gcse biology chapter 4

• Valves


  Ensure that blood flows in the correct direction
• Circulatory system


  Double circulatory system
• Right ventricle


  Pumps blood to the lungs
• Gas exchange


  Occurs in the lungs
• Left ventricle


  Pumps blood around the rest of the body
• Faulty heart valves


  • May become faulty preventing it from opening fully or it might develop a leak
• Replacement for faulty heart valves

  Biological or mechanical valves
• Heart failure


  1. Donor heart, or heart and lungs can be transplanted

  2. Artificial hearts are occasionally used to keep patients alive whilst waiting for a heart transplant, or to allow the heart to rest as an aid to recovery
• Natural resting heart rate


  Controlled by a group of cells located in the right atrium that act as a pacemaker
• Artificial pacemakers


  Electrical devices used to correct irregularities in the heart rate
• Calculating bpm


  1. Count the amount of pulses you feel on your wrist or neck in 15 seconds

  2. Multiply by 4
• Blood flow in arteries

  From the heart
• Arteries


  • They have thick muscular walls and elastic fibres in the walls to withstand the pressure
• Blood flow in veins


  Towards the heart
• Veins


  • They have thinner walls, less muscular and elastic and valves to prevent back flow
• Capillary walls


  • One cell thick
• Thin capillary walls


  So diffusion of nutrients and glucose into and out of the blood is easy
• Stents


  Used to keep coronary arteries open if they narrow
• Blood


  A tissue connecting plasma in which red blood cells, white blood cells and platelets are suspended
• Red blood cells


  Contain haemoglobin
• Haemoglobin


  Binds to oxygen to transport it from the lungs to the tissues and cells, which need it for respiration
• White blood cells


  Help the body to fight infection
• Platelets


  Small fragments of cells that initiate the clotting process at wound sites
• Fatty material build up in coronary heart disease

  Layers of fatty material
• Fatty material build up


  Narrows the coronary arteries
• Narrowing of coronary arteries


  Reduces the flow of blood through them resulting in a lack of oxygen to the heart muscle
• Stents


  Used to keep coronary arteries open
• Statins


  Used to reduce blood cholestrol levels which slow down the rate of fatty material deposit
• Factors that increase the likelihood of getting CHD


  • Smoking
  • High salt intake
  • High (blood) cholesterol
  • High blood pressure / stress
  • Lack of exercise / obesity
  • Heredity / genes / familial
  • Gender
• Coronary artery


  Supplies blood to the heart
• Diet high in saturated fat


  Often leads to plaque forming
• Examples of cardiovascular diseases


  • Coronary heart disease
  • Faulty valves
  • Heart failure
• Cardiovascular diseases


  Affect the heart and blood vessels
• Coronary arteries


  Supply the cells of the heart with everything they need e.g. oxygen
• Muscle cells of the heart

  Use oxygen in respiration to produce energy required for muscle contraction
• Fatty build up


  Made from bad LDL cholesterol, narrowing the luminous of the vessel
• Blood vessel being narrow


  Restricts the flow of blood, limits the amount of oxygen reaching the cells and can ultimately cause a heart attack
• Stents


  Reduce the risk of patients with the disease having a heart attack and remain effective for a long time
• Statins


  Drugs that reduce the amount of 'bad' or LDL cholesterol in the blood, preventing fatty deposits forming and stopping vessels getting blocked
• Statins


  Reduce the risk of strokes, coronary heart disease and heart attacks and increase the levels of 'good' or HDL cholesterol in the blood