Science Biology

• Health


  When you are well and maintaining your body well, the maintaining of the internal environment of our body
• Disease


  The body functions working differently then normal
• Homeostasis


  When the body prevents the external environment from changing the internal environment
• If homeostasis is not maintained in the internal environment, cells may not get everything they need or toxic wastes may accumulate in cells, eventually leading to diseases
• Keeping The Body In Balance

  1. When you get too hot, you sweat

  2. When you get too cold, you shiver
• Shiver


  Muscles contract and relax, helping you warm up
• Sweat


  Water evaporates, and the skin surface cools down
• The cells that make up our bodies function best in certain conditions. The body's ability to maintain a stable state despite these changes is called homeostasis
• The body needs to also keep its levels of sugar, salt and water. A key role is played by hormones
• Blood Glucose Levels


  1. If there is too much glucose, a hormone instructs target cells in the liver and muscles, called insulin, produced by the pancreas

  2. If the body cannot use insulin effectively, it causes a health condition called diabetes

  3. If the level of blood glucose gets too low, the pancreas releases a different hormone called glucagon. This hormone instructs cells to release glucose into the blood
• Type 1 Diabetes


  Pancreas cannot produce enough insulin to control blood glucose levels. People may need regular injections of insulin to help meet needs
• Type 2 Diabetes


  The target cells of insulin stop responding properly. It's also called insulin resistance, and it can often be treated by a change of diet
• Feedback Loops


  1. When a hormone is sent out into the body, the information is received and therefore affects other responses in the body

  2. The rate of hormone production and secretion is often regulated using negative feedback loops

  3. If a stimulus is received indicating that a hormone effect is happening too much, the response would be to produce less of that hormone. This is a change in a system that causes another change that brings it back to the starting position, and it is used to maintain homeostasis
• Infectious disease


  A disease caused by a pathogen which can be transmitted between people
• Pathogens


  • Bacteria
  • Viruses
  • Fungi
  • Protozoa
  • Microparasites
  • Prion
• Bacteria


  Prokaryotic (no membrane bound organelles)
• Viruses


  Non-living (acellular)
• Fungi


  Eukaryotic (have membrane-bound organelles)
• Healthy


  In a good physical or mental condition, in good health
• Bacteria


  Can quickly replicate in our bodies, killing cells. It can also produce toxins which can kill cells and cause an outsized, damaging immune reaction
• Virus


  Can get into someone's body, and produce clones of itself, overtaking other cells and infecting the body
• Fungi


  Specific fungi can reproduce 'spores' particles that can enter our body through the lungs or skin. It can spread quickly and damage many organs. Other fungal infections can be caused by an overgrowth of commensal fungus
• Bacteria


  Single celled organisms without a nucleus, usually around 0.2µm in diameter. Diseases can include strep throat, staph infections, tuberculosis, food poisoning, tetanus, pneumonia, syphilis
• Virus


  Non living particles that reproduce by taking over other cells, usually around 20-200nm. Diseases include common cold, flu, genital herpes, cold sores, measles, AIDs, chicken pox
• Fungi


  Simple organisms that grow as single cells or thread like filaments, usually 2-10µm in diameter. Diseases include ringworm, athlete's foot, tineas, candidiasis, histoplasmosis, mushroom poisoning
• Protozoa


  Single celled organisms with a nucleus, usually less than 50µm. Diseases can include Maralea, 'traveller's diarrhoea', giardiasis, trypanosomiasis, sleeping sickness
• Microparasites


  Multicellular organisms that do not multiply within the final host, usually can be seen with the naked eye. Diseases include nematodes, tapeworms, ticks, flukes, fleas
• Prion


  Abnormal pathogenic agents and they are transmittable, usually around 30.35kDa. Diseases include Creutzfeldt-Jakob disease (CJD)
• Contagious


  When an infectious disease can pass from one person to another
• Not all infectious diseases are contagious, a medical condition that cannot be spread from person to person is non-contagious. For a disease to be infectious, it needs to be caused by a pathogen
• Transmission methods


  • Eating contaminated food or drinking contaminated water
  • Breathing in infected saliva droplets after someone coughs or sneezes
  • Exchanging bodily fluids, such as blood or saliva
  • By a vector, such as a mosquito or tick
• Deadliness or virulence of a disease


  The percentage of infected people that die from it
• Contagiousness of a disease


  How easily it spreads
• Ways to prevent the spread of disease

  • Frequently wash your hands with soap
  • Avoid touching nose, eyes or mouth
  • Do not share cutlery with other people
  • Quarantine yourself if you are feeling unwell
• Epidemiologist


  A person who studies the branch of medicine which deals with the incidence, distribution and possible control of diseases
• Epidemic


  A more widespread outbreak that may affect the entire nation
• Pandemic


  An epidemic that is affecting the entire world
• Endemic


  An outbreak confined to a particular geographical area
• Direct transmission


  Occurs when there is physical contact between the infected person and the other person (skin-to-skin, herpes type 1)
• Indirect contact


  Occurs when there is no direct skin-to-skin contact (food-borne, salmonella)