Organisation B

• what are the four heart chambers?

  Right atrium, right ventricle, left atrium, left ventricle.
• what happens when the atria contracts?

  blood flows to the atria from the vena cava and the pulmonary vein, when the atria contracts it pushes blood to the ventricles.
• what are the walls of the heart made up of?

  muscle tissue
• what happens when the ventricles contract?

  forces blood into the pulmonary artery, aorta and out of the heart
• what does the right ventricle do?

  pumps deoxygenated blood to the lungs so it can take in oxygen then returns the blood to the heart
• what does the left ventricle do?

  pumps oxygenated blood around all the other organs
• which atrium is responsible for being the hearts pacemaker?

  the right atrium (has a group of cells) which produce a small electric impulses, then spreads to surround muscle cells, the muscles contract.
• what happens if your bodies natural pacemaker doesn't work? (irregular heartbeat)

  • you get an artificial pacemaker which is a little device implanted under the skin, it has a wire going to the heart. It produces electric current to keep the heart beating regularly
• what do the arteries do?

  carries blood away from the heart
• what does the capilleries do?

  connects the arteries and the veins
• what does the veins do?

  carries blood to the heart
• describe the structure of the arteries:

  • the heart pumps out blood at a high pressure so the arteries have thick, strong and elastic walls
  • has a small lumen
  • contains thick layers of muscle which makes them strong
  • has elastic fibres which allows them to stretch and spring back
• describe the structure of the capillaries:

  • the walls are one cell thick
  • has permeable walls so substances can diffuse in and out
  • supplies food and oxygen but takes out any waste such as CO2
• describe how veins are adapted to carry blood back to the heart:

  • low pressure so doesnt have thick walls
  • has a bigger lumen to help the blood flow
  • has valves to keep blood flowing in the right direction
• all arteries carry oxygenated blood except for the pulmonary artery
• all veins carry deoxygenated blood except for the pulmonary vein
• arteries to capillaries to veins
• what do red blood cells do?

  carrys oxygen from the lungs to cells in the body
• describe the sturcture of red blood cells?

  • diconcave disc shape which gives it a large surface area to volume ratio, faster oxygen diffusion
  • no nucleas so more room for oxygen
• what do red blood cells contain?

  a red pigment called haemoglobin which carries oxygen

  oxygen + haemoglobin = oxyhaemoglobin
• what do white blood cells do?

  defends against infection

  some produce antibodies
• describe the structure of white blood cells:

  they can change shape to gobble up unwelcome microorganisms

  it does infact have a nucleas
• what do platelets do?

  • helps to clot blood
  • stops blood from pouring out
  • stops microorganisms from getting in
• what happenes if you lack platelets?

  excessive bleeding and bruising
• describe the structure of platelets:

  no nucleas

  tiny fragments
• what does the plasma do?

  Transports nutrients, hormones, and waste products such as CO2
• what is an organ?

  • a group of different tissues working together on a common function
• what is a plant?

  • an organ
• what are part of the cardiovascular system?

  • heart
  • blood vessels
• what are the levels of organisation?

  • organelles
  • cells
  • tissue
  • organ
  • system
• why is the digestive system considered an organ system`?

  • as it is a group of different tissues working on a common function
  • digesting and absorbing food
  • the pancreas releases digestive enzymes which digest food molecules