Circulatory System

• Blood


  Made up of red blood cells, white blood cells, platelets, and plasma
• Parts of blood


  • Red blood cells
  • White blood cells
  • Platelets
  • Plasma
• Red blood cells


  • Flattened, biconcave, disc shaped cells
  • Red in colour due to haemoglobin
  • No nucleus
• White blood cells


  • Bigger than red blood cells
  • Have a nucleus
  • Colourless
• If there is a shortage of iron

  • Person won't have enough red blood cells (anaemia)
  • Less oxygen will be carried around the body
• White blood cells


  • Defend the body against pathogens
  • Number increases rapidly during infection
• Platelets


  Clot the blood to prevent bleeding and blood loss
• Plasma


  • Liquid part of blood, 90% water
  • Carries dissolved substances around the body
• Substances carried in plasma


  • Small soluble food molecules
  • Waste chemicals
  • Hormones
  • Mineral salts
• Circulatory system


  Double circulatory system - blood passes through the heart twice
• Circulations


  • Pulmonary circulation - blood pumped from heart to lungs and back
  • Systemic circulation - blood pumped from heart to body and back
• Heart


  • Made of cardiac muscle
  • Coronary arteries supply oxygen and glucose to heart muscle
• If a blood clot blocks a coronary artery

  Heart muscles won't get enough oxygen and will stop working (heart attack)
• Parts of the heart

  • Pulmonary artery
  • Vena cava
  • Semi-lunar valves
  • Aorta
  • Pulmonary vein
  • Right atrium
  • Right atrio-ventricular valve
  • Right ventricle
  • Left atrium
  • Left atrio-ventricular valve
  • Left ventricle
• Flow of blood through the heart

  1. Vena cava carries blood to right atrium

  2. Blood passes through right atrio-ventricular valve to right ventricle

  3. Right ventricle pumps blood through semi-lunar valve to pulmonary artery

  4. Pulmonary artery carries blood to lungs

  5. Pulmonary vein carries oxygenated blood to left atrium

  6. Blood passes through left atrio-ventricular valve to left ventricle

  7. Left ventricle pumps blood through semi-lunar valve to aorta

  8. Aorta carries blood to body
• Facts about the heart

  • Heart is made of muscle that contracts to pump blood
  • Heart is divided into 2 halves
  • Blood flows in one direction through each half
  • Atrio-ventricular valves prevent backflow
  • Semi-lunar valves prevent backflow from arteries
  • Tendons attached to valves to prevent them being pushed inside out
  • Right side pumps blood to lungs
  • Left side pumps blood to body
  • Atria have thin walls, ventricles have thick walls
• Arteries


  • Have thick walls to carry blood under high pressure away from heart
• Veins

  • Have thin walls to carry blood under low pressure back to heart
• Capillaries

  • Smallest blood vessels that carry blood through organs
  • Walls are very thin to allow easy diffusion of substances
• Substances diffusing between capillaries and body cells

  • Oxygen and glucose
  • Carbon dioxide
• Cardiovascular disease (CVD)


  Diseases of the heart and circulatory system
• Types of CVD


  • Coronary heart disease
  • Heart attacks
  • Angina
  • Strokes
• Risk factors for CVD

  • High fat and salt diet
  • High blood pressure
  • High blood cholesterol
  • Smoking
  • Genetic factors
  • Lack of exercise
• Atherosclerosis

  Arteries become clogged with fatty plaques, restricting blood flow
• Effects of atheroma

  • Makes it more difficult for blood to flow through arteries
  • Increases likelihood of blood clots forming
  • Can block small arteries, leading to heart attack or stroke
• Treatments for CVD


  • Statins (drugs to control blood cholesterol)
  • Angioplasty (surgery to remove blockages)
  • Lifestyle changes (diet, exercise, stop smoking)
• Statins


  • Control blood cholesterol levels but may cause side effects
• Angioplasty


  • Improves blood flow in coronary vessels but can be a temporary remedy
• Lifestyle changes


  • Reduce risk of CVD but require high level of self-discipline and long-term commitment