blood, blood vessels,heart+circulation

• Main components of blood

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


  Carry oxygen from the lungs to the body's tissues
• Red blood cells


  • Don't have a nucleus, which means more space for hemoglobin and oxygen
  • Shaped like a biconcave disc, which gives them a large surface area for absorbing oxygen
• White blood cells


  Essential part of the immune system, defend against infection
• How white blood cells defend against pathogens

  • Phagocytosis (engulf/consume microorganisms)
  • Produce antibodies that bind to and help destroy pathogens
  • Produce antitoxins that neutralize toxins produced by pathogens
• White blood cells


  Have a nucleus, unlike red blood cells
• Platelets


  Small fragments of cells that float in the blood and help stop bleeding by clotting
• Plasma


  Pale straw-colored liquid that makes up over half the blood's volume, carries nutrients, waste, hormones, antibodies, and other substances
• Most adults have about 5 liters of blood flowing through their circulatory system at any one time
• Artificial blood


  Blood substitute consisting of salt water, adds volume to the circulatory system but doesn't contain red blood cells so can only replace about 1/3 of the blood
• Blood transfusion


  Giving a person real blood donated by blood donors, contains red blood cells which is key for surviving blood loss
• Plasma is the liquid component of blood that carries various substances such as hormones, nutrients, and waste products.
• Platelets are small cell fragments that help in blood clotting and wound healing.
• The heart acts as the pump for the circulatory system
• Blood vessels


  1. Arteries carry blood away from the heart

  2. Capillaries exchange nutrients and oxygen with tissues

  3. Veins carry blood back to the heart
• Arteries


  • Carry blood directly from the heart
  • Blood inside is at high pressure
  • Have thick walls with muscle and elastic tissue to withstand high pressure
• Capillaries


  • Very small vessels
  • Come into close contact with cells
  • Walls are single cell thick and permeable
  • Total cross-sectional area is much larger than arteries, so blood flows more slowly
• Veins


  • Relatively large vessels
  • Have the biggest lumen of any blood vessels
  • Walls are thin with little muscle and elastic tissue
  • Have valves to prevent backflow of blood
• Calculating rate of blood flow

  Divide volume of blood by time taken
• 2500 ml of blood passes through the aorta in 8 minutes
• Circulatory system


  An example of an organ system whose role is to transport oxygen and nutrients to the body's tissues
• Circulatory system


  • Relies on 3 main things: blood, blood vessels, heart
• Blood


  Carries oxygen and nutrients
• Blood vessels


  Hold the blood
• Heart


  Pumps the blood to keep it moving through the vessels
• The circulatory system can be thought of as a double circulatory system
• Path of blood through the heart

  1. Flows into right atrium and left atrium

  2. Flows from atria into ventricles

  3. Flows out of ventricles into pulmonary artery and aorta

  4. Cycle repeats around 70 times per minute
• Atria


  Top chambers of the heart
• Ventricles


  Bottom chambers of the heart
• Valves


  Prevent blood from flowing backwards, ensure blood flows in the right direction
• Vena cava


  Carries deoxygenated blood to the heart
• Pulmonary vein


  Carries oxygenated blood to the heart
• Pulmonary artery


  Carries deoxygenated blood from the heart to the lungs
• Aorta


  Carries oxygenated blood from the heart to the rest of the body
• Pacemaker cells


  Produce electrical impulses to regulate the heart's contractions
• Artificial pacemaker


  A device implanted to regulate the heart's contractions when pacemaker cells don't work properly
• Arteries carry blood away from the heart, veins carry blood to the heart
• The heart needs its own supply of oxygenated blood, which it gets from coronary arteries
• where is the protein haemoglobin found in a red blood cell 


  cytoplasm
• what kind of nucleus do phagocytes have

  lobed nucleus