy tissu
• what is herd immunity


  the resistance to the spread of a contagious disease within a population that results if a sufficiently high proportion of individuals are immune to the disease, especially through vaccination.
• How do vaccines work?

  involve injecting small amounts of dead or inactive pathogens

  these pathogens carry antigens

  body produces alot of antibodies

  creates memory cells

  if the pathogen enters again the immune system recognizes it and prodcues antibodies quickly
• steps of testing drugs

  preclinical testing: using cells, tissues and live animals

  clinical testing:volunteers and patients

  placebo