Topic 2 Keeping Healthy

• Pathogens


  Agents which cause infectious disease, usually live microorganisms such as bacteria and viruses
• Diseases


  • Can reduce both mental and physical health by infecting and damaging tissues and organs within the body
  • Can destroy cells, produce toxins and inhibit cells from carrying out their usual function, harming the infected organism
  • Often cause symptoms, although not all diseases have visible symptoms and many symptoms do not appear immediately due to an incubation period
• Communicable diseases


  Caused by infection from a virus, bacteria, fungi or protist, can be passed between organisms and spread throughout a population
• Non-communicable diseases


  Usually associated with genetic, environmental and lifestyle factors, cannot be spread directly between different organisms
• Mechanical barriers


  Defences against infection in the human body, including hairs in the nose and skin
• Chemical barriers


  Defences against infection in the human body, including mucus, stomach acid and tears
• Bacterial barriers


  Defences against infection in the human body, where bacteria (e.g. in the gut) helps to kill foreign pathogens
• Platelets


  • Cell fragments found in the blood that promote blood clotting, adapted to be very small and lack a nucleus to be flexible and move easily through narrow capillaries
  • Release chemicals to begin a chain reaction to form a mesh over a cut in a blood vessel and change shape to become sticky to seal the cut
• White blood cells


  Detect the difference between self and non-self by using receptors on their cell surface to identify antigens on pathogens, can engulf and digest pathogens or release chemicals to trigger antibody release
• Antibodies


  1. shaped proteins released once a pathogen has been identified, travel to the site of the pathogen through the blood and bind to the antigens on the surface to neutralise it, clump foreign cells together to make them too big to enter and destroy cells
• Plant defences


  • Physical barriers like cell wall and waxy cuticle that make it hard for pathogens to enter
  • Antimicrobial substances like those found in garlic and ginger that prevent pathogens
• Preventing plant disease


  1. Regulating movement of infected plants

  2. Sourcing healthy plants and seeds

  3. Destroying infected plants

  4. Polyculture - growing many crop varieties in the same space

  5. Crop rotation - changing the crop grown each year

  6. Chemical and biological control
• Preventing human and animal disease

  1. Contraception to reduce spread of STDs

  2. Sterilising wounds

  3. Hygiene and sanitation to prevent diseases spread through food and water

  4. Restricting travel

  5. Destruction of infected animals

  6. Vaccination to stimulate antibody and memory cell production
• Aseptic techniques


  Procedures used when handling samples and carrying out identification tests to avoid contamination and prevent the spread of pathogens, including wiping down surfaces, sterilising equipment, and washing hands
• Monoclonal antibodies


  Identical antibody clones made from one parent cell, can be cultured in a laboratory and used in diagnostic tests to detect the presence of specific molecules like hormones
• Monoclonal antibodies can be used to diagnose HIV, AIDS, cancer and many other diseases
• Handling a sample


  1. Open for a minimum amount of time

  2. Close windows and doors to limit air currents

  3. No eating or drinking near the sample

  4. Wash hands before handling the sample
• Monoclonal antibodies


  Identical antibody clones made from one parent cell
• Monoclonal antibodies


  • Can be cultured in a laboratory
  • Used in diagnostic tests, such as pregnancy tests
• Pregnancy test using monoclonal antibodies

  1. Detect the presence of HCG, a hormone only produced during pregnancy

  2. HCG binds to the monoclonal antibodies and results in a colour change, indicating pregnancy
• Monoclonal antibodies


  • Specific - the type used in pregnancy tests will only bind to HCG
• Other tests using monoclonal antibodies

  • Diagnose HIV, AIDS and cancer, amongst many other diseases
• Tests using monoclonal antibodies


  • Much easier and faster to carry out
  • Give more accurate results
  • Patients can be treated faster and more accurately
• Producing monoclonal antibodies


  1. Inject a specific antigen into an animal, such as a mouse

  2. Animal has an immune reaction and antibody-producing cells are taken

  3. Cells are fused with tumour cells to make hybridoma cells

  4. Hybridoma cells divide to produce more monoclonal antibodies

  5. Cells producing the correct antibody are selected and cultured
• Non-communicable diseases


  Diseases that can develop due to a range of both lifestyle and genetic factors
• Risk factors


  Factors that may increase the risk of one or many diseases, but do not directly cause them
• Risk factors


  • Unhealthy diet
  • Lack of exercise
  • Age
  • Inherited risks
  • Environmental risk factors
  • Drugs and smoking
• Unhealthy diet


  • Eating a high amount of saturated fat can cause high blood pressure and lead to fatty deposits in arteries, increasing the risk of cardiovascular disease
  • A high sugar diet can lead to type-2 diabetes
• Lack of exercise


  • An inactive lifestyle can lead to obesity, which increases the risk of cardiovascular disease, cancer and diabetes
  • People who exercise regularly have a lower pulse and recovery rate which puts less strain on the heart and blood vessels
• Age


  Generally, as age increases so does the risk of developing diseases, but some diseases are more common in lower age groups
• Inherited risks


  Some diseases, such as heart and circulatory diseases, can run in families and are passed on in the DNA
• Environmental risk factors


  Some environmental factors can increase the risk of certain diseases, e.g. UV radiation can increase the risk of skin cancer by causing DNA mutations
• Drugs and smoking


  • Smoking increases the risk of lung cancer and coronary heart disease, among many other diseases
  • It damages the lining of blood vessels, reduces the amount of oxygen in the blood, raises blood pressure and increases the likeliness of blood clots which lead to heart attacks and strokes
  • Other drugs including alcohol can increase the risk of heart disease, cancers and liver diseases
• Autoimmune diseases such as lupus


  Weaken the immune system, making it more likely for other diseases to infect the body
• Viruses


  Can be a trigger for cancers, and HIV targets cells in the immune system, leading to AIDS and increasing the risk of tuberculosis and tumours
• Sickle cell anaemia


  Prevents malaria by distorting the shape of red blood cells
• Medicines


  Can work by curing a disease, reducing the symptoms, or by decreasing the length of sickness
• Painkillers


  Reduce the symptoms of a disease by blocking pain receptors
• Antibiotics and antiviral drugs

  Work to cure the patient by killing the pathogen or inhibiting its growth
• Antibiotics


  • Used to treat bacterial infections
  • Some kill bacteria by destroying their cell wall, leading to the cell bursting
  • Others inhibit the growth of the bacteria