The heart

• The circulatory system carries food and oxygen to every cell in the body

  it also carries waste products to where then can be removed from the body
• The double circulatory system

  
• Double circulation

  
• Why is a double circulatory system beneficial?

  • oxygenated and deoxygenated blood are kept seperate
  • The increases the efficiency of oxygen transport and energy production in the body
  • High blood pressure can damage the delicate capillaries in the lungs. By having a double circulatory system, blood pressure can be lower when going the the lungs but higher when pumping blood to the rest of the body
  • This means that organisms with a double circulatory system can be more active since blood can reach their respiring tissues more quickly due to the higher pressure
• The structure of the heart

  
• The structure of the heart

  
• What type of blood returns to the heart via the vena cavae?

  Deoxygenated blood
• Where does deoxygenated blood flow after entering the heart?

  Into the right atrium
• What happens when both atria contract?

  Blood enters the right ventricle
• What occurs when both ventricles contract?

  Deoxygenated blood leaves the heart
• Through which artery does deoxygenated blood leave the heart?

  Pulmonary artery
• What happens to deoxygenated blood in the lungs?

  It releases carbon dioxide and picks up oxygen
• How does oxygenated blood return to the heart?

  Through the pulmonary veins
• Where does oxygenated blood enter the heart?

  Into the left atrium
• What happens when both atria contract after oxygenated blood enters?

  Oxygenated blood enters the left ventricle
• What occurs when both ventricles contract after oxygenated blood fills the left ventricle?

  Oxygenated blood leaves the heart through the aorta
• What is the complete pathway of blood flow through the heart and lungs?

  1. Deoxygenated blood returns via vena cavae
  2. Enters right atrium
  3. Both atria contract, blood enters right ventricle
  4. Both ventricles contract, blood leaves through pulmonary artery
  5. Blood enters lungs, releases CO2, picks up O2
  6. Oxygenated blood returns via pulmonary veins
  7. Enters left atrium
  8. Both atria contract, blood enters left ventricle
  9. Both ventricles contract, blood leaves through aorta
• The heart is made of muscle tissue and the muscle tissue on the left side of the heart is thicker than the right

  So that it can pump the blood at height pressure enabling the blood to reach all of the body
• The heart has 4 valves

  2 are between the stria and ventricles

  2 are between the ventricles and the vessels exiting the heart (aorta and pulmonary artery)
• The valves keep the blood flowing the correct direction- they prevent back flow of blood
• resting heart rate is controlled by a group of cells in the right atrium called pacemaker cells - they control the beating of the heart
• pacemaker cells

  1. The produce a small electric impulse which spreads to the surrounding heart muscle cells and causes them to contract
  2. The electric impulse travels through the muscle cells of the atria first and then the ventricles
  3. This causes the atria to contract before the ventricles
• The heart is made of muscle tissue - this enables it to contract and pump the blood

  The heart muscle tissue needs a supply of blood (and oxygen) so that it can work efficiently

  this is achieved by the coronary arteries - arteries which originate from the aorta and run along the outside surface of the heart supplying it with blood
• A circulatory system functionally connects the organ of exchange (lungs) with the body cells

  organisms require a circulatory system to supply cells with the things that they need, and to remove waste products of metabolism
• What does a cells need that the blood delivers to it?

  Oxygen, glucose and nutrients (minerals and vitamins)
• What is the main waste product of a cell that transports the blood away?

  Carbon dioxide
• Which structures make up the circulatory system in humans.

  a muscular pump: heart

  A circulatory fluid: blood

  A set of tubes: blood vessels

  A site of exchange: capillaries
• What different cells can be found in blood?

  1. Plasma
  2. Platelets
  3. Red blood cells
  4. White blood cells
• Blood vessels

  Arteries:

  Carry blood away from the heat

  They have thick muscular walls

  The blood in arteries is at a higher pressure

  They have an elastic layer in the wall to aid elastic recoil
• Blood vessels

  Veins:

  Carry blood back to the heart

  The contain valves to stop the back flow of blood

  The blood in veins is at a lower pressure so the walls don’t need to be as think

  The lumen is bid to help the blood flow despite the lower pressure
• Blood vessels

  Capillaries:

  The are really tiny - to small to see - and carry blood really close to every cell in the body to exchange substances with them

  Have extremely thin walls to allow nutrients and waste products to move in and out efficiently

  Thousands upon thousands of capillaries in our body’s
• Structure of blood vessels

  
• calculating the rate of blood flow

  
• Ventricles Contract

  When the ventricles contract, they squeeze together and pump blood out of the heart. This contraction is called ventricular systole.
• Ventricular Systole

  The contraction of the ventricles, resulting in the pumping of deoxygenated blood out of the heart.
• Deoxygenated Blood

  Blood that has already given up its oxygen to the body and is being pumped to the lungs to pick up more oxygen or to the rest of the body.
• Pulmonary Valves

  The valves that allow deoxygenated blood from the right ventricle to flow into the pulmonary artery and on to the lungs.