Organisation of animals

• Circulatory system


  The main transport system in humans, with blood vessels as a network of roads transporting blood, oxygen, nutrients, and waste
• Heart

  • Pumps blood around the body by contracting (squeezing)
  • Has four chambers with valves and blood vessels transporting things in and out of it
  • Key organ of the circulatory system
• Blood flow through the heart

  1. Blood enters right atrium from vena cava

  2. Blood enters left atrium from pulmonary vein

  3. Atria contract, pushing blood into ventricles

  4. Ventricles contract, pushing blood out of the heart - left ventricle to aorta, right ventricle to pulmonary artery
• Pulmonary circulation


  The right side of the heart pumps blood to the lungs for gas exchange
• Systemic circulation


  The left side of the heart pumps oxygenated blood to the rest of the body
• Arteries


  • Carry blood away from the heart
  • Have thick, elastic walls to withstand high pressure
  • Lumen (middle space) is narrow
• Capillaries


  • Tiny vessels where substances are exchanged
  • Have permeable walls to allow diffusion of substances
  • Only one cell thick
• Veins


  • Carry blood back to the heart
  • Have thin walls with large lumen
  • Have valves to prevent backflow
• Blood flow in humans is called a double circulation because the blood is pumped twice from the heart in a single circuit - to the lungs and then to the rest of the body
• Communicable diseases


  Diseases that can spread between organisms
• Non-communicable diseases


  Diseases that do not spread between people or animals
• Examples of non-communicable diseases include diabetes, cancer, and heart disease
• Coronary heart disease


  A disease of the coronary arteries that supply the heart with oxygen, caused by blockages from fatty deposits
• Stents


  • Tubes inserted into coronary arteries to force them to stay open and improve blood flow
  • Can have complications and risk of infection
• Statins


  • Drugs that reduce cholesterol levels in the blood to prevent fatty deposits
  • Can have dangerous side effects like liver damage
• Heart transplant


  • Replacement of the whole heart, using either donor hearts or artificial hearts
  • Risky surgery that can lead to infection
• Benign tumours


  • Non-cancerous growths that stay in one place and grow slowly
• Malignant tumours


  • Cancerous growths that can invade other tissues and spread (metastasize)
• Cell division is a normal process, but uncontrolled cell division can lead to the formation of tumours
• Risk factors are things that increase the likelihood of developing a disease
• Examples of risk factors

  • Obesity
  • Smoking
  • Poor diet
  • Lack of exercise
  • Stress
  • Environmental factors
• Obesity can lead to type 2 diabetes and cardiovascular disease
• Smoking causes lung and heart diseases, including lung cancer
• Obesity


  Being dangerously overweight can cause Type 2 diabetes and cardiovascular disease
• Obesity


  Leads to high blood pressure and the arteries get blocked by fatty deposits, which can cause cardiovascular disease
• Type 2 diabetes


  The body's cells respond less effectively to the hormone insulin and this disrupts how your body processes sugar
• Type 2 diabetes can be controlled by diet and exercise but there is no cure for it
• The risks of developing cardiovascular disease and Type 2 diabetes can be reduced by eating a balanced diet of whole foods, things that aren't processed, and exercising regularly
• Smoking


  Causes heart and lung diseases, things like lung cancer
• Gas exchange in the lungs

  1. Air travels down the trachea

  2. Trachea splits into bronchi

  3. Bronchi split into bronchioles

  4. Bronchioles end in alveoli

  5. Oxygen travels from alveoli into blood, carbon dioxide diffuses from blood into alveoli
• There is no safe level of smoking and that includes passive smoking, being around people that are smoking
• Excessive alcohol drinking


  The liver processes alcohol and each time it does, some of the liver cells die. Excessive drinking over many years can prevent regeneration, leading to serious and permanent damage to your liver. It can also lead to brain shrinkage, memory problems and psychiatric issues
• Smoking and drinking when pregnant is not a good idea, because it reduces the oxygen that the baby needs during development, and this can lead to a whole load of issues pre- and post-birth
• Causation


  Something makes another thing happen
• Correlation


  There's some kind of relationship, but it's not necessarily cause and effect
• Non-communicable diseases have human and financial costs
• Human costs


  The impacts that disease has on human beings, such as reduced life expectancy, quality of life and mental health
• Financial costs


  The costs to individuals, healthcare systems and society of treating non-communicable diseases
• Obesity


  Increases the chances of being diagnosed with bowel and liver cancer
• A poor diet often involves lots of processed foods - crisps, chocolate bars and sausage rolls - and not enough unprocessed foods, like fruits, vegetables, wholegrains and nuts