The Heart

• Heart


  A double pump organ
• Oxygenated blood flow


  1. Enters the left side of the heart

  2. Pumped to the rest of the body (the systemic circuit)
• Left ventricle


  • Has a thicker muscle wall than the right ventricle
  • Pumps blood at high pressure around the entire body
• Deoxygenated blood flow


  1. Enters the right side of the heart

  2. Pumped to the lungs (the pulmonary circuit)
• Right ventricle


  • Pumps blood at lower pressure to the lungs
• Septum


  • A muscle wall that separates the two sides of the heart
• Veins


  Blood is pumped towards the heart
• Arteries


  Blood is pumped away from the heart
• Coronary arteries


  Supply the cardiac muscle tissue of the heart with oxygenated blood
• Heart is a muscle


  Needs a constant supply of oxygen (and glucose) for aerobic respiration to release energy to allow continued muscle contraction
• Valves


  • Present to prevent blood flowing backwards
• • Red blood cells are specialised cells which carry oxygen to respiring cells
  • They are adapted for this function in 3 key ways
  • They are full of haemoglobin, a protein that binds to oxygen to form oxyhaemoglobin
  • They have no nucleus which allows more space for haemoglobin to be packed in
  • The shape of a red blood cell is described as being a 'biconcave disc'  this shape gives them a large surface area to volume ratio to maximise diffusion of oxygen in and out
• Away in arteries


  Refers to the direction of blood flow relative to the heart, with blood moving or being carried away from the heart and towards other parts of the body.
• Out of the heart


  Refers to the initial ejection of blood from the heart and into the circulatory system, with blood being expelled or ejected from the heart and into the aorta.
• Metabolism


  The chemical reactions that occur inside living cells
• Metabolic waste products produced by plants


  • Oxygen
  • Carbon dioxide
  • Water/water vapour
• Photosynthesis produces oxygen as a waste product in plants, not water vapour
• Light intensity


  Determines which gas accumulates as a waste product in plants
• At high light intensity more photosynthesis occurs so oxygen accumulates, while at low light intensity more respiration occurs so carbon dioxide accumulates
• During the day, with sufficient light for photosynthesis, oxygen is produced in excess and is the main waste product in plants
• Plants respire at night and during the day, the difference is that during the day photosynthesis occurs at a higher rate than respiration, so the waste products of photosynthesis accumulate
• The majority of water vapour that is lost in transpiration is not a metabolic waste product, but simply water drawn up from the roots by the transpiration stream